Service life

The life of the motor is made with the deterioration of insulation or the consumption of sliding parts, the deterioration of bearings, etc

Life chart – Motor housing temperature

various factors, such as dysfunction, are mostly subject to bearing conditions. The life of bearings is described below, there are two kinds of body life and lubricant life.

The life of the bearing

1, lubricant due to thermal deterioration of the lubricant life

2, operating fatigue caused by mechanical life

In most cases, heat affects the life of the lubricant more than the weight of the load added to the bearings. Therefore, the lubricant life is estimated to the life of the motor, the biggest impact on the life of the lubricant is due to temperature, temperature greatly affected the life time.

How to start

Motor start-up methods include: full pressure direct start, self-coupled decompression start,y-δ start, soft starter, inverter.

Full pressure direct start:

Where both the capacity and load of the grid allow full pressure to start directly, it may be considered to use full voltage direct start. The advantages are easy to control, simple to maintain, and more economical. Mainly used for the starting of small-power motors, from the point of view of energy conservation, larger than 11kW motors should not use this method.

Self-coupled Decompression Start:

Using the multi-tap decompression of self-coupled transformers can not only meet the needs of different load starting, but also get a greater starting torque, which is often used to start a larger capacity motor decompression starting mode. Its greatest advantage is that the starting torque is large, which can reach 64% at direct start when its winding tap is at 80%. The starting torque can also be adjusted by taps. It is still widely used today.

y-δ Start:

For the normal operation of the stalactical winding for the triangular asynchronous motor, if the stalactical winding is connected into a star at start-up, waiting for the start-up to be completed and then connected into a triangle, you can reduce the starting current, reduce its impact on the power grid. Such a starting method is called a star triangle decompression start, or simply a star triangle start(y-δ start). When starting with a star triangle, the starting current is only 1/3of when the direct start is done by the triangle connectionmethod. If the starting current at direct start-up is measured from 6to7ie, the starting current is only 2to2.3 times when the star triangle is started.   This means that when starting with a star triangle, the starting torque is also reduced to 1/3of when the direct start is started by the triangle joinmethod. Suitable for use in cases where there is no load or light load starting. And compared with any other decompression starter, its structure is the simplest and cheapest. In addition, the star triangle start-up method also has the advantage of allowing the motor to operate under the star-shaped connection method when the load is light. At this point, the rated torque can be matched with the load, which can improve the efficiency of the motor, and thus save power consumption.

Soft starter:

This is the use of the transfer phase control principle of the silicon to achieve the motor pressure start, mainly used for the motor start control, starting effect is good but the cost is higher. Because of the use of SCR elements, the harmonic interference of SCR is large, which has a certain impact on the power grid. In addition, fluctuations in the power grid can affect the conduction of SCR components, especially if there are multiple SCR devices in the same grid. As a result, the failure rate of SCR components is higher, because of the power electronics technology involved, so the maintenance technician requirements are higher.

Drives:

The inverter is the motor control device with the highest technical content, the most complete control function and the best control effect in the field of modern motor control, which adjusts the speed and torque of the motor by changing the frequency of the power grid. Because of the power electronics technology, microcomputer technology, so high cost, maintenance technicians are also high requirements, so mainly used in the need to speed control and speed control requirements of high areas.

Speed adjustment method

Motor speed control methods are many, can adapt to the requirements of different production machinery speed changes. The output power of an electric motor changes with the speed when it is normally adjusted. From the point of view of energy consumption, the speed adjustment can be roughly divided into two  kinds:

(1) Keep the input power unchanged. By changing the energy consumption of the speed control device, the output power is adjusted to adjust the speed of the motor.

2 Control the input power of the motor to adjust the speed of the motor. Motors, motors, brake motors, variable frequency   motors, speed control motors, three-phase asynchronous motors,  high-voltage motors, multi-speed motors, two-speed motors and explosion-proof motors.

Structural classification

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Basic structure

The structure of a three-phase asynchronous motor consists of stalects, rotors and other accessories.

(i) The tyration (static part)

1, the tyration iron heart

Action: Part of the motor magnetic circuit on which a set of coyoclies are placed.

Construction: Stator iron heart is generally made of 0.35 to 0.5 mm thick surface with insulation of silicon steel sheet punching, stacking pressure, in the inner circle of the iron center has a uniform distribution of grooves, used to nest stator windings.

There are several types of synth iron heart grooves:

Semi-closed grooves: The efficiency and power factor of the motor are high, but winding lines and insulation are difficult. Generally used in small low voltage motors.

Semi-open grooves: Can be embedded molding windings, generally used in large, medium low voltage motors. The so-called molded windings, i.e. windings can be insulated before being put into the groove.

Open slot: for embedding molding windings, insulation method is convenient, mainly used in high-voltage motors.

2, the tyration winding

Function: is the circuit part of the motor, into the three-phase ALTER, to produce a rotating magnetic field.

Construction: By three in the space separated by 120 degrees of electricity angle, symmetrical arrangement of the structure is identical windings connected, these windings of the various coils according to a certain law embedded  in the styrust grooves.

The main insulation items of stator windings are as follows: (to ensure reliable insulation between the conductive parts of the windings and the iron heart, and reliable insulation between the windings themselves).

(1) Ground insulation: the insulation between the tator winding and the python’s iron heart.

(2) Inter-phase insulation: insulation between the stator windings.

(3) Insulation between the coils: Insulation between the wires of each phase stator winding.

Wiring in the motor junction box:

The motor terminal box has a terminal board, three-phase winding six head row up and down two rows, and the upper row of three terminal piles from left to right number 1(U1),2(V1),3(W1),the lower three terminal piles from left to right number 6(W2),4(U2). ),5(V2)to connect thethree-phase winding into a star or triangle join. All manufacturing and repair should be in this order.

3, the seat

Function: Fix the syringe iron heart and front and rear end covers to support the rotor, and play a protective, cooling and other roles.

Construction: the base is usually cast iron parts, large asynchronous motor seat is generally soldered with steel plate, micro-motor seat using cast aluminum. The seat of the closed motor has heat dissipation ribs to increase the cooling area, and the ends of the protective motor are covered with vents, so that the air inside and outside the motor can be directly convected to facilitate heat dissipation.

(ii) Rotor (rotating part)

1, three-phase asynchronous motor rotor iron heart:

Function: As part of the motor magnetic circuit and in the iron core groove to place rotor windings.

Construction: The material used, like the syringe, is punched and stacked by a 0.5 mm thick silicon steel sheet, and the outer circle of the silicon steel sheet is flushed with evenly distributed holes to place the rotor windings. Usually with the systation iron heart rushed backward silicon steel sheet inner circle to punch the rotor iron heart. Generally small asynchronous motor rotor iron heart directly pressed on the shaft, large and medium-sized asynchronous motor (rotor diameter of 300 to 400 mm or more) rotor iron heart with the help of the rotor support pressed on the shaft.

2, three-phase asynchronous motor rotor winding

Function: Cutting the serum rotating magnetic field produces induction of electric potential and current, and the formation of electromagnetic torque to make the motor rotate.

Construction: It is divided into rat cage rotor and winding rotor.

(1) Rat cage rotor: The rotor winding consists of multiple guides inserted into the rotor groove and two end rings in the loop. If the rotor iron heart is removed, the outer shape of the entire winding is like a rat cage, so called a cage winding. Small cage motors are made of cast aluminum rotor windings and are welded with copper bars and copper end rings for motors over 100KW.

(2) Winding rotor: winding rotor winding and stalect windings are similar, but also a symmetrical three-phase winding, generally connected to a star, three out-of-line head to the shaft of the three assembly rings, and then connected with the external circuit through the brush.

Features: The structure is more complex, so the application of winding motor is not as extensive as rat cage motor.  However, through the assembly ring and brush in the rotor winding circuit string additional resistance and other components, to improve the starting, braking performance and speed control performance of asynchronous motors, so in a certain range of requirements for smooth speed control equipment, such as cranes, elevators, air compressors and so on on the above.

(iii) Other accessories of a three-phase asynchronous motor

1, end cover: supporting role.

2, bearings: connecting the rotating part and the immobile part.

3, bearing end cover: protection bearings.

4, fan: cooling motor.  ^[1]

motor

Second, DC motor using octagonal full stacking structure, string winding, suitable for the need for positive and inverted automatic control technology. Depending on the user’s needs, it is also possible to make a stringed winding. The motor with center height of 100to280mm has no compensation winding, but the motor with center height of 250mmand280mm can be made with compensation winding according to specific conditions and needs, and the motor with center height of 315to450mm has compensation winding. The center height of 500to710mm motor form factor and technical requirements are in line with IEC international standards, the mechanical dimensions of the motor tolerances in line with ISO international standards.

Cooling mode

1) Cooling: When the motor is converting energy, a small part of the loss is always converted into heat, which must be continuously emitted through the motor housing and surrounding media, a process that we call cooling.

2) Cooling medium: a gas or liquid medium that transmits heat.

3) Primary cooling medium: a gas or liquid medium that is cooler than a component of the motor, which comes into contact with that part of the motor and takes away the heat it emits.

4) Secondary cooling medium: a gas or liquid medium with a temperature lower than that of the primary cooling medium, which is carried away by the heat emitted by the primary cooling medium through the outer surface of the motor or cooler.

5) Final cooling medium: Heat is transferred to the final cooling medium.

6) Peripheral cooling media: gas or liquid media in the surrounding environment of the motor.

7) Far-away medium: A medium far from the motor that draws motor heat through an inlet, outlet tube or channel and discharges the cooling medium to a distance.

8) Cooler: A device that transfers heat from one cooling medium to another and keeps the two cooling media separate.

Method code

1, the motor cooling method code is mainly composed of the cooling method logo (IC),the cooling medium circuitarrangement code, the cooling media code and the cooling medium movement of the driving method code.

The IC-loop layout code is the cooling media code and the push method code

2. The cooling method logo code is anacronym for InternationalCooling,expressed in IC.

3, cooling media circuit layout code with characteristic numbers, our company mainly uses 0,4,6,8 andso on, the following respectively said their meaning.

4, cooling media code has the following provisions:

If the cooling medium is air, the letter A describing the cooling medium can be omitted, and the cooling medium we use is basically air.

5, cooling media movement of the driving method, mainly introduced four.

6, cooling method code marking has simplified marking method and complete marking method, we should give priority to the use of simplified marking method, simplified marking method features, if the cooling medium is air, it means that the cooling media code A,in the simplified mark can be omitted, if the cooling medium is water, push mode 7,in the simplified mark, the number 7 can be omitted.

7, the more commonly used cooling methods are IC01,IC06,IC411,IC416,IC611,IC81W and so on.

Example: IC411 the full marking method is IC4A1A1

“IC” is the cooling mode logo code;

“4″ is a code name for the cooling media circuit (shell surface cooling).

“A” is the cooling media code (air).

The first “1″ is the primary cooling medium push method code (self-cycle).

The second “1″ is the secondary cooling media push method code (self-cycle).

IC06:bring your own blower external ventilation;

ICl7:cooling air inlet for pipes, outlet for blinds exhaust;

IC37:That is, the cooling air import and export are pipes;

IC611:Fully enclosed with air / air cooler;

ICW37A86:Fully enclosed with air/water cooler.

And there are a variety of derived forms, such as self-ventilation type, with axial wind model, closed type, air / air cooler type.

Motor classification

AC motor

Asynchronous motors

Asynchronous motors

Y-Series (low pressure, high pressure, variable frequency, electromagnetic braking).

JSJ series (low pressure, high pressure, variable frequency, electromagnetic braking).

Synchronized motor

TD series

TDMK series

DC motor

Normal DC motor

Normal DC motor

Z2 Series

Z4 Series

Dedicated DC motor

ZTP rail motor

ZSN cement swing kiln

The use and control of electric motor is very convenient, with self-starting,  acceleration,  braking, reversal, parking and other capabilities, can meet a variety of operating requirements; Because of its series of advantages, so in industrial and agricultural production, transportation, national defense, commercial and household appliances, medical equipment and other aspects of widespread use.

Product classification

1．  By working power supply

Depending on the operating power supply of the motor, it can be divided into DC motor and AC motor. The AC motor is also divided into a single-phase motor and a three-phase motor.

2．  By structure and how it works

Motors can be divided into DC motors, asynchronous motors and synchronous motors according to their structure and working principle. Synchronous motors can also be divided into permanent magnetic sync motors, magnetic resistance sync motors and magneto-stagnant ton cloth motors. Asynchronous motors can be divided into induction motors and AC converter motors. Induction motors are divided into three-phase asynchronous motors.

Asynchronous motors and cover extremely asynchronous motors, etc. AC converter motor is divided into single-phase serial motor,  AC DC two electric motivation and push motor.

3．  Sort by start and run

Motors can be divided into capacitive start-up single-phase asynchronous motors, capacitive running single-phase asynchronous motors, capacitive start-up operating single-phase asynchronous motors and phase-splitting single-phase asynchronous motors.

4．  By purpose

Motors can be divided into driving electric motors and controlling electric motors by use. Drive electric motor is also divided into power tools (including drilling, polishing, polishing, slotting, cutting, widening tools, etc.) electrical motivation, home appliances (including washing machines, electric fans,   refrigerators, air conditioners, recorders, video recorders, DVD players, vacuum cleaners, cameras, hair dryers, electric razors,   etc.) electric motivation and other general-purpose small machinery (including a variety of small machine tools, small machinery, medical equipment, electronic equipment, etc.) electric motivation. The control of electric motors is divided into stepper motors and servo motors.

5．  By structure of the rotor

The structure of the motor by rotor can be divided into cage-type induction motor (old standard called rat cage-type asynchronous motor) and winding rotor induction motor (old standard is called winding asynchronous motor).

6．  By speed of operation

Motors can be divided into high-speed motors, low-speed motors, constant-speed motors, speed-controlled motors according to the operating speed.

7． Classified by protective type

Open (e.g. IP11,IP22):The motor has no special protection forthe rotating and live parts except for the necessary support structures.

Closed (e.g. IP44,IP54):The rotating and charged parts inside the motor housing are subject to necessary mechanical protection to prevent accidental contact, but do not significantly interfere with ventilation. The protective motor is divided into: according to its ventilation protection structure

Mesh type: the vents of the motor are covered with perforated coverings, so that the rotating part of the motor and the live part cannot come into contact with the foreign object.

Drip-proof: The structure of the motor vent prevents vertically falling liquids or solids from entering the motor directly.

Splash-proof: The structure of the motor vent prevents liquids or solids from entering the motor in any direction directly at a 100-degree angle.

Closed: The structure of the motor shell prevents the free exchange of air inside and outside the enclosure, but does not require a complete seal.

Waterproof: The structure of the motor housing prevents water with a certain pressure from entering the motor.

Watertight: When the motor is immersed in water, the structure of the motor shell prevents water from entering the motor.

Submersible: The motor can operate in water for a long time under rated water pressure.

Explosion-proof: The structure of the motor housing is sufficient to prevent the gas explosion inside the motor from being transmitted to the outside of the motor, and causes the explosion of combustion gas outside the motor.

Example:IP44 indicates that the motor can protect against solid foreign bodies larger than 1mm from water splashing.

The meaning of the first digit after IP

0 No protection, no special protection.

1 Prevents solid foreign bodies larger than 50mm in diameter from entering the case, prevents large areas of the human body(e.g. hands) from accidentally touching live or moving parts of the shell, but does not prevent conscious access to these parts.

2 Prevents solid foreign bodies larger than 12mm in diameter from entering the case and prevents fingers from touching the live or moving part of the shell.

3 Prevents solid foreign bodies larger than 2.5mm in diameter from entering the case and prevents tools, metals, etc. with a thickness (or diameter) greater than 2.5 from touching the live or moving part of the shell.

4 Prevents solid foreign bodies larger than 1mm in diameter from entering the case and prevents tools (or diameters) larger than 1mm from touching live or moving parts of the shell.

5 Prevents dust from entering to the extent that it affects the normal operation of the appliance and completely prevents touching the live or moving part of the shell.

6 Completely prevent dust from entering and completely prevent touching the live or moving part of the shell.

The meaning of the second digit after IP

0 No protection, no special protection.

1 Anti-drip, vertical drip should not enter directly into the inside of the product.

2 15゚ drop-proof, dripping in the 15-degree angle range with lead dropline should not enter directly into the inside of the product.

3 Anti-drenched water, water in the 60-degree angle range with lead dropline should not enter directly into the inside of the product.

4 Anti-splash water, splashing water in any direction should not have harmful effects on the product.

5 Anti-spray water, spray water in any direction should not have harmful effects on the product.

6 Strong waves or strong water sprays should have no harmful effects on the product.

7 Anti-immersion water, the product at a specified time and pressure immersed in water, water intake should not have harmful effects on the product.

8 Diving, the product under the prescribed pressure for a long time immersed in water, the inlet of water should not have harmful effects on the product.

8． Classified by ventilation and cooling

1. Self-cooled: The motor is cooled only by surface radiation and the natural flow of air.

2. Self-fan cooling: The motor is driven by its own fan, which supplies cooling air to cool the motor surface or its interior.

3. He fan-cooled: The fan that supplies the cooling air is not driven by the motor itself, but by itself.

4. Pipe ventilation: Cooling air is not directly from the outside of the motor into the motor or directly from the inside of the motor discharge, but through the pipe introduction or discharge of the motor, pipe ventilation fan can be self-fan-cooled or other fan-cooled.

5. Liquid cooling: liquid cooling for electric motors.

6. Closed-circuit circulating gas cooling: The medium of the cooling motor is circulated in a closed circuit including the motor and the cooler, but the medium absorbs heat as it passes through the motor and releases heat as it passes through the cooler.

7. Surface cooling and internal cooling: The cooling medium does not pass through the inside of the motor conductor called surface cooling, and the cooling medium passes through the motor conductor internally known as internal cooling.

9． Press the installation structure

Motor mounting patterns are usually represented by codes. The code is represented by the internationally installed acronym IM, the first letter of the IM represents the installation type code,B represents the horizontal installation,V represents the vertical installation, and the second digit represents the feature code, expressed in Arabic numerals.

For example, the IMB5 type indicates that the base has no base, that there is a large flange on the end cap, and that the shaft is extended at the flange end.

Installation models are B3,BB3,B5,B35,BB5,BB35,V1,V5,V6,  etc.

10． By insulation grade is divided into: A, E, B, F, H, C.

11． The rated work system is divided into: continuous, intermittent, short-term working system.

Continuous operating system(S1):The motor guarantees long-term operation under the rating conditions specified in the nameplate.

Short-term operating system(S2):The motor can only operate for a short period of time under therating conditions specified in the nameplate.  There are four duration criteria for short runs:10min,30min,60min, and 90min.

Intermittent operating system(S3):Motors can only be used intermittently and periodically under the rating conditions specified in the nameplate, expressed as a percentage of 10min per cycle. For example:FC- 25%,including S4-S10 are intermittent operating systems under several different conditions.

Represents the product

Y(IP44)series asynchronous motors

Motor capacity from 0.55to200kW,Class B insulation, protection class IP44,to the International Electrotechnical Commission(IEC)standards, products to the international level of the late   1970s, the full range of weighted average efficiency than the JO2 series increased by 0.43%,annual output ofabout 20 million kW.

Yx series of high-efficiency motors

Capacity 1.5to90kW, 2,4,6 and so on 3  poles.  The full range of motors is on average about 3% more efficient than the Y(IP44)series, close to the international advanced level. Suitable for single-directional operation with annual working hours of more than 3000h.  Where the load rate is greater than 50%, the power savings are significant. The series of motors is not high in production, with an annual output of about 10,000  kW.

Variable speed control motor

The main products are YD(0.45to160kW)inChina,YDT(0.17to160kW),YDB(0.35to82kW),YD(0.2to24kW),YDFW  (630to4000kW)and other 8 series of products, to achieve the international average application level.

Electromagnetic slip differential speed control motor

China has mass produced YCT(0.55to90kW),YCT2(15to250kW),YCTD(0.55to90kW),YCTE(5.5to630kW),YCTJ  (0.55to15kW)and other 8 series of products, to reach the international average application level, of which YCTE series has the highest level of technology, the most promising development.

The purpose app

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The most widely used of all kinds of motors is AC asynchronous motors (also known as induction motors). It is easy to use, reliable to run, low in price, solid structure, but the power factor is low, speed adjustment is also difficult. High-capacity, low-speed power engines are commonly used in synchronous motors (see synchronous motors). Synchronous motors not only have a high power factor, but also their speed is independent of the load size, depending only on the frequency of the grid.  The work is more stable. Use more DC motors when wide range speed adjustment is required. But it has a transverter, complex structure, expensive, maintenance difficulties, not suitable for harsh environment. After the 1970s, with the development of power    electronics technology, AC motor speed control technology is maturing, equipment prices are decreasing, has begun to be used. The maximum output mechanical power of the motor can bear without causing the motor to overheat under the prescribed working system (continuous, short-running, intermittent cycle operation system) called its rated power, and attention should be paid to the provisions on the nameplate when using it. When running the motor, care should be taken to match the characteristics of its load to the characteristics of the motor, so as to avoid flying cars or stopping. Motors can provide a wide range of power, from milliwatt to 10,000 kilowatts. The use and control of the motor is very convenient, with self-starting, acceleration, braking, reversal, holding and other capabilities. Generally, the output power of an electric motor changes with the speed when it is adjusted.

advantage

Brushless DC motor consists of motor body and driver, and is a typical mechatronic product. The stalect windings of the motor are made into three relative star-shaped joints, which are very similar to the three-phase asynchronous motors. The rotor of the motor is adhesioned with a magnetized permanent magnet, and in order to detect the polarity of the rotor of the motor, a position sensor is installed in the motor. The driver consists of power electronics and integrated circuits, which function as follows: accept the start, stop and brake signals of the motor to control the start, stop and brake of the motor, accept the position sensor signal and the forward and reverse signal, use to control the continuity of the power tubes of the inverter bridge, produce continuous torque, accept speed commands and speed feedback signals to control and adjust the speed, provide protection and display, and so on.

Since brushless DC motors operate in a self-controlled manner, they do not add a starting winding to the rotor like a synchronous motor that is overloaded at variable frequency speed, nor do they oscillate and stall when the load mutates. The permanent magnet of a small and medium-sized brushless DC motor is made of the rare earth ferrite boron (Nd-Fe-B)material with high magnetic energy. As a result, rare earth permanent magnet brushless motor size than the same capacity three-phase asynchronous motor reduced a seat number. In the past 30 years, the research on asynchronous motor variable frequency speed control is in the final analysis looking for a method to control the torque of asynchronous motor, rare earth permanent magnet brushless DC motor will certainly show advantages in the field of speed control with its characteristics of wide speed control, small volume, high efficiency and low steady-state speed error. Brushless DC motor because of the characteristics of DC brush motor, but also the frequency of the device, so also known as DC frequency conversion, the international common term for BLDC brushless DC motor operating efficiency, low speed torque, speed accuracy, etc. are better than any control technology inverter, so it deserves the attention of the industry. With more than 55kWof productsalready produced, it can be designed to 400kWtomeet the industry’s need for power-saving and high-performance drives.

1, a comprehensive replacement of DC motor speed control, a comprehensive replacement of the inverter and variable frequency motor speed control, a comprehensive replacement of asynchronous motor and reducer speed control;

2, can run at low speed and high power, can eliminate the gearbox directly drive large load;

3, with all the advantages of traditional DC motor, but also cancel the carbon brush, slip ring structure;

4, the torque characteristics are excellent, medium and low speed torque performance is good, the starting torque is large, the starting current is small

5, no level speed control, speed control range is wide, overload capacity is strong;

6, small size, light weight, large force;

7, soft start and soft stop, braking characteristics are good, can eliminate the original mechanical braking or electromagnetic braking device;

8, high efficiency, the motor itself does not have excitation loss and carbon brush loss, eliminating multi-stage deceleration consumption, comprehensive power saving rate of up to 20% to 60%,only save electricity a year to recover the acquisition cost;

9, high reliability, good stability, adaptability, simple repair and maintenance;

10,resistant to bumps and vibrations, low noise, small vibration, smooth operation, long life;

11,no radio interference, do not produce sparks, especially suitable for explosive sites, there is explosion-proof type;

12,as needed, choose a trapezoidal wave magnetic field motor and a positive-rotor magnetic field motor.

protection

Motor protection

Motor protection is to give the motor comprehensive protection, that is, in the motor overload,  phase absence, blocking, short circuit, overpressure, undervoltage, leakage, three-phase imbalance, overheating, bearing wear, fixed rotor eccentricity, axial run-off radial run-off, to be alarmed or protected;

Differential protection

Motor differential protection with differential speed break protection and duplex ratio differential protection with or without secondary harmonic braking, can be used for up to three-sided differential input occasions (three-lap variation), with a single device voltage current simulation and switching volume of the complete and powerful acquisition function, equipped with Standard RS485 and industrial CAN communication port, and through reasonable configuration to achieve three-lap main variable differential protection, two-lap main variable differential protection, two-lap variation differential protection, generator differential protection, motor differential protection and non-electric power protection and other protection and measurement and control functions;

Overload protection

The coils of micro-motors are usually made of very fine copper wire and are less current resistant. When the motor load is large or the motor is stuck, the current flowing through the coil increases rapidly, while the motor temperature increases sharply and the copper wire winding resistance is easily burned. If the polymer PTC thermistor can be stringed in the motor coil, it will provide timely protection against combustion when the motor is overloaded.  Thermistors are usually near the coils, making thermistors easier to feel the temperature and making protection faster and more effective. Thermistors for primary protection typically use KT250 thermistors with higher pressure resistance, and thermal resistors for secondary protection typically use KT60-B,KT30-B,KT16-B, and flaky motors with lower pressure resistance levels.

Fire hazard of electric motors

The specific causes of the motor fire are as follows:

1, overload

This can cause an increase in winding current, an increase in winding and iron heart temperatures, and, in severe cases, a fire.

2, broken phase operation

Although the motor can still operate, the winding current increases so that it burns the motor and causes a fire.

3, poor contact

Will cause the contact resistance is too large to heat or produce an arc, in severe cases can ignite the motor combustible material and then cause a fire.

4, insulation damage

A short circuit between phases and a dragonfly is formed, which causes a fire.

5, mechanical friction

Damage to bearings can cause the sator, rotor friction or motor shaft to get stuck, resulting in high temperatures or short circuits in windings that can cause fires.

6, improper selection

7, iron heart consumption is too large

Too much vortex loss can cause iron heart fever and winding overload, causing fire in severe cases.

8, poor grounding

When the motor winding pair short circuit occurs, if the ground is not good, will cause the motor shell charged, on the one hand can cause personal electric shock accident, on the other hand, cause the shell to heat up, seriously ignite the surrounding combustible materials and cause a fire.

fault

The cause of the failure

1．  The motor is overheating

1), the power supply caused the motor to overheat

There are several reasons why the power supply causes the motor to overheat:

Motor fault – repair

a,the supply voltage is too high

When the supply voltage is too high, the motor anti-electric potential, flux and flux density increase. Because the size of the iron loss is proportional to the square of the flux density, the iron loss increases, causing the iron core to overheat. The increase of flux, and cause the excitation current component to increase sharply, resulting in the increase of the copper loss of the synaut winding, so that the winding overheat. Therefore, when the supply voltage exceeds the rated voltage of the motor, the motor overheats.

b,the supply voltage is too low

When the supply voltage is too low, if the electromagnetic torque of the motor remains unchanged, the flux will decrease, the rotor current will increase accordingly, and the load power supply component in the tator current will increase, resulting in an increase in the copper loss of the winding, resulting in the fixed and rotor windings overheating.

c,supply voltage asymmetry

When the power cord is one phase off, fuse  one phase is blown, or the gate knife is used

motor

The burn on the corner head of the starting equipment causes a phaseless phase, which will cause the three-phase motor to take a single phase, causing the running two-phase winding to overheat through high current and burn up to burn.

d, three-phase power supply imbalance

When the three-phase power supply is unbalanced, the three-phase current of the motor is unbalanced, causing the winding to overheat. As can be seen from above, when the motor overheats, the power supply should be considered first. After you have confirmed that there is no problem with the power supply, consider other factors.

2), the load causes the motor to overheat

There are several reasons why the motor overheats in terms of load:

a,the motor is overloaded to run

When the equipment is not matched, the load power of the motor is greater than the rated power of the motor, then the motor long-term overload operation (i.e. small horse-drawn cart), will cause the motor to overheat. When repairing an overheated motor, it is necessary to find out whether the load power is consistent with the motor power in order to prevent blind and aimless removal.

b,the dragged mechanical load is not working properly

Although the equipment is matched, but the mechanical load being dragged is not working properly, the operating load is large and small, and the motor is overloaded and hot.

c,there is a problem with the dragging machinery

When the dragged machinery is faulty, inflexible or stuck, it will overload the motor, causing the motor winding to overheat. Therefore, when the maintenance motor overheats, the load factors can not be ignored.

3), the motor itself caused overheating causes

a,motor winding break

When there is a phase winding break in the motor winding, or a branch break in the parallel branch, it will cause the three-phase current to be unbalanced and the motor to overheat.

b,the motor winding is shorted

When a short circuit fault occurs in the motor winding, the short-circuit current is much larger than the normal operating current, increasing the copper loss of the winding, causing the winding to overheat or even burn.

c,the motor connection error

When the triangular connection motor is staggered into a star, the motor is still running with full load, the current flowing through the station winding is more than the rated current, and even causes the motor to stop on its own, if the stop time is slightly longer and does not cut off the power supply, the winding not only seriously overheated, but will also burn. When the motor connected by the star is mistakenly connected into a triangle, or when several coil groups are strung into a branch motor is staggered into two branches in parallel, the windings and the iron heart will overheat and, in severe cases, burn the windings.

e,the motor connection error

When a coil, coil group, or one-phase winding is reversed, it can cause a severe imbalance in the three-phase current and overheat the winding.

f,mechanical failure of the motor

When the motor shaft bending, assembly is not good, bearing problems, etc. , will make the motor current increase, copper loss and mechanical friction loss increase, so that the motor too  hot.

4), poor ventilation and cooling cause the motor to overheat:

a,the ambient temperature is too high, so that the air temperature is high.

b,the air inlet has debris blocking, so that the wind is not smooth, resulting in a small amount of air

c,too much dust inside the motor, affecting heat dissipation

d, fan damage or reverse, resulting in no wind or small air volume

e,not equipped with a wind cover or the motor end cover is not equipped with a windscreen, resulting in the motor without a certain wind path

2. Reasons why three-phase asynchronous motors cannot start:

1), the power supply is not on

2), fuse fuse fuse

3), the tyration or rotor winding is broken

4), the tyre winding ground

5), the synonycler windings short-circuit between phases

6), the tyre winding wiring is wrong

7), overload or drive machinery is rolled

8), the rotor copper strip is loose

9), there is no lubricant in the bearing, the shaft is expanded due to heat, hindering the swing in the bearing

10),the control equipment wiring error or damage

11),the overcurrent relay is too small

12),the old start switch oil cup is short of oil

13),the winding rotor motor start operation error

14),the rotor resistance of the winding rotor motor is not properly equipped

15),bearing damage

Three-phase asynchronous motor can not start a lot of factors, should be based on the actual situation and symptoms for detailed analysis, careful examination, can not engage in forced multiple starts, especially when the motor makes abnormal sound or overheating, should immediately cut off the power supply, in the investigation of the cause and after the elimination of the start, in order to prevent the expansion of the fault.

3. Causes of slow speed when the motor is running with load

1), the supply voltage is too low

2), rat cage rotor broken

3), the coil or coil group has a short circuit point

4), coil or coil group has a counter-link

5), phase winding back

6), overloaded

7), winding rotor one phase break

8), the winding rotor motor starting converter contact is not good

9), the brush and the slip ring contact is not good

4．  The cause of the abnormal sound when the motive is running

1), the tyrpole and the rotor rub

2), the rotor wind leaf hit the shell

3), the rotor wipe insulation paper

4), bearings lack oil

5), the motor has debris

6), the motor two-phase operation has a buzz

5. The motor housing is live for:

1), the power cord and ground wire are wrong

2), motor winding moisture, insulation aging makes the insulation performance reduced

3), lead out and terminal box shell

4), local winding insulation damage caused the wire to hit the shell

5), iron heart relaxation stab wire

6), the ground wire is not working

7), the terminal board is damaged or the surface is too oily

6． The reason why the winding rotor slip ring spark is too large

1), the surface of the slip ring is dirty

2), the brush pressure is too small

3), the brush rolled in the brush

4), the brush deviates from the neutral line position

7． The cause of the motor’s temperature rise too high or smoke

1), the supply voltage is too high or too low

2), overloaded

3), the motor single-phase operation

4), the tyre winding ground

5), bearing damage or bearings too tight

6), the tator winding between or between the short circuits

7), the ambient temperature is too high

8), the motor duct is not good or the fan is damaged

8． The cause of the current gauge pointer swinging back and forth when the motor is empty or when the load is running

1), rat cage rotor break

2), winding rotor one phase break

3), the one-phase brush of the winding rotor motor  is in poor contact

4, the short circuit device of the winding rotor motor is in poor contact

9． The cause of the motor vibration

1), rotor imbalance

2), the shaft head bends

3), belt disc imbalance

4), belt coil shaft hole eccentric

5), the ground foot screws that holdthe motor loose

6), the foundation of the fixed motor is not secure or uneven

10． The cause of overheating of motor bearings

1), bearing damage

2), too much lubricant, too little or poor oil quality

3), bearings and shafts with too loose inner circle or too tight

4), bearings and end caps with loosening the perimeter or too tight

5), sliding bearing Oil ring rolling or slow rotation

6), the end caps on both sides of the motor or the bearing covers are not flat

7), the belt is too tight

8), couplings are not well installed.

Fault repair

During long-term operation of the motor, there are often various faults: such as the connector transmission torque with the gearbox is larger, the connection hole on the flange surface appears serious wear, increasing the connection of the mating gap, resulting in uneven transmission torque;   After this kind of problem occurs, the traditional method is mainly to repair the finishing welding or brush plating after machining, but both have some disadvantages. The thermal stress generated by the high temperature of rewelding cannot be completely eliminated, it is easy to bend or break, while the brush plating is limited by the thickness of the coating and peels easily, and both methods are metal repair metal, can not change the “hard-to-hard”  relationship, under the combined action of each force, will still cause  another wear. In contemporary Western countries, the repair method of polymer composite materials is adopted. The application of polymer material repair, neither the effect of rehydration heat stress, repair thickness is not limited, at the same time the product has the metal material does not have the retreat, can absorb the impact of the equipment vibration, avoid the possibility of wear again, and extend the service life of equipment components, for enterprises to save a lot of downtime, create great economic value.

Fault:  The motor cannot be started when it is switched on

Reasons and treatment methods:

1． The terminal winding is wiring incorrectly – check the wiring and correct the error

2． The noose winding is broken, the short circuit is grounded, and the electric motivation winding around the rotor is broken – find the fault point and correct the fault

3． The load is too heavy or the drive mechanism is stuck – check the drive mechanism and the load

4． The rotary circuit of the winding rotor motor is open (bad contact between the brush and the slip ring, the inverter is broken, the lead contact is bad, etc.)- identify the break point and repair it

5． The supply voltage is too low – check the cause and rule out

6． Power phase defect – Check the line and restore the three phases

Fault: The motor temperature rises too high or smokes

Reasons and treatment methods:

1． Too heavy a load or too frequent start -reduce the load and reduce the number of starts

2． Lack of phase during operation – Check the line and restore the three phases

3． The tyre winding wiring error – check the wiring and correct it

4． The tator winding is grounded, and a short circuit occurs between the crucibles or phases — the ground or short circuit is identified and repaired

5． Cage rotor winding break – Replace rotor

6． The winding rotor windings are missing phase – find the fault point and fix it

7． The tyration rubs against the rotor – check the bearings, the rotor is deformed, and repair or replace

8． Poor ventilation – Check that the air is clear

9． Voltage is too high or too low – check the cause and rule out

Fault: The motor vibrates too much

Reasons and treatment methods:

1． Rotor imbalance – leveling balance

2． With wheel imbalance or shaft extension bending – check and correct

3． The motor is not aligned with the load axis – check the axis of the adjustment unit

4． The motor is not installed properly – check the installation and the sole screws

5． The load is suddenly too heavy – reduce the load

There is a noise at runtime

Reasons and treatment methods:

1． The tyration rubs against the rotor – check the bearings, the rotor is deformed, and repair or replace

2． Damaged or poor lubrication of bearings – replace bearings and clean them

3． Motor phase-missing operation – Check the break point and fix it

4． Wind leaves touch the case – check for and eliminate faults

The speed of the motor is too low when it is loaded

Reasons and treatment methods:

1． Supply voltage is too low – Check the supply voltage

2． Too much load – Check the load

3． Cage rotor winding break – Replace rotor

4． Winding rotor wire group 1 Poor contact or disconnect – check brush pressure, brush and slip ring contact and rotor winding

The motor housing is live

Reasons and treatment methods:

1． Poor grounding or too large ground resistance – connect the ground wire as required to eliminate the fault of poor grounding

2． Winding moisture – drying

3． Damaged insulation, lead bumps – paint repair insulation, re-join leads

Repair tips

When the motor is running or failing, it can prevent and correct the fault in time by looking, listening, smelling and touching four methods to ensure the safe operation of the electric motive.

One, look

To observe the operation of the motor is abnormal, its main performance is the following conditions.

1. When the tator winding is shorted, smoke from the motor may be seen.

2. When the motor is severely overloaded or out of phase, the speed will slow down and there will be a heavy  “buzz”  sound.

3. The motor is operating normally, but when it stops suddenly, you will see sparks coming out of the loose wiring;   Fuse fuses or a component is stuck.

4. If the motor vibrates violently, it may be that the drive is stuck or the motor is poorly secured, the solel bolts are loose, etc.

5. If there is discoloration, burn marks and smoke marks at the contact points and connections within the motor, there may be local overheating, poor contact at the conductor connection or burnout of windings.

Second, listen

The motor should be operating normally with a uniform and lighter  ”buzz”  sound, no noise and no special sound.  If the noise is too loud, including electromagnetic noise, bearing noise, ventilation noise, mechanical friction sound, etc., may be a precursor to the fault or a symptom of the fault.

1. For electromagnetic noise, if the motor makes a loud, high and low sound, there may be several reasons.

(1) The air gap between the stal and the rotor is not uniform, at this time the sound is high and low and the interval between the high bass is unchanged, which is caused by bearing wear so that the styring and rotor have different hearts.

(2) The three-phase current is unbalanced. This is the cause of mis grounding, short circuit, or poor contact of the three-phase winding, if the sound is dull, the motor is seriously overloaded or out of phase operation.

(3) The iron core is loose. The motor in operation due to vibration of the iron core fixing bolt loose, resulting in the iron core silicon steel sheet loose, making noise.

2. For bearing noises, it should be monitored frequently during motor operation. Listening method is: one end of the screwdriver against the bearing mounting area, the other end close to the ear, you can hear the bearing running sound. If the bearing is functioning normally, its sound is continuous and small “sand”   sound, there will be no changes in height and low and metal friction. The following sounds are not normal.

(1) Bearing operation has a “squeak”   sound, which is the sound of metal friction, generally caused by the bearing lack of oil, should be opened bearing filling the appropriate amount of grease.

(2) If there is a “mile”  sound, this is the sound of the ball when it  turns, generally caused by the grease drying up or lack of oil, can be filled with the appropriate amount of grease.

(3) If the sound of “kaka”  or  “squeak”    occurs, the sound is generated by irregular movement of the balls in the bearing, which is caused by damage to the balls in the bearings or long-term use of the motor, and the drying up of grease.

3. If the transmission mechanism and the drive mechanism make a continuous rather than high and low sound, can be treated in the following cases.

(1) Periodic  “popping”  sound caused by the smoothness of the belt connector.

(2) Periodic “twisted”   sound, caused by loosening between couplings or belt wheels and shafts, and by wear of keys or keyways.

(3) Uneven collision sound, caused by wind leaf collision fan cover.

Three, smell

Faults can also be judged and prevented by smelling the motor. If a special paint smell is found, the internal temperature of the motor is too high, and if a heavy paste or scorched odor is found, the insulation may have been broken or the windings burned.

Four, touch

Touching the temperature of some parts of the motor can also determine the cause of the fault. To ensure safety, when touching the back of the hand to touch the motor housing, bearings around the part, if found abnormal temperature, the reasons may be the following.

1. Poor ventilation. Such as fan shedding, ventilation duct blockage, etc.

2. Overload. Causes the current to be too high and causes the tyrone winding to overheat.

3. Short circuit or three-phase current imbalance between the tator windings.

4. Start or brake frequently.

5. If the temperature around the bearing is too high, it may be caused by damage to the bearing or lack of oil.

Variable frequency speed

The general brushless DC motor is essentially a servo motor, consisting of a synchronous motor and a driver, and is a variable frequency speed motor.  The brushless DC motor with variable voltage regulation is a brushless DC motor in the true sense of the word, it consists of styrings and rotors, stalects are made up of iron hearts, and coils are winding with   ”shun-inverse-reverse-reverse…”,    resulting in N-S   groups Fixed magnetic field, rotor consists of a cylindrical magnet (middle with shaft), or by electromagnet plus electric ring, this brushless DC motor can produce torque, but can not control the direction, in any case, this motor is a very meaningful invention. When as a DC generator, the invention can produce a dc current with continuous amplitude, thus avoiding the use of filter capacitors, the rotor may be permanent magnet, brush excitation or brushless excitation.  When used as a large motor, the motor will produce a sense of self,900 and a protective device is required.

Domestic development

Relevant statistics show that the largest increase in the output of general products, other derived special series of motor products also have a larger increase, for example, vibration motors, vibration sieve motors, variable frequency motors, elevator motors, submersible oil motors, injection molding mechanical and electrical motivation, permanent magnetic synchronous motors,  AC servo motors and so on. New product development has also achieved remarkable results.  The “Hot and Cold” Y3 series three-phase asynchronous motordeveloped during the  “Fifth Five-Year Plan” period has passed the expert appraisal in April2002  and is being promoted nationwide. In addition, in the main derived series of cold-rolled silicon steel sheet replacement product development work is also under way, such as high-efficiency motor series, low noise low vibration motor series, low-voltage high-power motor series,IP23 low-voltage motor series.

With the increasing competition in the motor manufacturing industry, the merger and acquisition integration and capital operation among large-scale motor manufacturing enterprises are becoming more and more frequent, and the outstanding motor manufacturing enterprises at home and abroad pay more and more attention to the research on the industry market, especially the in-depth study of the development environment and the trend of customer demand. Because of this, a large number of domestic and foreign excellent motor brands quickly rise, and gradually become the motor manufacturing industry leader.

Industry experts pointed out that during the “Fifth Five-Year Plan” period, due to the rapid development of the national economy, the output of small and medium-sized electrical products than the original “Fifth Five-Year Plan” proposed a relatively large growth plan.

There’s more to it than that. Industry integration accelerated, small and medium-sized motor industry integration of the curtain has been opened. There are nearly 2000 electrical plants, large and small in China, and although the number of enterprises is huge, quite a number are small enterprises. Experts pointed out that due to the large number of manufacturers, large production, forming a mutual preemption of the market price competition situation. Product quality is uneven, mutual price competition, industry profits are meager and other phenomena, has become the main reason affecting the survival and development of motor enterprises.

The motor itself is a labor-intensive product, not up to a certain production scale is difficult to produce benefits, so the industry profit is very small, the national motor industry employs about 300,000 people,in2003 the industry realized a profit of only 280 million yuan. It is understood that even in some of the more efficient enterprises, the net profit is not up to 5%.  At the same time, because most small enterprises production process is not close, the motor industry still has a large number of product quality failure phenomenon. According to the survey, China’s motor enterprises scrap, inferior products, repair products and other adverse losses on average in about 10%, while foreign industrial developed countries of motor enterprises generally fail the level of 0.3%.

In recent years, China’s electrical industry has also emerged a number of large-scale production, product level, good quality, advanced technology and equipment enterprises. However, no one has a dominant share of the domestic market. Small and medium-sized motors have not yet formed an international influence of the brand. The motor industry urgently needs to be re-integrated, the survival of the fittest, which has become the development trend of the motor industry.  Experts pointed out that although the motor industry is an old traditional industry, but all walks of life supporting motors are indispensable. Moreover, some large electrical enterprises cover a large area, located in a good location, after the merger, will bring the acquirer very rich benefits and financial resources.

Environmental policy

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In order to implement the   “12th Five-Year Plan” of the State Council, the Opinions on Speeding Up the Development of Energy Conservation and Environmental Protection Industry, and the Analysis Report on the Forecast and Transformation and Upgrade of Production and Marketing Demand of China’s Electric Motor Manufacturing Industry, guide the production and promotion of energy-saving mechanical and electrical equipment (products), combine the actual energy-saving and emission reduction work of industry and communication industry, and be recommended, expert review and publicity by the competent departments of industry and information technology and related industries in various places.   The Catalog covers a total of 344 models in 9 categories.  Among them, transformers 96 models, electric motors 59 models, industrial boilers 21 models, welding machines 77 models, refrigeration 43 models, compressors 27 models of products, plastic machine 5 models, fan 13 models, heat treatment 3 models.

The Directory is valid for three years from the date of publication. During the validity period, if there is a major innovation in product technology and a major change in evaluation standards, the enterprise shall re-declare. ^[2]

Precautions

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(1) Before removal, blow the dust off the surface of the motor with compressed air and wipe the surface dirt clean.

(2) Select the location where the motor disintegrates and clean up the field environment.

(3) Be familiar with the characteristics of the motor structure and the technical requirements for maintenance.

(4) Prepare the tools (including specialized tools) and equipment needed for disintegration.

(5) In order to further understand the defects in the operation of the motor, a check test may be carried out before removal when conditions are in place. To this end, the motor will be load test, detailed inspection of the motor parts of the temperature, sound, vibration and other conditions, and test voltage, current, speed, etc. , and then disconnect the load, a separate empty load inspection test, measured the empty current and empty load loss, do a good record.

(6) Cut off the power supply, remove the external wiring of the motor, and make a good record.

(7) Test the motor insulation resistance with a meE meter with the right voltage. In order to compare the insulation resistance values measured at the last service to determine the motor insulation trends and insulation status, the insulation resistance values measured at different temperatures should be converted to the same temperature, generally to 75degrees C.

(8) Test absorption ratio K. When the absorption ratio is greater than 1.33, the motor insulation is not damped or is not severely damped. In order to compare with previous data, the absorption ratio measured at any temperature is also converted to the same temperature.