Wiring method of motor protector

Motor protector

The function of the motor protector is to provide comprehensive protection and control for the motor. It will give an alarm or protective control when the motor has overcurrent, undercurrent, phase failure, stall, short circuit, overvoltage, undervoltage, leakage, three-phase imbalance, overheating, grounding, bearing wear, stator and rotor eccentricity, or winding aging.

Motor protector

(I) The thermal relay is a metal sheet mechanical motor overload protector developed with Soviet technology in the early 1950s. It has the characteristics of inverse time performance and simple structure in protecting motor overload. However, it has few functions, no phase failure protection, and does not protect the motor from poor ventilation, sweeping, stalling, long-term overload, frequent starting and other faults. This is mainly because the thermal relay action curve is inconsistent with the actual protection curve of the motor, and the protection function is lost. In addition, the repetitive performance is poor, and it cannot be used again after a large current overload or short circuit fault. It has large adjustment errors, is easily affected by the ambient temperature, malfunctions or refusing to operate, has high power consumption, many consumables, and backward performance indicators.

(II) Temperature relays are disc-type or other types of relays made of bimetallic strips. They have the advantages of simple structure, reliable operation, and wide protection range. However, they are slow to operate and take a long time to return. They are not suitable for use with delta-connected motors above 3KW. Nowadays, they are widely used in electric fans, refrigerators, air-conditioning compressors, etc.

Temperature relays are different from thermal relays. Temperature relays are installed inside the motor and are activated by temperature changes, while thermal relays are installed on the power line and are activated by the thermal effect of current.

(III) Electronic motor protectors have evolved from transistors to integrated circuits and now to microprocessor chips and thick-die circuits. They are generally divided into phase failure protection, comprehensive protection (multi-function protection), temperature protection and intelligent protection in terms of function. This type of protector has the advantages of energy saving, sensitive action, high precision, impact and vibration resistance, good repeatability, complete protection functions and low power consumption.

1. The motor protector (motor protector) is based on the principle of detecting changes in line current (including positive sequence, negative sequence, zero sequence and overcurrent), and can detect phase loss or overload signals. In addition to the phase loss protection function, it also has overload and stall protection functions.

2. Intelligent protection: The motor protection device integrates protection, telemetry, communication and remote control. It can protect the motor when it is broken, overloaded, short-circuited, under-voltage, over-voltage and leakage. It also has current and voltage display, time control, software self-diagnosis, call recovery, self-starting sequence, fault memory, self-locking and remote alarm. It can display the current and voltage when the fault occurs, and use the code to flash before and after the fault to warn. It is equipped with RS485 communication interface to realize computer networking. It can monitor and monitor the operation of 256 motors at the same time.

Wiring method of motor protector

Connect the a, b, c phase wires of the main circuit to the primary terminals of a, b, c phase current respectively; connect the l and n terminals of the motor protector to the ac 220v power supply; connect the o11 and o12 terminals of the motor protector in series

Connect to the motor control coil loop; use wires to connect ia1, ia2, ib1, ib2, ic1, ic2 to the a, b, c phase secondary terminals respectively; connect the voltage to be detected to the v1, v2 terminals.

do1-do8, di1, connection and switch principle are as shown in "ampere-x/f531 series motor protector do connection relay electrical principle diagram"; connection electrical principle is as shown in "ampere-x/f531 series motor protector do

Connection PLC electrical schematic diagram" shown.

It is particularly important to note that when the motor is running, the ia1, ia2, ib1, ib2, ic1, and ic2 wires connecting the main unit and the secondary terminals of the current transformer must not be disconnected.

In the "Electrical Schematic Diagram of AMD-X/F531 Series Motor Protector DO Connection Relay", KA1-KA8 is the relay coil connected to DO1-DO8. The resistance of each coil should be greater than 300ω. Since there is freewheeling inside DO1-DO8,

Therefore, ka1-ka8 do not need to be connected with freewheeling diodes. dc+ and gnd are the positive and negative terminals of dc 24v provided by the external motor protectors di and do. k1 is the contact point for clearing the fault state switch. When the motor fails, k1 closes.

By disconnecting it again, the fault state held by the motor protector can be cleared and the motor can be restarted.

In the "AMDP-X/F531 Series Motor Protector DO Connected to PLC Electrical Schematic Diagram", the motor protector's DO1-DO8 are connected to the PLC input module's DI1-DI8 channels, and the motor protector's DI1 is connected to the PLC output module's DO1 channel.

The common terminal com1 of the plc input module di1-di8 is connected to the positive pole of dc 24v, and the common terminal com2 of the plc output module do1 is connected to the negative pole of dc 24v.

The do1 of the plc output module should normally output a low level, which has no effect on the di1 of the motor protector. When the motor fails, do1 outputs a high level and then a low level (positive pulse) to clear the motor protector fault state.

Can be restarted.

When the motor is not faulty, the do1-do8 of the motor protector outputs a high level. When the motor is grounded, short-circuited, phase-lost, stalled, overloaded, unbalanced, over-voltage, or under-voltage, the di1-di8 of the PLC input module does not have a fault signal input, and the motor is

When a voltage fault occurs, the corresponding fault type output signal (one of do1-do6) and the fault warning output signal do7 output low level, the di1-di6 of the plc input module have corresponding fault signal inputs, and the di7 inputs fault warning signals.

It lasts until the set alarm time, the fault alarm output signal do8 outputs a low level, and the di8 of the plc input module inputs a fault alarm signal.