[Electrical Introduction] Knowledge of intelligent motor protectors, essential for high-power motor protection

The product takes the microcomputer controller (MCU) as the core component, detects the current through high-precision CT, and the motor protector has the function of automatic linear correction; it can also realize alarm and event recording.

The protection function of the intelligent motor protector:
1. Blocking protection: During the starting process of the motor, if the motor shaft is stuck due to excessive load or mechanical reasons, and the fault is not removed in time, the motor will be overheated, the insulation will be reduced and the motor will be burned, and the locked rotor protection is applicable. Fault protection for motor starting.

2. Phase failure protection: During the normal operation of the motor, the protector can automatically detect the difference between the three-phase currents and perform phase failure action protection.

3. Overload protection: When the motor is overloaded, when the protector detects that the motor is overloaded, the protector should issue an alarm or trip signal within the set time of alarm or trip (delay).

4. Under-voltage protection: In some applications, when the voltage of the motor drops below the rated voltage, it is required to automatically cut off the power supply and stop working. This protection is called under-voltage protection.

5. Overcurrent protection: Incorrect starting and excessive load torque often cause excessive overcurrent in the motor. Generally, when the motor circuit current is between 1.5 and 6 times its rated current, the protector will reverse the current. Time limit overcurrent protection, the overcurrent protection time is generally a few seconds.

6. Three-phase current unbalances protection: When the three-phase current of the motor is seriously unbalanced, if the unbalance rate reaches the protection setting, the protector will protect according to the set requirements and issue a stop or alarm to ensure the operation of the motor.

7. Locked-rotor protection: During the starting process of the motor, if the motor shaft is stuck due to excessive load or mechanical reasons, and the fault is not removed in time, the motor will be overheated, the insulation will be reduced, and the motor will be burned.

8. Leakage grounding protection: For neutral point insulation or small current grounding systems, leakage protection will act when the zero-sequence current detected by the zero-sequence reactor exceeds the set value.

Features of Smart Motor Protector:
It has the characteristics of high-cost performance, complete functions, stable and reliable work, high precision, accurate protection action, simple and convenient installation, and parameter setting.
Application scope of intelligent motor protector:
It is suitable for the protection and monitoring of industrial three-phase motors and other electrical appliances in machinery, metallurgy, building materials, chemical industry, textile industries, etc.

Precautions for smart motor protectors:
1. Before use, the meter needs to be powered on for 15 minutes.
2. If the signal is accompanied by high-frequency interference, try a low-frequency filter online.
3. If there is no display on the meter, you should first check the auxiliary power supply to see if the voltage is within the range.
4. When not in use for a long time, please turn on the power for no less than 4 hours every three months.
5. Long-term storage should avoid direct light, and should be stored at an ambient temperature of -25°C~55°C.
6. To calibrate the instrument, the calibration instrument should be better than 0.1 to ensure calibration accuracy.
7. If the display is abnormal, check whether the input signal is normal and whether the signal terminals are tightened.
8. The input wire should not be too long. If the input end of the signal under test is long, please try a twisted pair of shielded wires.
9. The screws of the current terminals in the CT circuit must be tightened to ensure reliable contact between the incoming and outgoing wires to avoid malfunctions.
10. Unless the PT has enough power, the PT signal cannot be used as an auxiliary power supply at the same time to ensure the normal operation of the instrument.

Since its establishment in 1989, Naidian Group has always focused on the field of intelligent power systems. It has a qualified team of experts with rich R&D experience, strict new manufacturing technologies, and a complete production management system. All products have passed CCC, CE, UL, and other certifications.