If the motor is blocked for a long time, it will burn out. This is a problem often encountered in the production process, especially for motors controlled by AC contactors.
I saw someone on the Internet analyzing the reason, which is that after the rotor is blocked, the electrical energy cannot be converted into mechanical energy and burned. That’s a bit profound.
Let’s explain it in layman’s terms, so that if you encounter this kind of thing at work, the boss asks why the motor burned out, without using layman’s terms.
Then come up with feasible methods to prevent the motor from stalling, ensure the safety of the motor, save the company money, and your work will be smoother.
1. The motor transmission methods supporting the equipment are different, and the motor protection measures are different. If the triangular transmission motor encounters excessive load or stalling, the triangular belt will slip to protect the safety of the motor and equipment. The power distribution control circuit is then used. Thermal relay protection or special motor protector.
There is a misunderstanding here. When an operator encounters a stall for unknown reasons, instead of cleaning the equipment and solving the cause of the stall, he starts it repeatedly. Since the thermal relay protection trips, if it cannot start, he manually resets it and starts it again, so that the motor will be very fast. It burned.
After the rotor is blocked, the current can increase several times or ten times. If the rated current of the motor exceeds too much, the winding will be burned out. Or it may break down the insulation layer, causing a short circuit between phases or a short circuit to the shell.
The motor protector is not a panacea. To avoid burning the motor, it is necessary to use a protector and strictly implement safe operating regulations. If the cause of the stall is encountered, the motor cannot be turned on repeatedly without eliminating the cause of the stall.
If you want to be lazy and don’t clean the equipment, continuous forced starts will burn the motor.
2. With the development of technology, frequency converter control has become commonplace. These high-tech controls have an additional layer of protection compared to AC contactor control. The frequency converter automatically protects against overload or short circuit, and does not eliminate the hidden dangers of stalling or short circuit. If you start repeatedly No.
So this kind of circuit will not burn the motor?
No protection measures are omnipotent. After the inverter is blocked and tripped, a smart operator or an electrician who doesn’t know much will directly reset the inverter and start it again. After a few more attempts, the inverter will burn out and remain broken. The frequency converter cannot control the motor.
Or artificial reset forces several starts, causing the motor to overheat and burn out.
Therefore, it is common for motors to stall, but burning the motor means improper operation. Avoid improper operation to avoid burning the motor.
3. Work hard on motor control to ensure the safe operation of the motor. The thermal relay and motor protector should be tested regularly to see if the control circuit can be disconnected. There is a red button on the thermal relay. Press it during regular test runs to see if it can disconnect. Open the line.
If it cannot be disconnected, it must be replaced in time.
In addition, check whether the motor thermal relay, the adjusted setting current and the protected motor’s rated current match before starting the machine every day, and they cannot exceed the motor’s rated current.
4. The selection of motor power circuit breaker should be based on the rated current of the motor. It cannot be too large. If it is too large, it will not provide short circuit protection.
5. Prevent the motor from running out of phase. It is not uncommon for the motor to burn out due to lack of phase. If the management is not in place, it will easily happen. Before starting the machine, use a multimeter to check the motor power supply to see if the three-phase voltage is consistent and determine whether the power supply voltage is normal.
After starting up, use a current clamp meter to measure the three-phase current of the motor to see if it is balanced. The three-phase currents are basically the same and there is not much difference. Since the three phases are not measured at the same time, the current is different due to the load.
This can eliminate the motor phase loss operation in advance.
Post time:
Dec-04-2023