The 380V motor is not operating properly
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The motor stops working after 5 minutes of operation. Its power is 18.5 kilowatts; the voltage drops to 250V, and the current rises to 160A. What could be the problem? Urgent help needed. Additionally, a 10-kilowatt motor is working normally. Last edited by hldzgb on 2009-3-16 at 20:13
I think there must be a fault; it can’t operate in such a condition, otherwise the motor will get damaged. It’s possible that 1. the motor is missing a phase – use a multimeter to check whether the three-phase windings are functioning properly. 2. A fault in the bearing or other machinery causes the motor to stall, resulting in an increase in current and rising temperature. Check the mechanical transmission part. 3. There is a fault in the power supply section, such as missing phases or abnormal voltage, etc.
The situation described by the poster is likely due to a phase loss fault; the absence of one of the three phases in the power supply can cause an increase in voltage and current. A 18.5 kW system should be started using reduced voltage, and it’s possible that there was no phase loss during startup, but after startup, phase loss occurred while the system was operating normally, resulting in a sharp rise in current. The system should be stopped immediately for inspection and repair. http://www.wnaomm.cn/index.php?46241-1.html
The voltage drop has gone down to 250; I can’t figure it out. There is definitely a voltage drop caused purely by the high current, but it’s impossible to estimate its magnitude. . 18.5 Motor. The rated current is around 37A; at 180 right now, it’s roughly 5 times that amount. . Approaching the starting current (5~7 times is normal for starting). It doesn’t exceed 10 times), and my analysis is that the motor is stuck in a locked rotor condition. . I want to calculate it. But many parameters are missing. . Cable model specifications (6 square? ）? Line length?
It’s likely that there’s a fault with the equipment; a stall is a probable possibility
You can first disconnect the three-phase wiring of the motor, then turn it on to check whether the three-phase voltages are normal. If they are not normal, it is likely that poor contact in the contactor is causing insufficient voltage, or there may be a problem with the circuit breaker. If the voltages are normal, then it’s undoubtedly a problem with the motor itself. You can’t repair the motor by yourself, so just replace it
The normal operation of the 10KW motor indicates that the power supply system is functioning properly. The 18.5KW unit stopped functioning properly after 5 minutes; 1. There was a short circuit in the motor windings, resulting in a significant increase in temperature. 2. Motor bearing damage, abnormal noise. 3. Stalling at the output shaft end, with a significant drop in speed. All three of the above cause an increase in current. If the power supply capacity is too low, the voltage drops. Please check and rule out them separately.
Cause analysis: 1. If the motor has experienced low voltage and high current from the moment it started until this point of 5 minutes, it may be due to a loose connection in the power supply; a phase loss fault has not yet occurred. The machine must be stopped immediately to check the power supply and motor circuits. 2. If startup is normal but this phenomenon occurs later, it may be due to a sudden significant increase in load, combined with a small capacity in the power supply circuit, resulting in excessive voltage drop. The machine must be stopped to check the load.
We once dealt with a similar issue involving a 250kW motor. It started up normally, but the current level rose sharply once it was operating properly. By using a clamp ammeter to check each phase, we found that no current was flowing through one of the phases. Upon stopping the machine for inspection, we discovered that the contacts of the contactor were damaged; after replacing them, everything returned to normal. A motor with a missing phase cannot operate for long periods, as this will damage the motor; there is enough time to check for the fault. http://www.wanomm.cn/index.php?46241-1.html