Can a Loss of 30 Volts Cause an Electric Motor to Overheat?

In summary, the conversation discusses a problem with a motor running hot due to a 30 volt loss of power from the generator. It is suggested to check the overload relays, motor insulation, and generator frequency to find a solution for the problem.
  • #1
Joe P
2
0
Hello, looking for some information on electric motor theory for a problem I encountered on a friends machine. An on site generator is our power supply, our motor requires 480v/ac 3phase, our generator is providing 500v/ac but we are losing 30 volts under load from our extension leads. our motor is running very hot but not tripping overload relays. My question is - could the 30 volt loss of power cause this problem. Also if I increase the voltage output on my generator will it solve the problem. Thanks joe
 
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  • #2
Without knowing how the overload relays are sized, the mechanical load and current drawn by the motor vs. the nameplate max current it is hard to recommend anything. Accepting 30 volts of loss in the wiring is not exactly good practice even if it does put the voltage at the motor right where you want it. Also, 'very hot' is a relative term. It can depend on if the motor is ventilated in the way that the designers intended.
 
  • #3
Is it possible the motor has a problem? If so, maybe that's where the 30 volt drop is coming from.
 
  • #4
Presuming the overload protection is suitable set on then the current it is in its correct limits. Elevated voltage could raise the no-load current-this could be checked of course. Usually the rated voltage is 460 V so 500 V [if this is the measured voltage at motor terminals] but 8.7% more it is not so elevated voltage.
The motor could be “very hot” if the insulation permits this. Insulation class H permits a conductor temperature of 180 dgr.C and 70-80 dgr.C outside stator surface could be permissible.
However the overload protection does not “protect” the motor against a defective ventilation or if a heat source in vicinity may deliver a substantial heat –even sunshine or else.
 
  • #5
Joe P said:
our motor is running very hot but not tripping overload relays.

Hi Joe P. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif

Check that the generator is matched to the motor's frequency, e.g., both 60Hz.
 
Last edited by a moderator:
  • #6
Thank you for the the helpful info, We are going to take more readings and check the motor tag specifications,
Thanks all Joe
 

Related to Can a Loss of 30 Volts Cause an Electric Motor to Overheat?

1. What causes an electric motor to overheat?

There are several potential causes of electric motor overheating. These include excessive load on the motor, inadequate cooling, poor ventilation, high ambient temperature, and low voltage supply. It is important to identify the specific cause in order to address the issue effectively.

2. How can I prevent my electric motor from overheating?

There are several steps you can take to prevent your electric motor from overheating. These include ensuring proper ventilation and cooling, using the correct size and type of motor for the load, avoiding excessive starts and stops, and maintaining the motor regularly. It is also important to monitor the motor's temperature and address any issues promptly.

3. What are the signs of an overheating electric motor?

Some common signs of an overheating electric motor include excessive noise, vibration, or burning smells coming from the motor, as well as frequent tripping of the motor's overload protection. If you notice any of these signs, it is important to address the issue immediately to prevent further damage to the motor.

4. Can an electric motor be repaired if it has overheated?

In some cases, an electric motor can be repaired if it has overheated. This will depend on the extent of the damage and the availability of replacement parts. However, it is important to address the issue as soon as possible to prevent further damage and potentially costly repairs.

5. Is it safe to use an electric motor that has overheated?

No, it is not safe to use an electric motor that has overheated. Continuously operating the motor in an overheated state can cause further damage and potentially lead to a motor failure or even a fire. It is important to address the issue and properly repair or replace the motor before using it again.

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