what happens when an electric motor is overloaded?
overloading a motor cause excessive current in the motor winding and could result in damage to the motor due to the beat generation by the product of the motor voltage motor current.
if it is overloaded on the output shaft, i.e, trying to move something too heavy, the motor will begin to stall and will eventually burn up. Turn it off immediately. If it is overloaded by current, it will also burn up and become unusable. Again, turn it off immediately.
When an electric motor is overloaded, its stator windings will overheat, and its overload relay should trip after 5 minutes. If not, the motor may overheat and it' wiondings will burn.. For this reason, a good maintenance practice is to calibrate the thermal overload relays annually and see that it trips on its current setting.
When an electric motor is running nomally, it will be generating electricity as well. This generated electricity will oppose the power supply to the motor, and thus decrease the current being consumed by the motor. This is known as Back EMF (Electro Motive Force). If the motor is then overloaded it will slow down. This will decrease the ammount of Back EMF being generated, and so the current will increase dramatically. This will cause overheating, depending on how much the motor is overloaded. If it is stalled, it may well catch fire. Air cooling the motor, using perhaps a fan, will help the situation.
An overloaded AC electric motor will begin to slow down and draw more current than normal. This will cause internal overheating. Most good general purpose motors have an internal high temperature thremostat that will shut them down before any serious damage is done. When the motor has cooled it can be restarted; however, it should not be continued to be operated that way because it will soon fail anyway. The thermostat will likewise stop the motor if the cooling air passages are obstructed and the motor overheats.
