Motor Overload Problems
Motor Overload Problems
(OP)
Hi,
A motor i was working on today started, then after about 0.1 seconds trips on "start-up current" the motor FLC is 100Amps and its start up in rush is 600Amps but the overload unit doesn't give the motor a chance to get upto running speed to allow the inrush current to drop. The motor spins free.
Sounds like the overload unit is buggered to me any other input from people much appreciated.
A motor i was working on today started, then after about 0.1 seconds trips on "start-up current" the motor FLC is 100Amps and its start up in rush is 600Amps but the overload unit doesn't give the motor a chance to get upto running speed to allow the inrush current to drop. The motor spins free.
Sounds like the overload unit is buggered to me any other input from people much appreciated.





RE: Motor Overload Problems
RE: Motor Overload Problems
Be careful with making this change however. The motor is ultimately the determining factor on which Class to use. Using a longer time curve overload block than the thermal rise time of the motor will permit simply fails to properly protect the motor.
RE: Motor Overload Problems
respectfully
RE: Motor Overload Problems
RE: Motor Overload Problems
You said that the motor tripped on start (1/10 second?) after it ran. I'm not sure it ran, other than the inrush moved the rotor. I'm assuming it tripped the supply breaker on instantaneous. If that is correct, it tripped at the supply breaker, so that rules out overloads.
If I am correct in my interpretation of your issue, you may need to test or replace your supply breaker or, you could have moisture in your motor which you could try and bake out.
If I am incorrect in my interpretation, I appologize.
12fish
As Iron Sharpens Iron, so does a man sharpen the coutenance of his friends.
RE: Motor Overload Problems
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: Motor Overload Problems
Regards,
GGOSS