Ex-P Motor Tripping on Start 1

[claudenir]

I need some tips regarding an air purge system installed in a Ex-P motor.

Motor Data
Power: 6100kW
Poles: 4P
Frame: IEC800

Purge System Data
Expo D758 Electronic Timer

The Problem
Right after the purge time, the motor is started and occasionally the motor trips due to low pressure inside the frame. We are facing this problem for quite some time and we are running out of ideas to solve it. Can anyone give me some tip on what to look for?

If more information is required, I will gladly inform.

 

[Compositepro]

There must be an internal fan (or the rotor is behaving as a fan). This will affect the pressure distribution inside the motor. I would suggest that you have set the purge flow rate too low and that the positive pressure in the motor is too close to the trip point setting.

 

[claudenir]

How can I increase the purge flow rate? I know that I can increase the pressure inside the motor adjusting the CLAPS valve, but how about the purge flow rate?

 

[Compositepro]

The valve controls purge flow directly. Pressure is indirectly controlled by the resistance of the leak paths out of the motor to the air flow into the motor. So, if some cover were not properly tightened, that could also cause a problem.