3.3 KV Vacuum Pump motors Tripping

[AbrarAhmad]

Dear All
I am working in Pulp and Paper Mill where we have vacuum system comprising 3.3 KV vacuum pump- motor combination. These are tripping frequently with IE>> fault(Earth Fault). Kindly help if there is any CT fault.

 

[waross]

1> You may have a ground fault developing in one or more motors.
2> Your trip settings are too sensitive.
3> All of the above.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[zaza123]

1. Disconnect the cables & check the Motor for Earthfault
2. Check Cable healthiness
3. Check Relay healthiness.

Is there ane VFD for those motors

 

[slavag]

Hi.
Please send us ( or explain) what is CT connection to protective relay-core balance, residual connection
Please attach setting of IE>> too.

And..of course check primary ( what Bill ans zaza123 wrote), is possible a real fault.
Good Luck.
Slava

 

[RRaghunath]

Abrar Ahmad,

If the protection is connected to core balance CT, many a time the trip problem is due to the incorrect way the power cable armour is taken through the core balance CT.
Correct method is the armour that passes through the CBCT should be returned through the CBCT before connecting to earth flat.

Please post feedback once you solve the problem.

 

[1000V]

Hey Abrar, What paper mill are you working at? I am an industry nerd lol. I worked at ayelsford mills for ten years and like to keep track of the paper industry.

P.S I assume you have checked entire circuit for health. What protection system are you susing? IQ, MM, Allenwast???

 

[AbrarAhmad]

Dear 1000V,
Now the situation is under control. We have changed the Earth settings also the new CTs have been ordered. They will reach our mill in 1 months time. I am working in Bulleh Shah Paper Mill Kasur Pakistan. They have their one mill at Lahore Pakistan named Packages Limited Lahore.

 

[zaza123]

Abrar Ahmad
Did you found out any reason why it was tripping.At present the motor is running or r u waiting for CT

 

[AbrarAhmad]

Dear Zaza,
Yes Our Senior Person helped us and we found that CTs were not Ok. So we used the CT of another HT motor. While its CTs were placed on order.Vacuum Pump is now running while the other HT motor is stopped due to process people does'nt need that motor in their process and they will run the other jobs on paper machine.

 

[rmw]

Assuming that these big vacuum pumps are in the paper machine area, as 'wet' as the atmosphere is in that area, I'd do an insulation check as WaRoss has recommended on the motor(s) in question anyway to just make sure that you weren't getting an early indication of an impending fault due to wet or faulty insulation. Especially if this was for one of the pumps that doesn't run as much as the others do such as a stand-by pump.

rmw