Ground pick up settings-Transformer
Ground pick up settings-Transformer
(OP)
What's the rule to choose the ground pick up current for transformer protection?
I choose phase pick up current at 166% of ONAN rating. Transformer has ONAF rating too.
I choose phase pick up current at 166% of ONAN rating. Transformer has ONAF rating too.






RE: Ground pick up settings-Transformer
For a delta winding, any ground current is generally a bad sign for the transformer, so settings are more sensitive.
The phase overcurrent pickup setting is generally determined by the maximum forced-cooled rating of the transformer.
David Castor
www.cvoes.com
RE: Ground pick up settings-Transformer
Transformers are delta-wye.
Is there a safe way to set the ground pick up current?
may be set it at transformer FLA?
RE: Ground pick up settings-Transformer
Rafiq Bulsara
http://www.srengineersct.com
RE: Ground pick up settings-Transformer
166% Of a pickup for ground fault sounds very high to me. I have worked on plant where the max ground fault is less than the max onan rating of the transformer.
Ther is no rule as such, and so much depends on the expected Earth fault current.
Another key is how is the ground fault measured, is it a core balance CT, or is the ground fault measure by the residual current from the three phase CT's. If it is the latter you need to allow for magnetising currents as well.
Or are you looking at Residual Earth Fault protection of a CT?
you need to look at the equipment that is being protected, what is it expected load range.
What is the damage curve of the transformer?
Are there cables also protected by this device?
What is their damage curve.
What is the protection of the upstream and downstream devices.
Along with a lot of others
So unless you have expreiece in this type of work you need to get someone who does to help.
RE: Ground pick up settings-Transformer
My question is more toward setting the ground pick up setting of primary side of a transformer.
Thanks for all inputs
RE: Ground pick up settings-Transformer
RE: Ground pick up settings-Transformer
RE: Ground pick up settings-Transformer
RE: Ground pick up settings-Transformer
Did you mean 160%?
RE: Ground pick up settings-Transformer
RE: Ground pick up settings-Transformer
Dave
David Castor
www.cvoes.com