PDC
PDC
(OP)
A core balance ground ct connection was used in O/L in a Motor,
while residual ground CT connection was used for O/C at the secondary side of Transfomer going to the switchgear where the motor connected.
My question is, can I coordinate the two relays?
What is more sensitive during ground fault?
Thank you.
while residual ground CT connection was used for O/C at the secondary side of Transfomer going to the switchgear where the motor connected.
My question is, can I coordinate the two relays?
What is more sensitive during ground fault?
Thank you.






RE: PDC
RE: PDC
One additional comment:
Your core-balance CT's are likely much more sensitive than your residually connected phase CT's. You may want to check the amount of ground fault current available to ensure that the residually connected phase CT's respond properly.
For example, 2000/5 Ct's connected residually may not allow your relaying to detect a 10A ground fault on a HRG system, but a 50/5 core balance CT would perform very well.
RE: PDC
RE: PDC
No problem with coordination.
You can put with core-balance CT a low setting..it will about 1% of In of CT ( of course all depend on ) , but with residual connection not less 10-12% of CT rating. Core balance isn't sensetive to CT mismatch, to partial saturation..for example in case of motor start.
That menat, coordination by current setting and by time setting. Standart configuration.
Good Luck.
Slava