pushing currents thru CT secondary with Live voltage
pushing currents thru CT secondary with Live voltage
(OP)
If I push currents from CT secondary to test my relays for overcurrent, with the substation energized (26KV) with no load, does that CT secondary current show up on the primary? Even if it does or doesn't , is there any other thing i should be worried about?






RE: pushing currents thru CT secondary with Live voltage
Do you have any test switches or shorting terminal blocks in the CT circuit where you could isolate the relay while still shorting the CT?
Is the relay in a draw out case so you could bench test it or at least remove the test plugs and inject currents at the relay?
I don't have time now to think this through, but I would be very concerned about damaging the CT, the switchgear or yourself trying to inject current in a live CT. I'll let some other experts suggest ways of doing it.
RE: pushing currents thru CT secondary with Live voltage
If you connect up to the secondary almost the current would go toward the relay, not the CT primary.
RE: pushing currents thru CT secondary with Live voltage
RE: pushing currents thru CT secondary with Live voltage
Alan
RE: pushing currents thru CT secondary with Live voltage
You should absolutely not mess around with CT secondary leads even if there is "no load" on the primary. You might just accidentally get onto the wrong CT or be into the wrong panel and open circuit a secondary and get killed. I know of a site many years ago where this actually happened to a young engineer.
Regarding back energizing of CT secondaries: It will take a up to a couple hundred Volts to get a enough mA through if the pri side is open. See tests for "Mag Curves" and "Knee Point" where such a test can be required for certain protections. i.e. Generator Differential.
Be very safe in HV installations. Only one mistake is allowed, better none.
rasevskii
RE: pushing currents thru CT secondary with Live voltage
RE: pushing currents thru CT secondary with Live voltage