Flex_CT uses
Flex_CT uses
(OP)
I would like to know what would be the possible safety issues in using a common CAT IV flex-CT (Rogowski) around a 34.5kV insulated cable (not exposed). Theoretically I understand that the amount of current through a 34.5kV is not so high, but during a fault this may change. Is it more of an accuracy issue with the reads, BIL , or is it really a hazard? I understand the cable might be punctured too. I would like to thank you in advance for any help.






RE: Flex_CT uses
It is very common to utilize CTs that are not fully rated for the "primary circuit' voltage. Most donut-type MV switchgear CTs are nominally rated 600V (by themselves), but rely on other means to provide the required insulation. As long as the Rogowski coils are installed around the non-shielded but insulated portion of the power cable, and not the bare conductors, you will be OK. I assume that the coils has UL or some other recognized form of approval.
GG
"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)
RE: Flex_CT uses
RE: Flex_CT uses
Thank you @GroovyGuy, this was what I imagined. Now bacon4life got me curious:
@bacon4life Aren't most of UG cables shielded, though? Reading upon it, I found that it is to decrease inductive reactance. Follow-up: Do you know how shielding decreases the inductive reactance (I have no clue, maybe reduce the magnetic flux)? And how is that a big safety hazard (not being shielded) in the Flex-CT scenario?
Thanks!
RE: Flex_CT uses
I was also pondering my earlier statement wrt placement of the CT, on a non-shielded portion of the cable (ie between the stress-cone and the lug). I believe that you can install the CT on any shielded or non-shielded portion of the cable. I recall that we routinely install a zero-sequence CT (ZSCT) around the shielded portion of a 3-conductor MV TECK-type cable assembly. This ZSCT can pick up ground-faults currents of 1 ampere. Note, in this case the shield drain wires are passed back through the ZSCT.
Comments anyone?
GG
"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)
RE: Flex_CT uses
Regards,
RE: Flex_CT uses
RE: Flex_CT uses
RE: Flex_CT uses
RE: Flex_CT uses
RE: Flex_CT uses
RE: Flex_CT uses