Acog
Line impeadance can be gained by conductor data, zo or k factor is more tricky as multiple return paths are usually possible (ground and return conductor). Omicron supply equipment to take on site accurate measurements CPC100 + CPCU1...
acog
I have never attempted to perform the test you propose based on risk of personal injury, I have tested isolated cable sections using series resonance as mentioned earlier. I also have a 132kV circuit to commission shortly and plan for a lineworker to visit each support and varify (sign)...
Acog
Be very careful with induced voltages they can and do KILL, your megger probably wont like then either. I would test all cable sections either with vlf or series resonance at the appropliate voltage to satisfy your cop's and visually inspect overhead line sections. If your protection is...
Hi
The lack of a ground hasnt caused your mal op but is a safety issue, check for the ground connection in the relay panel it may be there, but as you correctly say multiple grounds are an issue. Does the scheme have ct supervision and check zone / frame leakage, if no supervision scheme is...
At transfer tap positions a contact usually cam operated is made to hold in either the raise or lower contactor causing the tap changer to run on through the transfer tap. Find the contact on your schematic drawing and trace through the wiring checking the contact makes in either direction.
I dont think that I would consider going down this method of supply, all sounds far too risky. What would happen to the engineer responsible if a line came down and remained live due to poor earthing / inadiquate protection with a high possibility of injuring someone or worse, I know what would...
Forgot to mention zone 1 set to 0s with Zone 2 & 3 set to 400ms / 800ms respectively, all zones have the same distance setting, therefore zones 2 & 3 act as backup hitting the trip relay from different output relays within the distance relay.
We have many sites supplied in this way with the lower voltage side tied. The trick is to set the distance relay to look into the transformer and not beyond. Transformer diff, OC, BEF & REF will look after your TX via local and remote end intertripping with DOC as backup should the intertripping...
Slavag is correct.
Use the higher ct resistance to calc you relay setting allowing 16*flc, your relay setting """MUST""" be less than half your ct knee point value. All ct's must have the same characteristics (class X).If resistance grounding is used calc the stablising resistor to allow...
Have you calculated phase-phase & phase-earth impeadances, the difference between 80% & 100% I think would be marginal, could the tolerence on your distance relay take you past you 100% figure and into other protected zones with the possibility of coordination issues.
Distance is primary protection whilst 50/51 & 50N/51N used as backup. I would be very suprised if you could achieve an accurate 80% zone 1 setting based on a 1km length of ug cable though, this type of protection is better suited to transmission lines.
Conductor sag will be different between the two types of conductor. There is an increased risk of the ACSR corroding with the copper conductor supported above it.
Hello linkect
By carrying out your proposal you increase the risck of CT saturation and REF operation for through fault conditions, cheapest solution is to replace your OC relay.
Thanks David for your speedy reply.
Indeed P1 & P2 in both CT's are of the same polarity, CT ratios are the same.
I will give your comments some thought in terms of phase angle relative to "a" phase.
Hi
I have encountered a curious CT connection and need some assistance.
(1)2 CT's one in "a" phase the other in "b" phase.
(2)s1 of the "a" phase CT is connected to s2 of the "b" phase CT.
(3) s2 of the "a" phase CT is connected to s1 of the "b" phase CT
The combined output is used in a OLTC...
It depends, is the sf6 their for arc extinction or just to increase the bil rating of the swgr. Some low pressure sf6 swgr have vacuum interupters and then surrounded with sf6 to increase bil rating.
