We’re currently commissioning a large substation with A and B systems from different manufacturers. The P&C design has done away with control switches, Lock out relays and replaced with virtual lockouts.
We’ve discovered that on the B system, the non volatile latches, used as 86 devices, are...
We see specifications for 10kV megger tests on oil filled equipment from time to time. We own several 1kV and 5kV units, but often have to rent a 10kV device. Examples of equipment may be HV VT's, CCVT's, Power Transformers, etc. Typical testing specs often also call out for a "Doble" or...
There is a closed thread, 238-349003, with a bit of discussion on Negative Power (and Watts) readings on an SF6 breaker.
We recently had a brand new 345kV Gas breaker flash over internally upon initial energization. The system was from the remote end and approximately 4 minutes after...
Generally speaking, I have seen 85CO switches on lines that have a communications based protection scheme.
Is there any general consensus on what exactly placing the 85CO switch in the "Test" position should do, especially to the protection
at the remote end?
My understanding would be that if...
I have been asked to investigate an issue for an industrial customer. There was an event where a 480V Main - Tie - Main Switchgear tripped both mains.
I performed a site visit today, gathered information. The 480V SWGR feeds motor loads only, a combination of VFD's and across the line motors...
I came across something that did not 'feel right' when reviewing a new installation. 138kV Utility switching station with several large generation sources tied into a ring bus.
There is an upgrade to the bus for new 87B (Bus Differential) relays. New panels, Lock Out Relay, Test Switches...
I was recently doing a Power Quality analysis at a small utility. Internally, when they run equipment (UPS in particular), there are some issues. In particular, it is when they run a certain generator (4160V 10MW - Wye Connected, Reactance grounded). The utility parallels with a much larger...
Story
Ignoring all of the technical details that will likely be wrong, 370 Million is a lot of people left in the dark.
Has there been a larger event in the world?
Let's assume we are talking about modern digital relays here. It seems in North America the Mho is preferred and in other countries the Quad is. My guesses would be historical preference or comfort.
I am aware that the Quad offers better resistive coverage.
My experience is that the Mho is...
Hi All-
I was reviewing some potential work and came across what I would call a convolution of security vs. dependability. Curious how others handle tripping. I am concerned about local tripping onlt.
Thanks
Can someone please explain to me why some designers continue to wire relay test switches "backwards"?
Example...
I am reviewing a DC schematic, where the +DC goes to the top (odd number ) of an FT type switch, then out the blade, then to the LOR contacts. This appears to only function as an...
I am curious about how folks in the utility world view this. We are a commissioning company and prefer to test for realistic scenarios. Our test protocol (on this job) calls for very simplistic tests.
I feel like we are forced to comply with test specifications that require light bulbs and a...
Greetings-
We have a customer that insists that all ratios of a MR CT be tested. We normally test all of the main taps, ie x1-x5, x2-x5,x3-x5,x4-x5. We are being asked to measure the inter tap ratios (x2-x3, x1-x2, etc). It is my understanding that the inter tap ratios are obtained via...
