Sorry for not checking back sooner, been on the road lately and my thoughts have been elsewhere . . .
waross - Yeah, I had come across that Eaton UPS paper previously. Read through it more closely and didn't see the applicability to my question, kind of just mentioned briefly the need to...
Hi all,
Probably a stupid question, but . . .
I'm spec'ing out a 480V MCC lineup to replace an existing one that is at end-of-life. Getting a Rockwell Centerline MCC with all the bells and whistles, E300 overloads etc. Going thru the approval dwgs now.
3000A Main CB has an LSIG trip unit...
Hi,
Had a question about contact ratings related to a simple circuit . . .
In a new substation being built I have a SEL-2506 I/O module with 125Vdc inputs for wiring in miscellaneous building alarm contacts (125Vdc battery charger alarm, HVAC alarm, etc). Additionally, an H2 detector is being...
Thank you for the responses. I am glad that you concur that this "momentary" current draw shouldn't really be used to rule out relays with lesser continuous amp ratings, that was pretty much my take as well. And I had been keeping the thought of using an old beefy relay like the MG-6 in the...
Hi all,
I am designing a project and am coming across some frustration dealing with interposing relay contact ratings. Any help would be appreciated.
Problem 1. I have a 4kv switchgear breaker I am replacing the relaying on. Due to some design considerations, I need to use interposing...
All,
I was wondering if anyone knew / understood why IEEE1547 is so specific about requiring phase-to-phase voltage detection for 27/59/81 tripping? (It of course gives the caveat that phase-to-neutral voltage can be used if the utility and DG are connected by a wye-wye grounded or single...
Are there any good relay guys out there that can give me some comments on the following.
At one of our facilities, we have a large cross compound unit connected generator, HP and LP approx 300MW / 20kV each. It is high impedance grounded with the neutral transformer with secondary resistor...
Cranky,
I don't disagree with any of your comments, but I'm just trying to figure out the settings that are already there. I think that this is a very unique application. This is being used as part of an out of step (OOS) protection scheme on a generator, it will trip the unit if supervision...
davidbeach,
If you are asking if the relay actually performs correctly, yes it does. From the last cal, at the settings mentioned above, the relay tested at ~12.38ohm with ~90deg MTA. I should have put that in my original post.
I know that these settings are proper. I am interested in how a...
Hello,
Are there any good relay guys out there that can help me out with the following? I am trying to figure out how tap settings are determined for a KD-10 relay at a MTA other than nameplate. I know how to come up with settings at nameplete MTA using the formula ST/(1+-M).
So for a KD-10...
Thanks to all of you for your input.
The switchgear involved in this particular failure was ITE HV. The breaker was a 1200A.
DPC:
When you said that two starts/day is probably an application for a starter and not a breaker per the specs, what are the specs that you are referring to...
Can anyone give me some guidance or point me to some technical papers regarding the use of medium voltage breakers vs starters based on starts/stops a day?
All of my company's power plants were built in the 1950s and 1960s and were originally baseload. All 4kV motors were supplied from...
The reason a larger gauge wire (#10) than is needed for 5amps is used is to reduce the burden seen by the CT secondaries. Larger diameter wire has less resistance. Combine the resistance of the wiring with the burden of the connected relay or metering coils (available in manuals) to get total...
The plant I work at has recently had some issues with battery grounds (equipment misops, false indications, etc). We are fairly effective at locating and removing them but usually we don't notice them until a problem has occurred. Aside from increasing operator surveillance of battery grounds...
