thanks for the discussion guys; I'm telling you, I'm getting a variety of opinions on this, including some technical/sales folks "on the phone with their technical support group" who are telling me these O/L's physically break the circuit. I'm of the opinion and in agreement with waross; some...
try this,, had to upload the PDF to a Google Drive account. I couldn't seem to upload multiple image files in a single post.
https://drive.google.com/file/d/1ljZZgbsONowc0bFFdvp-7UP3sxlviVqf/view?usp=sharing
Thanks for the discussion, see if the upload works, should be a PDF with schematics and photos of the actual O/L's in question.
https://files.engineering.com/getfile.aspx?folder=de39642b-71b2-4b5a-9f0f-a251ff15947a&file=DC_Lube_Oil_Pump_Schematics_&_OL_Relays.pdf
Folks,
We're having to review Emergency DC Lube Oil Pump circuits to ensure the O/L's do not trip the motor. My schematic shows we do have O/L Relays in the circuits, but their Auxiliary contacts are only used for alarming purposes, they're not used to drop out the Main Contactor/Starter...
thanks for discussion so far..
I've realized that i'm not applying the correct formula here. The only reason I've been asked to specify the Line Characteristic Z is because its on the manufacturer’s order form. And I don't really know if it needs to be exact or approximate,,,,just because I...
Folks,
I'm working on a project which is my first on a DCB scheme using Power Line Carrier equipment. We are replacing the relays, TX/RX unit, and the line tuner, but will be using the existing line trap,, and I have little information on the line trap. I do know from old records that its a GE...
UPDATE: We have found that the PVD relay was not the cause of trouble at all. Turns out, the relay never targeted or issued a trip. Initial indications from our CC classified the operation as a bus differential, but that just wasn't the case. Turns out, a cap bank relay on the same bus...
Thanks for the discussion so far. To answer a few of the questions:
1. The relay is a 12PVD11C11A with the 87L unit at 180 Volts, the 87H unit at 2 amps. I hope that answers the current supervision question, again just unfamiliar with the scheme and we don't have alot of documentation since...
We had a PVD High Impedance Bus Diff relay misop for an out of zone LG fault. Quite frankly, I'm not that knowledgeable about High Z style relaying schemes. This was installed years ago and we now use percentage current diff's on most all 87B schemes now. And of course its electromech and we...
Folks,
Got a situation that I believe is a first for our utility. On a segment of our 115kV system, we have a few long radial feeds serving distribution (115-13.2 kV) loads. Planning Dept wants 15MVAR banks installed on the far end of these radial for system voltage support. In these cases...
By "overlooked or forgotten" I mean those who came investigating why there was "miscoordination" between the line breaker and the tiebreaker. Initial thought was the linebreaker miscoordinated with the tiebreaker for a through-fault on the transformer.
thanks for the reccomendations!
Recently had a tibreaker operation on a YDY transformer due to a SLG fault on the transmission line feeding this sub (the "Y"s are grounded, feeding radial load). The upstream line breaker and the local tiebreaker at the YDY primary both operated as expected. I know the primary grounded wye is...
We've had concerns about using digital relays with 50 (instantaneous) elements on the high side of power transformers (for instance, 115-25 kV 12/16/20 MVA). We set this element to clear trouble on the high side inst, to avoid miscoordination with upline transmission breakers. And yes, we use...
Thanks again for informing me and keeping this discussion going. I've got my sine generator and I want a phase (time delayed essentially...??) lagged version of that same wave, at the same frequency. I've settled on 180 deg of phase shift as the max, but yes, I do want to have manual control...
