Thank you both. You have confirmed my suspicion.
To discuss a little bit more, does anyone know if there is a NEMA (or other) specification that indicates the short term (like, say, 1 minute) rating for these type of contacts? All I see in NEMA is make/break and continuous. I noticed the...
We have purchased a Siemens SPS2 46kV breaker. We have a 125VDC trip circuit. Siemens lists the trip circuit draws 12A(Nom.) at 70-140VDC (125VDC Nom.). They Use a Square-D pushbutton (Class 9001 Type K-30 mm with type KA1 contact blocks) in their trip circuit to energize the trip solenoid in...
I received the following response on my original three questions (beginning of this thread)from a transformer vendor and thought I'd share them:
1. The 55/65 designation has been removed from ANSI Standards, but is still available from manufacturers.
Note: Reference IEEE Standard...
Thank you tulum. My understanding, though, is that by purchasing a higher temperature rise transformer, you are simply buying a lesser weight transformer. Let me explain:
Per IEEE Std. 1276-1997, by increasing the nameplate temperature rise (initially from 55C to 65C and later for specialty...
Thanks to all of you for your input. Regarding the 55 degree comments, my understanding is that the 65 degree insulation is an upgraded insulation. I thought ANSI rated a 55 deg C xfmr maximum continuous kVA based on the same 30 deg C avg, 40 deg C max peak 24h, rating as the 65 deg insulation...
Is it more expensive if I keep the top ratin the same? For example, If I buy a 65 deg C xfmr that is 20MVA, isn't it the sme thing as if I bought a 17.85 / 20 MVA, OA, 55/65 deg. C xfmr? Sorry, I made a mistake in my calculation of the 55 rating in my original post item 1, it should have been...
Historically, we have specified power xfmrs that are 55/65 Deg C rated (for U.S. use). My understanding is that this was an older designation used when the insulation was originally transistioned from the older 55 Deg C rating to the newer 65 Deg C rating. My questions are as follows:
1. It...
