VT's off MSP....
VT's off MSP....
(OP)
In a new residence being planned, we'll have a:
"MSP Meter/Main Service Panel 200A 277/480V 3PH 4W"
that will feed a 200A 3ph/4W transfer switch; choosing between the grid above and a backup source. We have no need for any loads on the PG&E side of the transfer switch, save one: VT's & a loss-of-phase detector.
The licensed electrician has indicated 200A 480V MSPs are not available with distribution, so a panelboard will have to be added between the MSP and ATS 1.
...just to tap off a few VA for the VT's.
My question is: is there an alternative? A 3-fuse fuseholder or such that's approved for this kind of application? I was thinking such would be connected with ~18G Teflon wire, so that worst case, you get a suddenly-hollow piece of Teflon tubing, and copper vapor deposited on the MSP's walls. [Been there, seen that....]






RE: VT's off MSP....
Another option may be to install the VTs in the ATS cabinet.
Another option may be to use a bus gutter or splitter and tap off to a single breaker for the PTs.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: VT's off MSP....
It has what you need to do. You may or may not like it but if you don't follow their standards they won't hook up your service.
The Greenbook is a good reference for any future projects, Suppliers know what to sell you and contractors know what to install if you follow the PG&E standards.
RE: VT's off MSP....
Per 5.2.1 we provide a socket, etc.
But to be more explicit; I am not talking about VT's used for official metering/billing. [PG&E has not yet decided if we get a integral meter or external CT one; I'm told.]
My focus is I need separate monitoring on our side of the meter.
My question is {restated}:
Are there small fuseholders/breakers that are approved/acceptable for sampling a few VA's of 480 without a big panelboard?
I can put them in the ATS cabinet.
btw: Are the terms PT & VT now considered interchangeable? I recall "PT" was always used in my school daze, but VT seems to be common now.
RE: VT's off MSP....
Of course, that's no problem. Look inside any 480 V motor starter and you'll likely find 480 V fuses for the control power transformer.
The problem is getting the line side connected in a safe manner and how they will be accessed.
David Castor
www.cvoes.com
RE: VT's off MSP....
Thanks. I'm thinking something one like of those tiny 48O starters I've seen, in the less than 1A size. They mount on DIN rail and have start-stop buttons. I've not seen a smaller 3ph 480 switch. A fuseholder could follow if required. (The one in hand is a Telemacanqiue GV2 series. <http://
RE: VT's off MSP....
RE: VT's off MSP....
RE: VT's off MSP....
You might consider something like bulletin 129 class J fusible switches at www.boltswitch.com/pdf/129.pdf
RE: VT's off MSP....
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: VT's off MSP....
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: VT's off MSP....
http://w
Alan
"The engineer's first problem in any design situation is to discover what the problem really is." Unk.
RE: VT's off MSP....
As for a fuse older or circuit breaker box have on made. Draw it up and get a UL panel panel shop to build it. It will be listed and the inspector will accept it.
RE: VT's off MSP....
As for a simplified SLD:
{from BU power}
\--[fuse]-VT----
\
PG&E--(M)--[200A breaker]-------------[ATS]-----------
|
|
\--[fuse]---VT-----------
RE: VT's off MSP....
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: VT's off MSP....
{from BU power}
\--[fuse]-VT {BU V mon.}
\
[ATS]-----------load
PG&E--(M)--[200A breaker]--------------/
|
|
\--[fuse]---VT-------{grid V mon.}
The monitors are both voltmeters and phase loss/reversal monitors.
RE: VT's off MSP....
If you want acronym confusion, I recommend a tour at NASA; the directory of acronyms used on the Shuttle is a big book; and while the book has a title, everyone uses the title's acronym.