VT's off MSP.... 2

[fsck]

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....]

 

[waross]

I would install a metering cabinet and used fused VTs.
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

 

[BJC]

Google PG&E GreenBook.
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.

 

[fsck]

I've read both 05.pdf & 06.pdf in the Greenbook. The first issue is our residential 480v 3-ph is an exception they're granting us, so it's not in 06.pdf.

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.

 

[dpc]

Are there small fuseholders/breakers that are approved/acceptable for sampling a few VA's of 480 without a big panelboard?

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

http://www.cvoes.com

 

[fsck]

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.

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://www.usbreaker.com/images/product_images/CHT_NS.jpg>)

All this would mount inside the ATS cabinet.

 

[dpc]

I don't understand. You need a fuse, not a starter.

 

[fsck]

I'd like a disconnect. If they make non-starter ones in this size, we can get same. If they don't, it still is one.

 

[busbar]

You might consider something like bulletin 129 class J fusible switches at

http://www.boltswitch.com/pdf/129.pdf

 

[jraef]

There is an acronym semantics issue at work here. Some people are interpreting the MSP acronym as meaning Motor Starter Protector, a name given (by Siemens) to IEC style manual motor starters when used in North America. I think the OP was using the acronym MSP as referenced to Meter Service Provider, i.e. the power utility, municipality etc. that regulates the equipment configuration necessary for a legal hook up.


"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

 

[jraef]

Or Main Service Panel as well come to think about it. That's the problem with using acronyms, very imprecise.


"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

 

[alehman]

Most of the fuse manufacturers also make disconnecting type fuse holders. One example..

http://www.bussmann.com/pdf/3257c49f-909d-4602-a038-862d8829d956.pdf

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[BJC]

A one line wold help.
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.

 

[fsck]

Thanks for the boltswitch & bussman links. Do I correctly infer that a Class J fuse is called for in this case?

As for a simplified SLD:

{from BU power}
\--[fuse]-VT----
\
PG&E--(M)--[200A breaker]-------------[ATS]-----------
|
|
\--[fuse]---VT-----------

 

[waross]

Try using [ignore][tt] ahead of your one-line. The tt will give you mono-spaced text so that you can get your one-line to line up properly. I am assuming that the BU feed is supposed to point to the ATS. Don't forget to end with. [/tt][/ignore]

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[fsck]

[tt]
{from BU power}
\--[fuse]-VT {BU V mon.}
\
[ATS]-----------load
PG&E--(M)--[200A breaker]--------------/
|
|
\--[fuse]---VT-------{grid V mon.}

[/tt]

The monitors are both voltmeters and phase loss/reversal monitors.

 

[fsck]

BTW, the "MSP" acronym was the electrician's usage. I'd never heard it before, but when in Rome.....

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.