480 V sensing required

[xnuke]

A source typically connected to a 480 V bus requires 480 V sensing from the 480 V line side of the main breaker for grid synchronization purposes. For a proposed application however, the source will be connected via a step-up transformer to connect to a 13.2 kV bus with a 13.2 kV line feeding the main breaker. Normal 120 V secondary sensing from a 13.2 kV:120 V VT is not an option; the source vendor still requires sensing at 480 V. Are either of these viable options for this one-off project:
[ol 1]
[li]Get custom VTs made with 480 V secondaries[/li]
[li]Use standard 13.2 kV:120 V VTs with 120 V secondaries, then connect 480:120 V VTs backwards to the normal secondaries in a step-up fashion to provide the 480 V[/li]
[/ol]

Please describe advantages and disadvantages for either, or provide other viable options. Whatever the solution, it has to fit into the MV switchgear.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[jfpe]

Can you sense on the low side of the transformer and use 480:480 PTs?

https://www.galco.com/buy/Instrument-Transformer-Div-of-GE/3VTL460-480-480

-JFPE

 

[xnuke]

Thanks for the idea, but the supplier of the source requires sensing from the medium voltage breaker's line side.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[davidbeach]

Can you get 6.6 or 6.9kV to 120V VTs with a 15kV continuous overvoltage rating?

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[xnuke]

Interesting idea, David; I'll run it by our factory engineer.

What did you think of the second option I gave in the OP?

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[davidbeach]

Extra parts and pieces, but maybe what it takes. The whole "must be 480V" seems hokey, most equipment these days should be far more flexible.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[FreddyNurk]

What davidbeach said, particularly about the 'most equipment' aspect. Note that you'll likely end up with someone noticing the voltage range every so often and raising a defect.
Admittedly I don't work with US voltage stuff, but most of the synch equipment I've seen either accepts 120V as VT secondary inputs, or at most accepts ~400V, and sometimes both with a software option to switch.

That said, is it the same source vendor that insists that the source supply at 13k2V and have 480V VTs? Seems to me that such equipment should be part of their scope of supply if that's the case. Any chance you can post a single line? I'm a little confused as to what is where from the description.

EDMS Australia