High Voltage Relays

• Feb 19, 2015

• #2

Skogsgurra

Electrical

Mar 31, 2003

11,815

SE

This is too much!

Are you kidding?

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

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• Feb 19, 2015

• Thread starter
• #3

recalli349

Electrical

Feb 12, 2015

7

CA

Haha, definitely not kidding. What exactly do you mean by too much? I wanted to be as specific as possible.

 

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• Feb 19, 2015

• #4

crshears

Electrical

Mar 23, 2013

1,899

CA

Hey there recalli349,

What kind of circuit is this?

Are you asking about what type of switching device to use to ensure that the 4.8 kV potential is never applied to the 600VAC multiplexer? If in fact that is your question, it is your use of the word "relay" that is throwing us off.

I don't profess to have a great deal of the type of experience applicable to your question, but I have only ever seen that high a potential switched using either a circuit breaker or fuse-equipped cut-out switch. As near as I can tell, what you'd want to have is a ganged disconnect switch interposed between the transformer winding to be hi-potted and the multiplexer, the operating mechanism of which incorporates a 'b'-type position or limit switch wired in such a way that the 4.8 kV supply cannot be applied to the unit under test unless the interposing switch contacts are open.

Hope this helps.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

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• Feb 19, 2015

• #5

ScottyUK

Electrical

May 21, 2003

12,915

DE

I would suggest using a switch in each pole as a disconnector, and a second switch driven in anti-phase applying a circuit earth to each pole on the 600V side of the system. That way there is a much reduced possibility of HV finding its way to the LV side due to capacitive coupling or leakage.

Gigavac have some multi-pole HV relays which look like a plausible solution to integrate all four switching devices in one package.

 

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• Feb 19, 2015

• #6

Skogsgurra

Electrical

Mar 31, 2003

11,815

SE

By kidding, I mean that your diagram seems to show 4800 V being connected to the 600 V mux when the rightmost contact closes.

That is definitely too much - in several senses.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

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• Feb 19, 2015

• #7

zappedagain

Electrical

Jul 19, 2005

1,074

US

You want a 600V relay that is designed to pass a 4800V hi-pot test.

Z

 

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• Feb 19, 2015

• Moderator
• #8

waross

Electrical

Jan 7, 2006

28,794

CA

Scary on several perspectives.

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

 

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• Feb 20, 2015

• #9

ScottyUK

Electrical

May 21, 2003

12,915

DE

You want a 600V relay that is designed to pass a 4800V hi-pot test.

Click to expand...

Untrue. You want a relay that is designed for 4.8kV service voltage. A hipot test is a one-off or very infrequent withstand test, not a routine operating condition. You're using the component at 4.8kV in a routine operating state. A 600V relay will not have adequate clearance or creepage distances for service at 4.8kV.

 

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• Feb 20, 2015

• Thread starter
• #10

recalli349

Electrical

Feb 12, 2015

7

CA

Thank you for the responses everyone. The relays would only close once the hi-pot has been turned off. The relays will never pass 4800VAC. I am just wondering if 4800VAC is applied to those two relays (when open), what would the requirements of the relays have to be to ensure that breakdown does not occur. I am not an expert nor an intermediate in this field. If there is something alternative to a relay that would work better, then I will research into that.
ScottyUK, these Gigavac devices look great. Thanks!

 

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