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Topic Title: Under voltage release
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Created On: 05 February 2013 10:47 PM
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 05 February 2013 10:47 PM
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Martynduerden

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Is under voltage release a requirement on dist boards feeding it equipment ?

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Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 05 February 2013 11:41 PM
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gkenyon

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Originally posted by: Martynduerden

Is under voltage release a requirement on dist boards feeding it equipment ?
"it" = "Information Technology" or "Isolated from Earth"?

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Eur Ing Graham Kenyon CEng MIET TechIOSH
 06 February 2013 12:40 AM
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Martynduerden

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Originally posted by: gkenyon

Originally posted by: Martynduerden

Is under voltage release a requirement on dist boards feeding it equipment ?
"it" = "Information Technology" or "Isolated from Earth"?


"it" = "Information Technology... Sorry

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Regards

Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 06 February 2013 09:53 AM
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AJJewsbury

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Is under voltage release a requirement on dist boards feeding it equipment ?

Not normally, but I suppose it could be a customer requirement.

Normally voltage regulation is a job for the UPS, not the DB. A lot of common UPSs are capable of voltage "boost" (or trim) - effectively auto changing a tap on a transformer - so continuing to use mains rather than using up battery power - so if the DB is upstream of such a UPS, it could be preferable to let low voltages through.

- Andy.
 06 February 2013 10:01 AM
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OMS

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You need to assess the impact of undervoltage creating harmul effects on other equipment. other services or on the supply - 331.1

You then need to assess if a reduction of voltage could cause danger - and if you are satisfied no danger exists but you need to protect the equipment from damage you need to consult with the relevant person what is suitable - 445 et seq.

If you decide to do it, refer back to 445 et seq as advised bt 535.

In the vast majority of cases the answer is no, you don't need undervoltage release. I've seen some truly catastrophic losses caused by people deciding that the comms room needs and e stop and arranging that via a contactor rather than a trip circuit wired via the protecticve circuit breaker. No one notices the problem, until a brown out drops out the contactor and the whole lot goes down the tubes.

If this relates to that busbar job you mentioned in another thread, then most certainly, you wouldn't want undervoltage release. You may just consider both undervoltage and over voltage protection at the desk power bars (usually specified in conjunction with delayed re starting).

You may get undervoltage protection by default if you operate via line interactive UPS - at the end of the battery autonomy, the invertor will shut down when it can no longer maintain specified output parameters.

You would almost certainly not want the type of coarse undervoltage protection associated with contactors or shunt trips at a dist board level.

What does the brief say ? -

Regards

OMS

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Failure is always an option
 06 February 2013 09:22 PM
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Martynduerden

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Originally posted by: OMS

If this relates to that busbar job you mentioned in another thread


Not related but similar.



What does the brief say ? -


Your smiley is far to appropriate! I'm sure I could just supply a expresso machine with the spec I have!

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Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 07 February 2013 09:35 AM
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OMS

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Your smiley is far to appropriate! I'm sure I could just supply a expresso machine with the spec I have!


LoL - OK, one of those jobs then

I guess the starting point is what are you trying to protect from what - be that a danger, an inconvenience or a total loss of capability or service.

Regards

OMS

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Failure is always an option
 07 February 2013 10:43 AM
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AJJewsbury

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I guess the starting point is what are you trying to protect from what

or your wallet from a customer who thinks lots of extras should be done for free as he thinks they're "in the regs" or "standard practice"?
- Andy.
 07 February 2013 12:20 PM
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OMS

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Originally posted by: AJJewsbury

I guess the starting point is what are you trying to protect from what


or your wallet from a customer who thinks lots of extras should be done for free as he thinks they're "in the regs" or "standard practice"?

- Andy.


Which is why you need a design brief, or an appointment to develop that brief, with the relevant adjustment for output design deliverables defined in the fee offer - and if D&B, the cost to reflect the developed design solution -

What you exclude, is often more important than what you include, in any offer

Regards

OMS

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Failure is always an option
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