UPS for MV equipment auxiliaries - "Redundant" vs. "Dedicated" 1

[Delta40]

My specs call for redundant UPS backup for MV equipment auxiliaries. The Contractor has provided a redundant UPS for MV equipment auxiliaries but has also connected emergency lighting to the UPS. The Client's engineers say this should be a "dedicated" UPS and have no other systems, such as emergency lighting, connected as the other systems will shorten the backup time for the MV auxiliaries. This is, of course, correct but is the Contractor compliant with the specifications (which did not use the word "dedicated")? Or could one argue that in spite of the specs failure to require "dedicated" UPS backup, good engineering practice would require the redundant UPS supplies to be dedicated for MV equipment auxiliaries only as this is critical equipment?

 

[VEBill]

"...shorten the backup time for the MV auxiliaries..."

Does the specification (or applicable regulations) mandate a minimum time period that the UPS shall provide power? Does the contractor's solution meet that requirement, even though it's also powering the lights?

(This isn't my area, but I figured I'll kick things off with the obvious question.)

 

[zeusfaber]

Do your specs say how long the UPS has to support the MV Auxys for?

With the emergency lighting connected as well, does the UPS still last as long as specified?

If so, the client seems to be trying to get more supported time than they've paid for.

A.

 

[zeusfaber]

(The last two posts, typed simultaneously, tell you something about the way the Military does spec writing)

 

[sibeen]

My first question would be, what is a redundant UPS? One that is not necessary?

If the specification did not mention that the UPS was to be dedicated, and if the UPS fulfills the required battery autonomy time, then the contractor is quite within his rights to provide the UPS as is.

Contractors are not mind readers. They either do, or do not, comply with a specification. If the client and consulting engineers have screwed the pooch, why should a contractor be to blame? If a change is required I would expect the contractor to put in a claim for a variation, and be paid for such.

 

[LionelHutz]

It sounds like the contractor met the spec. You'll have to pay to fix it if you don't like it.

 

[ScottyUK]

Sounds like the spec might have a few additional problems to look at. No UPS is as reliable as a flooded cell battery. Next time run the auxiliaries on 110V DC and avoid the complication and reliability problems of a UPS.

 

[Delta40]

OK; great responses from everyone! Thanks! To answer some of the questions raised above, the battery (time) autonomy is 30 minutes. All UPS systems on three substations were successfully tested and witnessed by the Client (even with a larger load of 2kw and only about 55% battery charge at the start of the tests). So, even with emergency lighting, wall sockets and servers backed up by the UPS, all UPS systems passed the autonomy test.

Yes; redundancy is defined as "unnecessary" but a UPS is only unnecessary while prime power is being supplied. I believe my Client has defined "redundant" as "additional" and this is in error. The Contractor has now provided three additional, dedicated UPS's to meet the Client's demands and has submitted a Variation request.

 

[dpc]

Late to the party, but "redundant" in this context (in the United States) means backup or spare. This usage is extremely common so I'm a little surprised at the confusion, unless it is a case of the Contractor going into his "dumba$$" mode for financial reasons.

In any event, a simple one-line or block diagram of the desired system is usually a good idea.

 

[Delta40]

Per McGraw-Hill Second Edition Dictionary of Engineering:

duplexed system [ENG] A system with two distinct and separate sets of facilities, each of which is capable of assuming the system function while the other assumes a standby status. Also known as redundant system.