Misapplied voltage potential damage

[ndimercurio]

Our head office recently experienced a 45 minute overvoltage when the local Utility (trying not to name names here) introduced 480/277V secondary when replacing pad-mount transformer to 208/120V wired building. I'm not a forensic engineer and may not find one in this forum, but as a licensed professional electrical engineer my company is asking for my advice. What types of things should I consider as possible points of damage other than the obvious equipment failures? Amazingly only a few copiers and fax machines were taken out and most PC's and other capital assets were seemingly okay. Do surge suppressors protect from this kind of overvoltage condition and are they compromised if so? Do I need to be concerned about building wiring integrity for potential future fires? Who/what type of entity should I get involved to check out the building systems other than insurance carrier?

 

[GoldDigger]

Our head office recently experienced a 45 minute overvoltage when the local Utility (trying not to name names here) introduced 480/277V secondary when replacing pad-mount transformer to 208/120V wired building. I'm not a forensic engineer and may not find one in this forum, but as a licensed professional electrical engineer my company is asking for my advice. What types of things should I consider as possible points of damage other than the obvious equipment failures? Amazingly only a few copiers and fax machines were taken out and most PC's and other capital assets were seemingly okay. Do surge suppressors protect from this kind of overvoltage condition and are they compromised if so? Do I need to be concerned about building wiring integrity for potential future fires? Who/what type of entity should I get involved to check out the building systems other than insurance carrier?

Surge suppressors cannot protect against a prolonged overvoltage, even if that overvoltage rises above their clamping threshold in the first place.
However they may conduct enough current before failing that they trip other overcurrent protection which will then protect attached devices from the applied voltage. That is not part of their design function, but can happen in some cases. And I would consider all of them potentially compromised. If they do not have an indicator that supposedly confirms that they are operating, they should be checked out for sure.

The power supplies in modern computing equipment are often designed for a wide range of supply voltages, and should in any case be able to protect the equipment they are powering even if they themselves fail.
Lighting ballasts, unless rated for multiple input voltages, may have been stressed to the point that there will be early failures down the road. Proximity sensors for lighting could be directly damaged.
Wiring will generally not be compromised since the insulation will be rated for 600V. The only potential damage would be from overcurrent during the high voltage condition, and I do not think you suffered from that.
Electric water heaters and other resistive heating elements which were operational during the outage may have their lives reduced because of hot spots in the resistive element which will eventually fail, and should probably be replaced.
Any devices powered by wall wart or brick external power supplies may have had those supplies compromised. Look for thermal damage indications at a minimum.
Those are just the ones that come to mind immediately. Hopefully one of the Forum members can give you a more specific recommendation on where to go from there.

 

[petersonra]

things that should have had 120V on them had 277V instead. in many cases it may not matter much as a lot of electronic products are designed to work at 120 or 240V and 277V is not far outside the range they can operate at.

motors won't like it nor will resistance type heaters like electric water heaters.

how much actual damage was done and what should be done as far as replacing things is hard to say.

at the very least similar things to those that already failed are good candidates for replacement.

surge suppressors do not protect from this kind of thing. in fact surge suppressors installed downstream of panel boards would probably have all failed, and in spectacular form.

personally, i suggest staying out of it if it is not something you know anything about. get some help from an actual professional with experience in dealing with this kind of problem.

 

[ndimercurio]

There were a few other entities that would not turn back ON and were immediately destroyed like Microwaves, Coffee Makers (this is an office building), etc. that we'll need to claim. It's the possible internally compromised components that may be lying in wait to prematurely fail down the road due to this event, that I'm wondering if there's a way to focus our attention on those types of items to get them checked out or consider their replacement if they are a hazard. We have some 48V CISCO phones, rack equipment, servers, isolation power transformers, inverters, and things on the LV data side that I wonder if there's a way to tell if they are prematurely compromised even though they seem to be working right now. Thanks for the response.

 

[mgookin]

I'd think a good starting point is to make an inventory of everything electric, starting where the power enters your facility. Put that in a spreadsheet with Y or N for damage potential. Someone's goign to have to estimate the decrease in useful life for things functioning now and then both sides are going to have to agree (all 3 sides?).