voltage spikes?

[tvg]

i work at a hospital and we have had an unusal amount of electricial equipment going out as of late, microwaves,heating elements,frezzers,ect. On my 120v system i have had readings of 127 to 129. On my 208v i have had readings of 220v. could this be a voltage problem?

 

[hurk27]

Depending upon what type of meter you are using to mesure this with, 129 volts is high, but not to the point it should be causing this amount of failure, since your 208 is also high, this has to be a problem with the transformer or ahead of it.

I would expect a hospital to be fed with a 480/277 system, then have many 480-208/120v transformers for local loads, if so you need to see what the 480 voltage is, if its high also then the POCO needs to be brought into the problem, if the POCO supplys the 208/120 then same thing, otherwise the hospital owns the transformers, and someone is going to need to trouble shoot where the hi voltage starts.

High voltage on the secondary is only caused by a few things:

Shorted primary turns.
Too low primary tap setting.
If Y supply, lost Y neutral with transformer fed line to neutral. (single phase)
Higher then normal primary voltage.

 

[robbietan]

i work at a hospital and we have had an unusal amount of electricial equipment going out as of late, microwaves,heating elements,frezzers,ect. On my 120v system i have had readings of 127 to 129. On my 208v i have had readings of 220v. could this be a voltage problem?

utilities have a plus/minus 10% bandwidth for their voltage. if you have a 120V nominal supply, a reading of 129V is high, but still within the plus 10% voltage limit of the utility. same is true with your 208V supply, the limit for that is 228V, a reading of 220V could still be considered "normal".

I could suggest that you monitor transients instead.