Joined: 17 April 2002
I'm responsible for the electrical designs on a developing energy from waste plant and we have recently lost power due to damage in the DNO network. The site is supplied at 33kV and it is transformed twice to 11kV then 400V for the services and controls.
Since power was restored (no thanks to the squirrels who were harmed in causing the fault in the first place), we have had some component failures, so I had the voltage level retested today to find it was 270V single phase.
A check of the other voltages showed that the 11kV was high and the 33kV arriving on site was at 35kV.
We managed to set the LV transformer tapping down, but the DNO admitted that there was a problem on their network and tonight they resolved it.
I'm now concerned that the overvoltage may have stressed components in some of the electronic boards of various equipment connected: VSDs, instrumentation, DC power supplies, UPS, PLCs etc. Some of these will continue to work, and some may have an overvoltage cutout, although I've not seen any evidence of equipment powering itself down.
Does anyone have any suggestion of a methodical way to determine whether any of the electronic kit may be liable to premature failure?