Pump station Electical Problems
Pump station Electical Problems
(OP)
Hello all,
I work for The town of Paxton, Light Dept. We have a problem at a water pumping station that I,m having trouble with. We have one circuit in town, 13,800 volts grounded wye. The pump station has a 45kVA 3 phase pad transformer with a delta 240/120 secondary (Xo bushing is provided for 120 volt load in pump building, ie lights, scada, teleometry, comm. radios.)
Problem: Water dept. is consistently burning up variable speed drives, boards inside of scada control box, radios, isolation xfers. It seems like, when the town has a dip in power due to a fault/recloser operation, that these problems arise.
Could this occasional loss of power and/or delta secondary configuration with a wild leg be causing a surge when re-energized?
I will provide any needed info to help diagnose the problem.
Thankyou
Chris
I work for The town of Paxton, Light Dept. We have a problem at a water pumping station that I,m having trouble with. We have one circuit in town, 13,800 volts grounded wye. The pump station has a 45kVA 3 phase pad transformer with a delta 240/120 secondary (Xo bushing is provided for 120 volt load in pump building, ie lights, scada, teleometry, comm. radios.)
Problem: Water dept. is consistently burning up variable speed drives, boards inside of scada control box, radios, isolation xfers. It seems like, when the town has a dip in power due to a fault/recloser operation, that these problems arise.
Could this occasional loss of power and/or delta secondary configuration with a wild leg be causing a surge when re-energized?
I will provide any needed info to help diagnose the problem.
Thankyou
Chris





RE: Pump station Electical Problems
Is the site distribution transformer’s "X0" bushing solidly grounded? Is anything besides 3ø motors served from the high leg? Can you detail the primary configuration? [id est, locally grounded, and to what in detail? 4-wire from the 13.8kV distribution circuit? multigrounded or unigrounded?]
RE: Pump station Electical Problems
Do the failures all seem consistent with a voltage surge or high voltage condition?
You might also consider installation of secondary side surge suppression at the service entrance.
RE: Pump station Electical Problems
RE: Pump station Electical Problems
RE: Pump station Electical Problems
As far as the frequency, problems seem to arise most often after the primary circuit has a operation (2 second outage), due to a fault. I'm curious if there is some kind of inrush, or transiant being created during re-energization.
The primary feeding this pad is 13,800 volts grounded Y. Looking at the pads name plate, the internal primary coils are wired wye with all the H2's connected and floating. Through my research, this is correct, as grounding the H2's could lead to a whole host of problems, leading to roastout of the pad. There is no load off the wild leg, other than three phase load. The only equipment being damaged is the single phase load.
RE: Pump station Electical Problems
IEEE Standard C62.92.4-1991 states, “…an open conductor in a three-wire primary results in a single-phase input and output of the bank.” It is conceivable that high-side faults and single-pole reclosers could exacerbate the situation through significantly unbalanced secondary voltages.
Although not a trivial solution, C57.105 suggests as an alternative to highside wye-point solid grounding, that a resistor may be applied to limit resonant conditions in the bank. An electrical-engineering consultant should be contacted for review and recommendations.
[Mapquest shows six states with “Paxton” in the US.]
RE: Pump station Electical Problems
RE: Pump station Electical Problems
RE: Pump station Electical Problems
RE: Pump station Electical Problems
If all else fails, you might want to consider replacing this transformer with one that has an electrostatic shield.