Transfomer tap changer vs voltage regulator
Transfomer tap changer vs voltage regulator
(OP)
When utility engineers have the option, do they choose between an on board tap changer or individual voltage regulators in the feeder bays? What are the pros and cons to either?






RE: Transfomer tap changer vs voltage regulator
A key advantage to using separate sets of voltage regulators is that you can regulate the voltage for each feeder rather than making a compromise setting for the 2 or 3 feeders if you had bus regulation.
In addition, voltage regulators are more limited in their short circuit handling capability compared to LTC. For a large MVA transformer, you might be able to use only LTC. For smaller ratings, LTC and regulators can be used. You can check the standards on this.
RE: Transfomer tap changer vs voltage regulator
Would you happen to know to what degree individual feeder regulators have fault current limitations?
RE: Transfomer tap changer vs voltage regulator
I think the standards require a minimum fault rating of 25 times the base load current raring of the regulator. Don't have the standard in front of me, so you probably need to check.
Alan
RE: Transfomer tap changer vs voltage regulator
The only disadvantage that comes to mind is each feeder will have reduced contingency capacity, but that may not be an issue on high performing circuits.
In regards to the regulator configuration, if a closed delta system is employed the regulators must be slaved, buck/boosting in synchronism where as wye connected regulators may be advance at any position regardless of the other two?
RE: Transfomer tap changer vs voltage regulator
RE: Transfomer tap changer vs voltage regulator
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RE: Transfomer tap changer vs voltage regulator
If you are talking about the power generator voltage regulator and the unit transformer with OLTC, probably, AVR shall be used for the fast response and for the finer voltage regulation. For the coarse regulation, OLTC may be used. But the priority is for the generator AVR to operate.
RE: Transfomer tap changer vs voltage regulator
RE: Transfomer tap changer vs voltage regulator
In cases like this what is the typical loading per feeder bay?
RE: Transfomer tap changer vs voltage regulator
RE: Transfomer tap changer vs voltage regulator
RE: Transfomer tap changer vs voltage regulator
RE: Transfomer tap changer vs voltage regulator
RE: Transfomer tap changer vs voltage regulator
LTCs in main power transformers are notorious to be prone to fail do to the moving part technology used in most units.
Although more expensive and larger space taking, some utilities prefer regulate the individual feeder with 3-single phase voltage regulator transformers(VRT). In case one VRT fail, it is easy to replace it and even operate the feeder by-passing the VRT in many instances.
Many distribution substations use automatic mechanical switching cap banks for additional voltage regulation during heavy load conditions.
In high density populated area in the East Coast, one of the oldest utility use feeder voltage regulators in a 4 kV switchgear with dedicated bay in the SWGR line up for 3-single phase VRT bank.