Recent content by scottf

If I'm reading your original post correctly, you should not have to provide external ferroresonance damping for CVTs. With VTs, one has to be concerned with system ferroresonance, therefore, an external damping strategy. With CVTs, there is a concern with internal ferroresonance, therefore...

If you're applying voltage to the CVT secondary, closing the potential ground switch (PGS) will short the intermediate transformer's primary winding and you will get high current in the transformer windings. To your original question, utility practice comes down to "is there 0% chance" versus...

There can be many causes and a lot more information would be needed just to hazard a guess.

Short answer: no One of the main problems is that you're mixing transient performance of a protection class CT with "steady-state" performance of a metering class CT. The accuracy of a metering class CT, is primarily a function of the % nominal current and the applied burden. All else held...

stevenal...the to neutral if connected line-to-neutral or to the other line if connected line-to-line. 2400/4160Y means the unit can be connected L-N on a 4160V system or l-l on a 2400V system.

Kiribanda- I don't believe you are correct You CAN use a 2400/4160Y V PT - which is a 2-bushing VT You CANNOT use a 2400/4160GY V PT - which is a 1-bushing VT The line-to-neutral voltage on an impedance grounded 4160V system is indeed 2400V.

1) The H2 bushing is rated to an insulation class and not a specific voltage. So the 5kV class would be 75kVp BIL and 26kV PFWV. 2) Yes, the VT can withstand temporary over-voltage. Normally marked as the Over-Voltage Factor (OVF) on the VT's nameplate. Typically, units of this design would...

The accuracy rating would be measured value.

My opinion is that type Rogowski coils would not be suitable for metering and certainly not revenue metering. The error defined for Rogowski coils is normally referring to the ratio error only. Phase angle error on Rogowski coils can be quite high...normally defined in degrees...0.5 to 1.0...

Do you have the previous page available? Would like to see what it says leading into the paragraph at the top of the page you posted.

I've never seen resistors placed in parallel with any kind of burden. The only thing I can think of is if the resistors are there in case the unit is energized with the relay isolated out of the circuit (Open test switch for example) and the resistors would be left to give the VT some load...

I have certainly seen oil-filled CTs fail catastrophically due to prolonged secondary open-circuit. I think your statement about the secondary voltage going up about 20 times the burden voltage is not correct...or not totally correct. For an rms standpoint, yes, but the peak voltages developed...

This question very much depends on the type of CT. LV, MV, or HV Bushing CT Dry-type MV Oil-filled HV Bottom line is that a CT left with an open secondary will fail in some manner given enough time. Often times, the initial failure will be at the secondary terminals, depending on the...

From what I've seen, there is no standard practice here and you'll need to refer to the unit's nameplate to see the CT relative orientation.

34500/34500 GRD Y is an odd-ball rating normally seen in switchgear applications where the VT is spec'd to be able to take the line-to-line voltage indefinitely, but is a single-bushing VT connected line-to-ground....so it's normally energized at 58% rated voltage. To my understanding it's rated...