In the old days we would have may used a rotary converter. Looks like a motor with slip rings on one end and brushes on the other. I doubt if they are made anymore with all the power electronics that are available.
You did not say if this was an instrument transformer or power transformer. As has been mentioned this is a common secondary voltage for instrument transformers. Distance relays that require phase to phase voltage normally use the 67 volt (phase to ground) vt winding giving them 120 volts phase...
Check the Manta 5000. Only new set on the market that can run from the front panel. Designed by a relay tester, not some software geek who never saw a relay. Doble and Omicron very good test sets as well. I like RTS for software.
Ok, here is the link to the 3 dobles, expired but maybe you can track him down to repost.
http://cgi.ebay.com/Three-Doble-F-2500-Protective-Relay-Test-Sets-w-F-2010_W0QQitemZ7588087997QQcategoryZ50962QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
There was a set on ebay for 25K. Kinda spendy don't ya think? I've been looking for test equipment for the last couple of months and its really hit and miss. Its not a commodity so if no one else happens to be looking at it you may get it real cheap, especially if its something the seller...
Keep in mind there are third harmonic currents in the neutral of any three phase generator, even if the load is balanced. Add in any unbalance and you can have strange currents and voltages in the nuetral. You didn't say if the neutral is resistance grounded but I assumed it was.
See if you...
See IEEE C37.91 section 8.2.4 on overexcitation protection. The permissible overecitation of any given transformer or generator should be obtained from the manufacturer.
All of the above are possibilities. Begin by taking in-service load reading at maximum possible load. Read current magnitude and angle with respect to any reference voltage. Compare all 6 reading to see if the they are the proper magnitude and direction given the CT ratios and connections. Also...
2nd harmonic predominant on inrush, 5th on overexcitation just like stevenal says, but harmonics also appear at other times, i.e. sympathetic inrush when two transformers are in parallel and one is energized and the other is being energized. Harmonics appear in the energized bank as well as the...
When there is a standing positive DC on a wire, elctrolysis is a posibility. I'm not sure of the physics involved but thats why you always see control circuits with the contacts on the positive bus and the relay coils tied to negative.
The other possibility is the heat generated by the...
The term "rotation" is somwhat of a misnomer. Without seeing your drawing, you may be looking at a phasor diagram which is always shown on the nameplate of modern transformers and generators. As Mr. Wilson pointed out, to be meaningful, the direction of rotation of the rotor of the generator...
Its been over 10 years since I was testing on a regular basis, its mostly been demonstration of relays to customers. I don't have the current hands on to help you pick a model from experience.
Once you have it boiled down to 2 or 3 vendors ask them to send an application engineer (not a sales...
With single phase relays the most currents you would need would be two (to test a current differential). However, most of the microprocessor relays are three phase in one box. Also, not all manufactuers publish a method for testing three phase relays single phase. To further complicate things...
If your talking about your house, no. Most residential load is resistive, when the voltage goes down the current goes down, reducing demand. Motor loads like pumps, compressors in hvac systems and refrigeration units will pull more amps when the voltage goes down. We ran some tests at the...
