wound rotor motors

How would one size the overcurrent protection and conductor to a wound rotor motor with a liquid rheostat.

The following is the info I currently have:

Hp =1500 RPM = 889 Volts = 4160 Stator amps = 190 Service factor 1.15 Secondary volts = 995 Secondary amps = 689

The control protection is a Westinghouse IQ-1000 protective relay

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AHHHHH the ole IQ1000 an dinosaur now days. Are you sure it is not a 1000 II?

Get out the IQ 1000 manual. There is a table in the back plug in the numbers to the table and your almost done. No manual, Eaton Electric has them on line in pdf format. Make sure you have some time to get through their web page.

I have no clue what a liquid rheostat is so I am not going to venture into anything more. If you have no idea of how to size the overcurrent then telling you the conductor size could be a accident looking to happen.

Medium voltage is not something to play with.

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I once saw a setup where the three rotor leads were brought out to three large metal 'blades' suspended above a tank of 'electrolyte' (caustic soda in water). The blades and leads were insulated from each other, and lowered/raised in the tank by a three ropes wound on a common shaft. Lower into tank so more blade is submerged reduced resistance, raise out of tank so less of blades was in tank, higher resistance.

Could dissipate quite a few KW that way, but had to circulate 'electrolyte' through a water-cooled heat exchanger to keep it from boiling.

Another time, a similar tank with three blades was used as a load bank to test run a 2000 kw generator. But this time, the shipyard folks just filled the tank with saltwater and let it boil. Just topped it off each shift (was doing 48 hour full load test on the unit).

daestrom P.S. Needless to say, the metal tank in both cases had to be well grounded for safety ;-)

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As far as conductor sizing, it is no different than any other motor.

125% of the Motor FLA, then up to the next available size after calculating for voltage drop over distance. Size the SCPD to the wire. The same holds true for the rotor conductors.

Why would you th>How would one size the overcurrent protection and conductor to a wound

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Bob Ferapples

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