Hi all,

Can some one point me in the direction for motoer and cable amps?

I have a Q.
A 1500HP D.C. motor compound wound, reversible,
Shunt rated at 100Amps.

How do I work out total amp requirements, I believe this motor runs at 750 Volts.

Exactly, what do you want to run on the end of this 1500HP motor?.
Next question would be, do you have a DC supply large enough to supply it?.


[This message has been edited by Trumpy (edited 10-25-2006).]

An average DC motor draws an armature current of approx 1.5A per HP at 550V.

The armature current varies inversely to the applied voltage so in your case:

1500HP * 1.5A/HP * 550V/750V = 1,650A.

Note that you can't use standard building wire for this application because the armature voltage is above 600 volts. I have used DLO/RHH for this application a number of times. The last 1500 hp DC motor that I worked on needed cables rated for 2156 amps (motor FLA at 1725 times 1.25 for wire size). We used the ampacity for 500 kmil derated to 344 amps because of 4 current carrying conductors in each raceway. The calculation only required 7 sets or conductors, but because of the rules in 310.4 we had to use 8 sets. We had four 4" conduits, each with four 535.3 kcmil DLO cables.
Don

Out of pure idle curiosity what was a monster like that turning.
--
Tom Horne

Tom,
The one I was working on is an extruder drive motor. That extruder is used for the final step for making ABS plastic pellets. The ABS resin and the addatives for color and other properties are fed into the extruder and and mixed and heated by the screws and forced out of the die head in about 130 3/16" strands that are then cooled in a water bath and sent to a pelletizer to cut them in to pellets about 3/16" long and then bagged, boxed or bulk shipped to the customer who will mold the plastic into a final product.
By the way those 8 535.3 kcmil DLOs were connected to 4 4/0s in the motor junction box. We had to add a box extension and a bus detail to make the transition from the size of wire required by the code to the internal motor armature leads.
Don