ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Danish type K Sockets
by dsk - 02/23/20 02:42 AM
15 amp outlets removed due to cell phones
by BigB - 02/20/20 07:23 PM
Square D "All-In-One" Panelboard
by gfretwell - 02/18/20 07:38 PM
2020 code
by shortcircuit - 02/11/20 04:30 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 5 guests, and 8 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
1500HP D.C. motor amps #130710 10/21/06 10:57 AM
Joined: Oct 2006
Posts: 1
Jaz Offline OP
Junior Member
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.

Tools for Electricians:
Re: 1500HP D.C. motor amps #130711 10/25/06 11:54 AM
Joined: Jul 2002
Posts: 8,277
Trumpy Offline
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).]

Re: 1500HP D.C. motor amps #130712 10/25/06 03:22 PM
Joined: Jul 2001
Posts: 599
JBD Offline
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.

Re: 1500HP D.C. motor amps #130713 10/26/06 07:30 AM
Joined: Nov 2000
Posts: 2,148
resqcapt19 Offline
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.

Re: 1500HP D.C. motor amps #130714 01/05/07 11:34 PM
Joined: Mar 2001
Posts: 345
tdhorne Offline
Out of pure idle curiosity what was a monster like that turning.
Tom Horne

Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
Re: 1500HP D.C. motor amps #130715 01/07/07 06:18 PM
Joined: Nov 2000
Posts: 2,148
resqcapt19 Offline
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.



2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman


Member Spotlight
Posts: 421
Joined: September 2005
Show All Member Profiles 
Top Posters(30 Days)
dsk 6
djk 5
Admin 3
cgw 2
Popular Topics(Views)
263,575 Are you busy
198,655 Re: Forum
187,551 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3