KB Electronics - How to choose the right horsepower resistor (HP) and armature fuse?

Posted by Kenny Rutschow on

Picking the proper horsepower resistor and fuse all depends on your application. Most motors come with plenty of specs of information on the nameplate of what horsepower it can run, however, if your motor is old or heavily used it can't be read you might need to use a multimeter.

In order to determine which to select, the things to look at are:  armature voltage (VDC), amperage, and the horsepower (HP). Here you can see both horsepower and fuse chart to determine which you need for your motor:

When picking the resistor, you use the voltage rating and horsepower in reference with the chart to select the line that will determine the part number. For example, if you voltage is at or between 90-130 VDC and the horsepower rating is at 1/2 HP, your resistor will be KB-9841
***Be sure the amperage is near the rating (amps DC), otherwise the motor controller may end up not working with your motor.


When choosing the armature fuse, you use the same rules as would with resistor chart above, but when finding which part number in our store you will be looking for Bussmann model MDA. As an example if your fuse is the part number 9744, you will actually use the AC Amps rating to determine the Bussmann fuse, which is MDA-8-R. 


Some motor controllers already have pre-installed resistors and fuses. AC motor controllers do not need these accessories, but some or most DC motor controllers need these to operate. In order to find out, you can check each of our listing for description, check each manual, or use this chart:

PLEASE NOTE: Depending on the motor controller, some may require a heatsink accessory to handle certain horsepower ratings. Refer to the drive's (motor controller) manual to see which ratings require a heatsink.


Other drive models, like the KBPC, will have all-in-one plug-n-play to where you will not need to purchase all the accessories except for switch functions like Forward-Brake-Reverse and all. Some drives are indoor, some are outdoor, others are hybrid, others have digital interface and some analog. So there are many options depending on your environment.