Difference between NRL, RDC, Motor Hp 1

[Tagger]

What is the difference between NRL, RDC, and Motor Hp?
I have been provided with info stating a:
NRL, Hp = 7
RDC, Hp = 19
Motor, Hp = 20

 

[ccw]

Hi Tagger,
Having looked through the NEMA and IEC glossaries and finding no direct definition, I will venture a WAG:

NRL = 7HP is the rating with no minimum rotor speed limitation, ie. could be 99% slip at some continuous about to stall torque, or cyclic reversing actions never reaching 5% slip speed.

RDC = 19HP is the rating for "continuous duty" service, a constant torque at about 5% slip that allows a winding temperature to stabilize that is just below the winding insulation rating. This is usually intended for approx. 20 or 25C ambient at sea level.

Motor HP = 20HP is the rating for a "service factor" somewhat less than "continuous duty". The service factor should be on the name plate.

 

[Skogsgurra]

Those terms were used (and are probably still used) for specifying drives for machinery. I saw them a lot during the eighties and mostly for paper machine drives.

NRL is Normal Running Load and that is the load that a motor was supposed to see in normal duty.

RDC is Recommended Drive Capacity and that is the load that the drive must be able to cope with during acceleration and braking.

I think that a guy named Derrek (forgot his first name) has written a lot about this. Do a google search to find out more.

 

[smckennz]

Have a look at section 3 in the following link:

http://66.102.11.104/search?q=cache:5FS62WLPXSUJ:

http://www.wempec.wisc.edu/reports/2001/01_27.PDF+NRL+RDC+Motor&hl=en&ie=UTF-8

Cheers

Steve