On 9 Aug 2005 06:22:06 -0700, "smitha4u"
wrote:

Hi Guys

Can any one suggest what are the various methods of performing bench
test for a 20 Kw(25HP) DC electrical variable speed motor.

Thank you
Regards
smitha

Assuming that such a motor has a wound field rather than permanent
magnet:

1) estimate rated field current by seeing what current results in a
steadystate temperature rise of about 20C with armature not excited.

2) With that field current applied, energize the armature with rated
voltage. Measure no-load speed and stall torque. (do the later
test quickly!) Measure armature current while stalled.

These tests are sufficient to determine the constants for the DC motor
equations describing speed and torque as fns of armature voltage,
armature current and field current.