OK I have a question for the group. I think there are some motor experts out there that can help me.
I have an older snow blower motor (5BC49JB131B HFN M). Series wound with a shunt coil that caps speed at 3100 rpm. Facing shaft power comes in and out on the left side, forword and aft terminals. both sides have external buss connections about 2 inches long joining two terminals. Someone on the group was nice enough to send a performance curve that shows:
2.5 hp continuous, 6.4 field amps, 3100 rpm no load, hp calculated from torque curve at 490 amps = 16.2 hp (680 oz ft, 2000 rpm, 68% eff)
The field amps is a perfect match to my motor. When I measure the motor resistance (using a four point measurement) however I get 102-124 milli-ohms (similar to e12M motor). Using this I would estimate the maximum output at (36/.100) 360 amps locked rotor. Assuming max power is at 1/2 speed and 50% eff, that would be (180 amps * 36 volts / 746 watts/hp * 50% eff) 4.34 hp.
I know in theory the brushes behave differently when spinning, with current through them. I have had good luck checking the resistance on other dc motors.
The motor works, but not like the curve I have. The brushes look good, but I have no idea if the springs are good. It pulls 30 amps when running on the bench. No evidence of hot terminals etc. New bearings last year.
Any tips for me to trace down the high resistance, proper brush load and or motor history on the snowblower motors?
Thanks,
Rob Brock way
_______________________________________________
Elect-ttrackmailing list
Elect-track cosmos pPhtufts Edi
HTTP://cosmos.pPhtufts.eEdimailman/llist infoeelecttrack