30 amp in-line fuse continually blows
Boy do I need some help! Every time I try to extend the landing gear on our 5th wheel when hitching or unhitching the 30 amp inline fuse blows after a few seconds. We had this problem a few years ...
Forum Discussion
MEXICOWANDERER wrote:
it is common for an AC motor to draw more amperage with low voltage - impossible for this to happen with a brush type DC motor UNLESS
Muy incorrecto-mundo... With an AC motor, the output goes down with lower voltage and varies as the square of the voltage too. (EE 101) Motors take a bigger and bigger hit as voltage drops. At say 50% of rated voltage, output drops to 25% (1/2 x 1/2) and current to 50% (using ohms law I=P/E). AC units are an exception however and current goes up.
No idea on the OP's issue tho... Maybe try disconnecting wires at the motor and see if fuse still blows? Found this on another RV forum: When a DC motor runs, it creates "back electromotive force" or "back EMF." This back EMF limits the currrent flow through the motor. If the motor stalls, the back EMF goes away and the stall current will increase above the running current. If the system isn't designed for this, the stall current can blow the fuse. I've never dealt with slideouts, so I don't know if they are set up with a limit switch that kills the power at end-of-travel or if they're designed to stall out at end of travel. If it's the former, the limit switches may not be making up and the motor is stalling at end-of-travel and pulling enough current to blow the fuse. Maybe this can happen on landing gear too?
