I should point out that, in my quick reply to Robbie, I may have
over-generalized a bit regarding fuse ratings. For a small motor
in good condition, like the one I tested with a 1.9 ampere rating,
a 3 Amp Slo-Blo fuse is quite suitable. Different motors, especially
higher horsepower or with different loads, may not fit this rule of
thumb. Larger motors may need fuses especially designed for motor use.
Fuse manufacturers provide average time current curves for different
fuse types. These can be used to evaluate the suitability of a specific
fuse. In the example of the motor I tested, a Littelfuse 3AG 3 Amp
Slo-Blo fuse will withstand more than 30 Amps for 100 milliseconds,
15 Amps for 1 second and about 7 amps for 10 seconds, gradually
decreasing to the fuse rating. This gives adequate starting capacity
while still providing protection after a short time.
Wayne Johnson - in Northern California for now, soon to be Idaho.
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