overloaded stepper blow fuse?
- Thread starter realolman
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petersonra
Senior Member
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- Northern illinois
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- engineer
Highly unlikely if the fuse was sized correctly. The stepper drive would shut down first.
I suppose there could be some obsolete or poorly designed drives where this is possible though.
There are a lot of hobby type stepper drives out there that are not real spiffy.
I won't pretend to be any kind of expert on the subject, but I thought the drive would have to have something to limit the current under normal operating conditions anyway, and I always thought if the stepper were mechanically stalled, it just wouldn't turn... I did not think that it would cause any kind of overcurrent in the drive.
course I often think wrong
petersonra
Senior Member
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- Northern illinois
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- engineer
I think you have summed it up. Unless someone undersized the fuse.
I don't think I have ever run across a stepper drive that did not limit the current.
- Location
- San Francisco Bay Area, CA, USA
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- Electrical Engineer
I agree, a Stepper drive is to a certain extent inherently current limiting in that if you give the motor a step pulse and the motor doesn't move, the drive just moves on to the next step pulse. It's not like an AC motor that is relying on the motor inductance to limit the current flow, the current that flows to any motor pole is limited by the internal resistance of the pole itself. Not moving the rotor past it makes little difference in the maximum amount of current that pole will draw. The main reason some have current limiting is because if you are doing micro steps (partial steps), you may want to limit the current on a leading or lagging pulse to LESS than full current while the main pulse is at full current, but that doesn't need to be there at all in a drive that is not using micro stepping. Variable Reluctance High Torque stepper drives also have current limiting because they tend to use high peak voltages to get more torque, so they have to limit current to avoid damage to the drive. So more likely the fuse was under sized to begin with as he said.
But now that I think about it, if someone tried to use a high torque stepper motor on a drive that was not designed for controlling a high torque stepper motor and therefore did not have current limiting at all, maybe that would explain it.
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