Motor overload sensor
baron wrote:
Robert Baer Inscribed thus:
I have this circuit that will "trip" a PIC (as a controller), but
it
had no delay so i added a resistor.
SPICE circuit is attached.
The added resistor seems to give abou a 2 second delay to trip from
initial input drive.
But i know nothing about motors except that they work and have an
initial surge current which probably depends on load.
The idea is to shut down a machine by turning off the motor and
other
things if the motor has an excess load (gears seize, etc).
I do not know if that excess should be set to more or less that the
surge current; that is to say what is a "safe" method / setting?
Hi Robert,
In general, industrial motors have a current overload mechanism that is
thermally based. This allows any surge current to pass before it has
time to trip on over current. So unless you give time for any surge
current to subside before monitoring for overload, the surge current
plus a percentage would be the value to trip out at.
Thanks.
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