E-water pump failure notifier?
If you can wait a minute or two, ECT ought to go
through the roof.
If the pump quits it ought to either be open circuit
(zero current) or locked-rotor (high current), both
can be sensed with a low value resistor (select so
normal pumping gives you maybe 500mV voltage
drop, ground side, and you'd have plenty of signal
for a pair of comparators to reliably detect under
or overcurrent.
through the roof.
If the pump quits it ought to either be open circuit
(zero current) or locked-rotor (high current), both
can be sensed with a low value resistor (select so
normal pumping gives you maybe 500mV voltage
drop, ground side, and you'd have plenty of signal
for a pair of comparators to reliably detect under
or overcurrent.
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If you can wait a minute or two, ECT ought to go
through the roof.
If the pump quits it ought to either be open circuit
(zero current) or locked-rotor (high current), both
can be sensed with a low value resistor (select so
normal pumping gives you maybe 500mV voltage
drop, ground side, and you'd have plenty of signal
for a pair of comparators to reliably detect under
or overcurrent.
through the roof.
If the pump quits it ought to either be open circuit
(zero current) or locked-rotor (high current), both
can be sensed with a low value resistor (select so
normal pumping gives you maybe 500mV voltage
drop, ground side, and you'd have plenty of signal
for a pair of comparators to reliably detect under
or overcurrent.
Here's a sketch, it's a basic window comparator
(you could find similar in the application notes
at www.national.com, LM339 comparator apps).
Lights the light if pump motor current sense is
too low or high, you have to select the sense
resistor so that it drops 500mV at normal.
(you could find similar in the application notes
at www.national.com, LM339 comparator apps).
Lights the light if pump motor current sense is
too low or high, you have to select the sense
resistor so that it drops 500mV at normal.
