Eliminating inductive kick
Eliminating inductive kick
(OP)
I am using relays to turn 24 small DC motors (250mA each) on and off thousands of times per day in a testing application. The relays seem to fail after several months of use and I am suspecting inductive kick as the cause of the problem since there is no snubbing circuitry wired into the testing device.
What should I consider when designing a circuit to suppress the inductive kick.
I have seen solutions involving diodes in parallel with the relay as well as tank circuits. Is there a disadvantage to using only a diode (this is the way I was planning on going)? Should I choose a diode that can handle the same amount of current that the motor requires? Are there any other specifications I should look at?
Any help will be appreciated. Thanks,
David.
What should I consider when designing a circuit to suppress the inductive kick.
I have seen solutions involving diodes in parallel with the relay as well as tank circuits. Is there a disadvantage to using only a diode (this is the way I was planning on going)? Should I choose a diode that can handle the same amount of current that the motor requires? Are there any other specifications I should look at?
Any help will be appreciated. Thanks,
David.





RE: Eliminating inductive kick
Gunnar Englund
www.gke.org
RE: Eliminating inductive kick
RE: Eliminating inductive kick
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Eliminating inductive kick
BTW. A motor that is running does not produce much of an inductive kick when you break the circuit. It is not at all like breaking current to a coil. I do not think that a diode changes much.
How many motors do you have per contact? What relay type are you using?
Gunnar Englund
www.gke.org
RE: Eliminating inductive kick
RE: Eliminating inductive kick
and using solid state switches.
Plesae read FAQ240-1032
My WEB: <http://geocities.com/nbucska/>
RE: Eliminating inductive kick
http://www.keithley.com/data?asset=394
Note the 108 closures rated life, but they degrade to 105 closures at max signal, which is 1 A in this example.
TTFN
RE: Eliminating inductive kick
RE: Eliminating inductive kick
Replace with MOSFETS. Suitable parts can handle
the current for about $3.00
Also do put a diode across the motor so that stored
energy circulates in the diode and not produce a
kick.