engineerftw
Newbie
Hi. I have a 12v circuit that controls two relays that switch power a 120v motor. The motor has a limit switch inside. See diagram below.
When the limit switch trips, it creates a spike of conducted EMI that induces EMI in the 12v lines which wreaks havoc in the rest of the circuit (not pictured).
The problem is that the motor and limit switch are difficult to access. I only have easy access to the junction box, which has only one of the 120v lines that power the motor.
In an ideal world, I'd put a snubber or something across the motor and/or limit switch, but that's not really feasible due to access issues. The EMI is below 1 MHz (it seems to be around 400kHz), which is too low for most ferrite beads to filter. I was going to try some shunt capacitors on the 12v lines.
I was wondering if anyone has suggestions for other things to try? Maybe ferrite on the single 120v line that runs into the junction box?
-Josh
When the limit switch trips, it creates a spike of conducted EMI that induces EMI in the 12v lines which wreaks havoc in the rest of the circuit (not pictured).
The problem is that the motor and limit switch are difficult to access. I only have easy access to the junction box, which has only one of the 120v lines that power the motor.
In an ideal world, I'd put a snubber or something across the motor and/or limit switch, but that's not really feasible due to access issues. The EMI is below 1 MHz (it seems to be around 400kHz), which is too low for most ferrite beads to filter. I was going to try some shunt capacitors on the 12v lines.
I was wondering if anyone has suggestions for other things to try? Maybe ferrite on the single 120v line that runs into the junction box?
-Josh