Electrician Talk banner
1 - 2 of 2 Posts

·
Registered
Joined
·
42 Posts
Discussion Starter · #1 ·
Hello I was wondering if anybody had any rule of thumbs or ideas on how to size either a capacitor or diode or both for protection on a relay contact. At work we have a lift machine, roughly 15 feet vertical and the contactor circuit for the dc brake on the motor sometimes sticks so therefore the lift slams to the ground very randomly nearly killing operaters. I'm looking to prevent this by shunting a capactive, diode circuit across the contacts. The voltage is 120ac. Thx for any info.
 

·
Registered
Joined
·
5,512 Posts
Hello I was wondering if anybody had any rule of thumbs or ideas on how to size either a capacitor or diode or both for protection on a relay contact. At work we have a lift machine, roughly 15 feet vertical and the contactor circuit for the dc brake on the motor sometimes sticks so therefore the lift slams to the ground very randomly nearly killing operaters. I'm looking to prevent this by shunting a capactive, diode circuit across the contacts. The voltage is 120ac. Thx for any info.
Your description is not clear.

You have a Hoist Motor with a DC brake where the brake coil is separately controlled by a contactor, and the contactor is sometimes not releasing to drop out power to the brake coil, so the brake is not engaging and the load is falling? If so, I don't think this has anything to do with "shunting a capacitive, diode circuit across the contacts", whatever that means. If your brake coil contactor is not releasing, it is either welding, in which case it is not the right contactor, or it is something improper in the control circuit.
 
1 - 2 of 2 Posts
Top