Maker Pro
Maker Pro

relay contact welding

jloom977

Jul 13, 2015
2
Joined
Jul 13, 2015
Messages
2
I am using an 1/8 HP motor with an SCR type dc drive and 1/4hp AC single phase control relays. I keep having a problem with welded relay contacts. Should I go to 1H/P relays? I dont know why I would have to being the HP of the motor is lower that the relay?
 
Last edited:

Minder

Apr 24, 2015
3,478
Joined
Apr 24, 2015
Messages
3,478
I assume this is a SCR bridge controller?
Are you using the contacts to switch the motor or reverse it, because the best scenario is to do what Manuf such as KB/Baldor do and turn the motor off with a Inhibit input, this also has the effect of causing the drive to come up through acceleration rather than full on.
BTW AC rating for relay contacts is quite a bit less than for DC.
M.
 

jloom977

Jul 13, 2015
2
Joined
Jul 13, 2015
Messages
2
Yes, it is an SCR controller. Yes the contacts do reverse the motor.
 

Minder

Apr 24, 2015
3,478
Joined
Apr 24, 2015
Messages
3,478
So is there any kind of inhibit on the controller, what make?
If no inhibit, you should ensure zero speed first before reverse, it is also easier on the drive.
M.
 
Top