relay contact welding

[jloom977]

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?

 

[Minder]

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]

Yes, it is an SCR controller. Yes the contacts do reverse the motor.

 

[Minder]

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.