I work on a bit of kit now and again that comes from the USA, for now we shall say that they power ac motor via contactors/relays.

When I get them the contactors (that have 2 sets of norm open contacts) are always wired in series ....... I always change it to parallel to spread the load across the contacts.

Is this a good idea or bad ?
Is there any advantage to powering a motor through 2 seperate contacts in series ?

 

I work on a bit of kit now and again that comes from the USA, for now we shall say that they power ac motor via contactors/relays.

When I get them the contactors (that have 2 sets of norm open contacts) are always wired in series ....... I always change it to parallel to spread the load across the contacts.

Is this a good idea or bad ?
Is there any advantage to powering a motor through 2 seperate contacts in series ?

I think the series relays are for the purpose of "step starting". Usually the first set of contacts applies a resistance to reduce the starting current, then the "final" relay kicks in, bypassing the first one.

Eric

 

I think the series relays are for the purpose of "step starting". Usually the first set of contacts applies a resistance to reduce the starting current, then the "final" relay kicks in, bypassing the first one.

Eric

I cannot comment on this technique as I have no experiance on it but the contactors I am dealing with have no clever delay or resistance, just 2 "no" & 2 "nc" (the "nc" get used in the brake circuit).

Both the "no" contacts are driven by the same solenoid so they close as a pair.

 

hi can u send me the links for otc cranes?
i need 2 make documentation on it....
so plz send me the details..........