three phase contactors damaged 6

[fab1961]

Dear all,

we got from a Customer of ours a picture of a Siemens contactor installed on our machine with a burnt contact.
The motor driven is 2.2 kW at 380 V 5.7 A, expected service category is a mix of AC3 and AC4 (Siemens model is 3RT1016-1BB41 which is rated 4 kW in AC3 and 2 kW in AC4). My question is since only one pole look burnt and since we have the problem on three machines (same motor, same contactor - excluding therefore motor problems) could it be that Customer line is unbalanced?

Thank you.

 

[ScottyUK]

That contactor has three main poles plus one normally open auxiliary contact which has a much lower rating than the main power circuit. Are you by chance connecting the power circuit to an auxiliary contact?


----------------------------------

If we learn from our mistakes I'm getting a great education!

 

[OperaHouse]

I agree with above, but if the right contacts were used I have another choice. It is stated 380V. Did the customer rewire this? Did you test it at 480, rewire it for 380 and Just ship it? I think the burnt contact has the associated motor winding wired backwards.

 

[itsmoked]

Agreed.
Auxiliary abuse.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

It's a common problem with those contactors. The same frame also comes in a 3RT1015... version, in which all 4 poles are rated the same. So people who have used that will buy the 3RT1016 and ASSume it is the same, but it is not. The "4th pole" is not really a power pole once you move off of the 1015 unit, it is an aux. contact for use on control circuits. They will look at the data sheet and see that it is "rated" 10A and think that's better than they need, but that is not the AC-2 or 3 duty rating, that is a control circuit rating, I think it's something like AC-15. For non-resistive loads it is only rated for something like 3A max.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376