telemec contactor question

[briwire]

I've come across a c strange telemech contactor with a combined overload. The contactor part has A1 and A2 which are obviously the coil connection, but in between there are two more connection E1 and E2. These are also connected to a supply.

I've not been able to check what does what yet apart from removing A1 de-energises the coil as you would expect. Any idea what E1 and E2 do?

 

[Spark123]

Some larger contactors have the facility to connect directly to a PLC on the ELV side to allow the PLC to control it directly, wonder if it is that.

 

[holmslaw]

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[GaryMo]

I've yet to come across heater coils, never heard of them.
What advantage would they have over an overload unit?

 

[Spark123]

I have come across overload units where the heaters are interchangeable, think they were made by MTE.

 

[holmslaw]

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[GaryMo]

Doesn't a thermal overload work in the same way, heat?

 

[holmslaw]

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[Spark123]

Yep, the current flowing through the coil creates heat. This operates a bi-metalic strip. If it exceeds the thermal set point then the unit trips. You have one heater per phase in the ones I have seen.
If a thermal device is not appropriate then you can consider using electronic overloads.
I still think the E1 and E2 are to do with ELV inputs tho

 

[GaryMo]

Yes but you lose the versatility.

In what way are they more versatile than a thermal overload if they both work by heat?

what size are heater coils? Are they din rail mountable or do they fit across the contactors terminals?

 

[GaryMo]

Yep, the current flowing through the coil creates heat. This operates a bi-metalic strip. If it exceeds the thermal set point then the unit trips.

Is that not how thermal overloads work also?

Unless your reply was a reply for my question "Doesn't a thermal overload work in the same way, heat?"?

 

[Spark123]

Yep, that is basically what the heaters are for.
If you want to get away from the thermal overloads for repeat stop starts then electronic units may be better.

As for E1 and E2, they can be supplied by the special modules on page 4 here: clicky, tho the ones I think I have seen were integrated, possibly made by AB.

 

[holmslaw]

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[holmslaw]

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