change mechanical contactor to electrically held

[tyha]

we have 4 different sets of different size lighting contactors (all mechanically held) controlling some lighting circuits. the coil for these contactors is being held by a Lighting Control Panel that does not send out a momentary pulse. its either on or off. it has to run through the LCP so the owner can monitor what lights are on and shut off remotely. how do I change these contactors. They are Eaton versions. 20 poles each ( 10 double poles). take off the little thing in the front and remove the holding coil in the back makes it sound like a buzz saw. there is something Im missing. Had I known the LCP's relays were maintained only I would have gotten electrically held. but all this stuff is fiquired by our vendor . which he really didnt know in this case that the LCP was going to hold the coils. it also controls just other regular lighting circuits as well and we are at the finish line so there is no return for electrically held.

 

[Smart $]

Got exact make, model, PN...???

 

[iwire]

Add a SPDT relay in the control circuit to provide an on and an off signal.

Most mechanically held contactors do not have to have a momentary signal, they have internal contacts that open the coil circuit once it changes state so they can work with momentary or maintained control input.

 

[hillbilly1]

If it's the model I think it is, the coil is actually DC, and what you removed was the clearing contact and rectifier, that's why it sounds like a buzz saw! The coils on mechanically held contactors are not designed to be continuosly powered, hence the clearing contacts or control module that delivers a pulse to the coil.

 

[texie]

If it's the model I think it is, the coil is actually DC, and what you removed was the clearing contact and rectifier, that's why it sounds like a buzz saw! The coils on mechanically held contactors are not designed to be continuosly powered, hence the clearing contacts or control module that delivers a pulse to the coil.

I'm not sure why you would want to go to electrically held especially if you already have a mechanically held. As others have said, just add a SPDT interposing relay and the maintained contact should not be an issue as most have a coil clearing contact.

 

[tyha]

Got exact make, model, PN...???

its an Eaton C30CNE with a 320MH2WAO mechanical CONTROL MODULE already installed on the front with wires to a 3 wire terminal strip. Right now it opens and closes with momentary voltage. there is actually a video @ Eaton.com that shows how to add the control module and holding spring in the back to make a mechanically held contactor out of the C30CNE but when we remove all that stuff and it should just be electrically held it makes a great noise when energized. I know electrically helds make some noise but there is something Im missing here. There has to be a way i can just use that piece of equipment and make it so its only held under voltage.

 

[hillbilly1]

That type is sold under a bunch of different manufactures, I don't know who actually makes them, but GE also puts their name on them too, they use a single coil that moves the plunger up, it hooks, then power is removed. When power is applied to the coil again, it unhooks the plunger allowing it drop out. They are a piece of junk, and you will be replacing it sooner than later. There is a two wire conversion kit that will convert it to "electrically held", but you will need a 24 hour hot for the control module to work. Otherwise, you will have to change the coil out to the one used in the regular electrically held contactor.

 

[Smart $]

its an Eaton C30CNE with a 320MH2WAO mechanical CONTROL MODULE already installed on the front with wires to a 3 wire terminal strip. ...

First, I am not familiar with these units... but from the instructions I gather you do not need to change your units to electrically held. The 320MH2WAO module is for two-wire 120Vac control. Two-wire modules appear to be for steady-state ON-OFF control, i.e. not momentary. Momentary signaling would require a three-wire control module. Refer to the wiring diagrams for pilot devices on the last page of instructions. Note the two-wire modules use ON-OFF(-AUTO) selector switches, whereas the three-wire modules use pushbuttons or spring-return selector switches.

Instructions: http://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/1081448184818.pdf

 

[hillbilly1]

First, I am not familiar with these units... but from the instructions I gather you do not need to change your units to electrically held. The 320MH2WAO module is for two-wire 120Vac control. Two-wire modules appear to be for steady-state ON-OFF control, i.e. not momentary. Momentary signaling would require a three-wire control module. Refer to the wiring diagrams for pilot devices on the last page of instructions. Note the two-wire modules use ON-OFF(-AUTO) selector switches, whereas the three-wire modules use pushbuttons or spring-return selector switches.

Instructions: http://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/1081448184818.pdf

As I noted in my post, you will also need an unswitched hot along with the switch leg in order to use the "Two wire control" All the two wire control module does is provide the pulse the contactor needs to operate, that is why the unswitched hot is needed.

 

[iwire]

First, I am not familiar with these units...

Be happy about that, they are real junk.

And as was pointed out in some applications they need constant hot control circuit.

 

[Smart $]

As I noted in my post...

Yeah, but you didn't elaborate on "electrically held"... The wiring diagrams I reference previously show no interconnection between control and coil wiring. As such, the coil could be a different voltage. Could be the reason he's getting the noise when he tried converting. Also, diagrams show no full-time "hot" connection on the control side???

 

[Smart $]

Be happy about that...

Okay

 

[iwire]

Okay

I am in the habit of ordering them with extra poles because more than once a pole was broken on arrival.:roll:

 

[Strife]

we have 4 different sets of different size lighting contactors (all mechanically held) controlling some lighting circuits. the coil for these contactors is being held by a Lighting Control Panel that does not send out a momentary pulse. its either on or off. it has to run through the LCP so the owner can monitor what lights are on and shut off remotely. how do I change these contactors. They are Eaton versions. 20 poles each ( 10 double poles). take off the little thing in the front and remove the holding coil in the back makes it sound like a buzz saw. there is something Im missing. Had I known the LCP's relays were maintained only I would have gotten electrically held. but all this stuff is fiquired by our vendor . which he really didnt know in this case that the LCP was going to hold the coils. it also controls just other regular lighting circuits as well and we are at the finish line so there is no return for electrically held.

Most mechanically held contactors have their coil control ran through an auxiliary contact, so as soon as the contactor goes in the other position, the coil for that position is not energized anymore.

 

[hillbilly1]

Most mechanically held contactors have their coil control ran through an auxiliary contact, so as soon as the contactor goes in the other position, the coil for that position is not energized anymore.

This type is a little different, it uses only one coil which moves the plunger up and hooks when power is removed, when power is applied the second time, the plunger moves up again, unhooking it allowing the plunger to fall changing the state of the contacts. (N/O & N/C contacts can be added by changing the contact blocks)