Matt Mckenzie
Member
- Location
- United States
on a 120volt definite purpose contactor does just the 120 volt power terminate to the contactor and energize the power or does the hot and the neutral terminate at the coil?
contactor question
- Thread starter Matt Mckenzie
- Start date
- Status
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The coil must be connected to something at each end.
It is physically possible to build a contactor with an internal jumper from one of the switch contacts to the coil, but AFAIK that is never actually done, even in a Definite Purpose device.
It is physically possible to build a contactor with an internal jumper from one of the switch contacts to the coil, but AFAIK that is never actually done, even in a Definite Purpose device.
Matt Mckenzie
Member
- Location
- United States
contactor again
contactor again
so on a 120volt definite purpose contactor the control power and the neutral both terminate on the contactor?
contactor again
so on a 120volt definite purpose contactor the control power and the neutral both terminate on the contactor?
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
If the control power is referenced to the neutral, yes. There will be two coil terminals and you can supply the needed voltage to them any way you want (within reason.)
mgookin
Senior Member
- Location
- Fort Myers, FL
In the below sketch we use a single pole contactor to control a load.
We only switch the hot leg of the load circuit. You still need a neutral going to the load.
We need both hot and neutral at the coil side of the relay to make the coil pull in to make the contact. That is controlled by S1 whereas S1 can be a SPST manually operated switch or any other control device like a building management system, a photocontrol, etc.
Think of it as two separate circuits (which it is). One circuit is the load. The other circuit is the control circuit.
So as you can see, the control (coil side) circuit ends at the contactor (most commonly). But the hot leg of the load circuit continues on to the load.
We only switch the hot leg of the load circuit. You still need a neutral going to the load.
We need both hot and neutral at the coil side of the relay to make the coil pull in to make the contact. That is controlled by S1 whereas S1 can be a SPST manually operated switch or any other control device like a building management system, a photocontrol, etc.
Think of it as two separate circuits (which it is). One circuit is the load. The other circuit is the control circuit.
So as you can see, the control (coil side) circuit ends at the contactor (most commonly). But the hot leg of the load circuit continues on to the load.
tyha
Senior Member
- Location
- central nc
the control power has its own neutral to hold coil once control circuit is energized. the circuit your "contacting" running through does not require neutral at contactor. just like a switch. contactor is a switch controled remotely or automatically via whatever the control or coil circuit being controlled by
tyha
Senior Member
- Location
- central nc
I may have screwed that answer up by misunderstanding. the control circuit is commonly referred to as the coil circuit and yes you need a neutral in order to create 120V potential between the control wire and neutral to create electromagnetism and pull contacts together
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
151203-2152 EST
Normally most relays or contactors are not manufactured with any electrical connection between the coil and the switched contacts. Not necessarily so on automotive relays.
Thus, if I have a voltage source that can power the coil, then that source can be at any voltage relative to earth (ground, netural) or hot conductor connected to a switch contact on the relay. The only limitation of the voltage difference between the coil and anything else is the breakdown voltage between the coil and the anything else.
.
Normally most relays or contactors are not manufactured with any electrical connection between the coil and the switched contacts. Not necessarily so on automotive relays.
Thus, if I have a voltage source that can power the coil, then that source can be at any voltage relative to earth (ground, netural) or hot conductor connected to a switch contact on the relay. The only limitation of the voltage difference between the coil and anything else is the breakdown voltage between the coil and the anything else.
.
- Status