I have a pile of contactors, on-off switches, indicator lights etc. One nema 0 contactor lists 480v on the coil, what does this mean exactly? Thank you.
Contactor, on-off switch Q
- Thread starter 930dreamer
- Start date
OP
Does the coil control the contactor operation ie latch/unlatch?
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If you wish to use a contactor w/ a 480V coil on another voltage, then the coil needs to be replaced w/ one having the correct voltage, but if the contactor is a DP, Definite Purpose contactor, the coil is not replacable as it it a throwaway item, common in HVAC & food service equipment.
That is not a latching contactor, but the coil does operate the contacts, SQ D type S contactors are common, & should be able to be found online. BTW the item pictured is not a contactor, it's a magnetic starter consisting of a contactor & a overload relay.
OP
Question- why does it list the other voltages/hp limits?
You may notice the voltage ,the higher the voltage, the higher the HP rating & it has nothing to do w/ the coil voltage, which could be anything from 24 to 600V & some are avail w/ DC voltages.
The HP rating is also altered by if it's single or 3Ø.
The HP rating is also altered by if it's single or 3Ø.
OP
A control transformer is common to supply the control circuit, some have many taps on the primary, most common are 240 X 480 V primary w/ 120V secondary, the user would connect the transformer for either 240 or 480V.
dave67fd
Well-known member
Correct. You can use the contacts in a single phase system if you want. Depending on the current your running through it which i'll guess is lower than the actual contact rating you need but the proper way to wire it is to connect each contact in series with the other (using all three contacts in a 1phase system). Hot input on A, hot output on F. Connect B-C and D-E.
A---l l----B
C---l l----D
E---l l----F
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OP
The control panel has a transformer, I thought it was used for all the (12)lights, on/off buttons. This is a little out of my knowledge field but, if I want to use the Nema 3 magnetic starter to operate/start a large three phase motor does the coil need to be 240v? Thank you for the help.
LennyTheLizard
Well-known member
Not trying to insult anyone's intelligence, but for someone who knows very llittle about electricity / controls:
The contacts on the relay (starter, etc) are like a light switch. If you have 3 phase power there are at least three contacts. Also there are usually Normally Open / Normally closed contacts (Light Switch is off when no power on coil (NO) / Light Switch is on when no power on at the coil (NC))
The coil acts as your finger on the light switch. When you turn on the coil you switch the contacts. The rating of the coil and contacts are not really related. The coil just has to be strong enough to open / close the contacts.
Relays / contactors come in many configurations, but most popular is for the coil to be controlled by a 120V AC, or 24V DC control circuit.
You just have to make sure that the contacts are rated for the load you are putting on them. ...And you must use the correct control voltage / amp rating for turning on / off the load.
On industrial equipment, usually you have the main voltage (480V / 240V 3Phase for example) supplying the breaker. Then you would have a step down transformer to get your control voltage (24V DC or 120V AC). This is the power that would usually supply the coil.
The contacts on the relay (starter, etc) are like a light switch. If you have 3 phase power there are at least three contacts. Also there are usually Normally Open / Normally closed contacts (Light Switch is off when no power on coil (NO) / Light Switch is on when no power on at the coil (NC))
The coil acts as your finger on the light switch. When you turn on the coil you switch the contacts. The rating of the coil and contacts are not really related. The coil just has to be strong enough to open / close the contacts.
Relays / contactors come in many configurations, but most popular is for the coil to be controlled by a 120V AC, or 24V DC control circuit.
You just have to make sure that the contacts are rated for the load you are putting on them. ...And you must use the correct control voltage / amp rating for turning on / off the load.
On industrial equipment, usually you have the main voltage (480V / 240V 3Phase for example) supplying the breaker. Then you would have a step down transformer to get your control voltage (24V DC or 120V AC). This is the power that would usually supply the coil.