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Anonymous Poster

Magnetic Contactors and Single-Phase Power Supplies

05/21/2009 6:23 PM

can 3 phase electrical magnetic contactor be operated in single phase power supply?

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Power-User
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Location: Christchurch, New Zealand
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#1

Re: electrical contactor

05/21/2009 8:39 PM

Yes, it can. It is commonly done where larger lighting loads are switched. The single-phase feed is commoned on the 'L' side of the contactor, and each connection on the 'T' side of the contactor feeds a separate set of subcircuits. Just make sure that the coil is of the correct voltage rating.

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paulusgnome
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#4
In reply to #1

Re: electrical contactor

05/21/2009 9:21 PM

Thanks for the information.

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Guru

Join Date: Apr 2007
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#2

Re: electrical contactor

05/21/2009 8:54 PM

"can 3 phase electrical magnetic contactor be operated in single phase power supply?"

Can you please re phase your question again?

What do you mean by 3 phase electrical magnetic contactor be operated in single phase power supply?

Are taking about, the energizing of the magnetic contactor coil using single phase supply or are you talking using the contact point of the contactor for single phase load usage.?

Your question is not clear

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#3
In reply to #2

Re: electrical contactor

05/21/2009 9:19 PM

Thanks for your immediate response. My question is, we already have a three phase magnetic contactor can we energize it using sigle phase supply?

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Guru

Join Date: Apr 2007
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#5
In reply to #3

Re: electrical contactor

05/21/2009 9:31 PM

Your question is still not clear.

I presume that your 3 phase contactor coil is rated at 415v and you want to use single phase voltage of 240 v to energise your contactor. Am I right.?

Well the answer is NO. Your single phase voltage is not able to energize your 415V contactor coil. BUT....

You can change your 3 phase contactor coil rated 415v to the single phase 240v coil. Most of all the contactor in the market, the contactor coil is interchangeable to suite the voltage requirement.

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Power-User

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#6
In reply to #5

Re: electrical contactor

05/22/2009 2:53 AM

Nice respond Simon Wan,

additional question is :

when we are talking about 1 phase. is it

1. phase to neutral (neutral from center of Wye): 415 / √3 = 240 volt , or

2. phase to neutral (neutral from center of one side of delta) : 415/2 = 207 volt, or

3. phase to phase : 415 volt

R - S : 415 volt

S - T : 415 volt

R - T : 415 volt

I

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Guru

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#7
In reply to #6

Re: electrical contactor

05/22/2009 3:34 AM

Yes. When we say 1 phase or Single phase supply, we will consider as a phase to neutral power supply (for the case of star point transformer) in which for phase to neutral (neutral from center of Wye): 415 / √3 = 240 volt

But if we are talking about, 1 phase or Single phase supply for the Delta type, then actually, the phase voltage = Line voltage = 415 volt.

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Anonymous Poster
#8

Re: Magnetic Contactors and Single-Phase Power Supplies

09/11/2009 7:34 PM

yes because only magnetic contactor is 3 phase and the coil of magnetic is 220 yes can operate. josetech_@hotmail.com

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Anonymous Poster (1); elect-ok (1); josejordan_fernandez711 (2); Paulusgnome (1); Simon Wan (3)

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