contactor va

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Praedatus1

Praedatus1

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Portland, Oregon
does anybody know what a general purpose 20 amp 2-pole contactor 24v coil draws (VA)? I am trying to run 5 of them from a 120-24 xformer, and cannot seem to find any ratings listed. I need to know what size xformer to get. The 5 contactors will be running at the same time. 50va? 100va?
thanks!
Tim
 
I have had to build bigger power supplies to get some contactors to work simultaneously. I would get the information off the contactors and take it from there otherwise you are just guessing. Also determine if you are using ac or dc before you design the control ckt.
 
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Praedatus1 said:
does anybody know what a general purpose 20 amp 2-pole contactor 24v coil draws (VA)? I am trying to run 5 of them from a 120-24 xformer, and cannot seem to find any ratings listed. I need to know what size xformer to get. The 5 contactors will be running at the same time. 50va? 100va?
thanks!
Tim
Click to expand...

Again maybe I'm totaly wrong!

5 transformer, 5 contactors as you stated it.
You supply voltage is in parallel but you voltage after transformation is now DC. And frankly that depends on the sum of usage downline, the resistance add in series, and again you have to proof accordingly.

Proof against your the line voltage after transformation.

Resistance in series

Wire derating, up sizing could come into play(required because one will assure proper voltage over distance).
 
no the xformers are 24v ac, and i want only 1 xformer to run 5 contactors... i might get a 3-wire contactor with a mechanical hold. then my VA doesnt matter as long as it can pulse 1 contactor.
 
Why not just hook up all of the contactor coils to a known-large enough 24v transformer and use a clamp-on to check the combined load current?

Or, use a voltmeter on the transformer you want to use, and connect one contactor at a time until the voltage sags significantly; no sag, no overload.


You'll have to excuse Cad. He thinks all transformers have built-in rectifiers, I guess. We try to keep him indoors and away from children and household pets.

Added: (He needs to jump in the ocean.)
 
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LarryFine said:
You'll have to excuse Cad. He thinks all transformers have built-in rectifiers, I guess. We try to keep him indoors and away from children and pets.

(He needs to jump in the ocean.)
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Soon, maybe ... I don't know, whats a vacation ?

I don't get to play with Low Voltage, just bring in the power!

After all their only pulling in and holding contactors!

Sorry Larry, you phrase is intact, I'm just on alot of Ignore Lists!

Here you Go OP, Search Full Bridge rectifiers here or take a look at contactors here.
Or you could post your Low voltage question there to or study other like posts / thread.
 
paul said:
What's the price difference between 50 and 100va?
Click to expand...
None, if the former goes on twice as long as the latter.


Or are you talking about transformers? :grin:



Seriously (hey, it could happen!), a 1a or 2a 24v x-former is too cheap to worry about the cost. (Radio Shack even has them)
 
Even at 20A (rating of OP contactor) the 24VAC coil to close can vary. Give us a model number if you can. At 40A (smallest I have ever done) I have used a close and hold circuit (I think one post alluded to such)

Is the budget so tight you can’t just buy something big? It costs more to think sometimes.

Even 100VA for five of these sounds small
 
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Praedatus1 said:
does anybody know what a general purpose 20 amp 2-pole contactor 24v coil draws (VA)? I am trying to run 5 of them from a 120-24 xformer, and cannot seem to find any ratings listed. I need to know what size xformer to get. The 5 contactors will be running at the same time. 50va? 100va?
thanks!
Tim
Click to expand...

EATON IT Contactor, NEMA Size 1, 27A continous rating.

24VDC Requiremens:
inrush(50ms): 3.8A/80W
sealed in:0.18A/4.2W
 
Praedatus1 said:
finally found it on cutler hammer website...41va inrush, 6.5va holding. Im getting a 150va to make sure! Thanks guys
Click to expand...

Didn't you or someone say you had 24Vac coils?

weressl said:
EATON IT Contactor, NEMA Size 1, 27A continous rating.

24VDC Requiremens:
inrush(50ms): 3.8A/80W
sealed in:0.18A/4.2W
Click to expand...

Did I miss something? Does Praedatus1 need a DC power supply?
 
quogueelectric said:
He said ac I swear.
Click to expand...

I thought so also but the reference to Cutler Hammer makes me think it is an IT contactor and I think they are all 24VDC. (I am rather positive)

If it didn't take so long to navigate through Eaton / Cutler Hammer's web site I would head over there ...
 
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