Universal Transformer


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Old 12-01-18, 10:03 AM
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Lightbulb Universal Transformer

Inline voltage is 2 lines of 120v and I have the transformer wired in for 240v (in) and 24v (out).

When I take a voltage reading it says 27v but shouldn't it read 48v? Pic is attached.

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Old 12-01-18, 10:30 AM
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I would expect 24 to 27 volts if it is a standard HVAC 24 volt transformer.
 
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Old 12-01-18, 10:39 AM
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A "universal" transformer has several leads on the primary to deal with 120, 208, or 240 VAC input so that the output is 24vac. A fixed 120 to 24vac transformer would indeed output 48vac with a 240vac input. Using the universal transformer's 120vac taps would also yield 48vac.
 
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Old 12-01-18, 11:13 AM
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A fixed 120 to 24vac transformer would indeed output 48vac with a 240vac input.
Yep..... and it would be smoking heavily before it fried.
 
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Old 12-01-18, 11:43 AM
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Transformer Wires are:
White = Common
Black = 120v
Red = 208v
Orange = 240v

I'm using the White and Orange wires for 240v
 
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Old 12-01-18, 12:13 PM
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and it would be smoking heavily before it fried.
I haven't done that in a while. Sometimes the smell isn't that bad.
I'm using the White and Orange wires for 240v
Then it is doing exactly what it is supposed to do - providing 24vac.
 
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Old 12-01-18, 01:43 PM
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OK I have one more question that ties into this ...

Does this mean it only takes 24v to power the fan switch and sequencer?
I watched a few videos where it has mentioned that they require 48v. I'm wondering if they is wrong.
 
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Old 12-01-18, 01:51 PM
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99.9% of HVAC equipment, controls, thermostats and relays run on 24vAC.
 
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Old 12-01-18, 03:41 PM
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Thank you for your help everyone !!!
 
 

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