Quote:
Originally Posted by cleeds
Hmmmm, this doesn't sound quite right. How can you get two 120V 20A circuits + one 120V 10A circuit from one 240V 30A circuit? They can't possibly be truly independent circuits, correct?
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How do you get multiple 120 volt circuits from your single 240 panel ?
The Equi=Tech ties into the 240 panel and then uses a balanced power isolation transformer to generate the individual 120 volt circuits from the single 240 feed.
amps * volts = watts
240 volts * 30 amps = 7,200 watts (maximum input into the isolation transformer)
120 volts * 20 amps * 2 = 4,800 watts (maximum outputs 1 & 2)
120 volts * 10 amps = 1,200 watts (maximum output 3)
(4,800 + 1,200 watts) = 6,000 watts < 7,200 watts (Note: 3 * 120 volts * 20 amps = 7,200 watts, but Equi=Tech probably designed in a safety margin)
I would assume the 3 circuits derived from the 240 volt / 30 amp feed comes from the multiple secondary windings in the specific isolation transformer being used.
See Equi=Tech's spec page for more details.
http://www.equitech.com/products/rack/modelqpro.html
See also: Multiple winding transformers:
http://www.electronics-tutorials.ws/...nsformers.html
I would assume the transformer being used would be something similar to the one pictured below, but with 1 primary input winding and 3 secondary output windings (as well as balanced power +/- 60 volts/120 volt differential on the secondary wirings).
Someone that knows more about transformers (especially 240 volt transformers) can correct me if my assumptions are incorrect.
Also: There is a 240volt/30amp breaker in the service panel and separate 120 volt 10 and 20 amp breakers in the Equi=Tech. From the calculations above, the breakers in the Equi=Tech would appear to trip before the breaker in the service panel.
Here is what a balanced output transformer would look like (the 240 volt versions would also incorporate 2:1 step-down windings):
