NO IT WILL NOT.Yes it will!
You must treat the output rating the same as if it was configured with the two windings in series.
Wiring an Isolation Transformer
I found a pristine, never been used, Topaz (Square D Company) 91018-31 1.8 KVA Ultra Isolator Line Noise Suppressor for $40. Other markings include .0005pF, 50/60 Hz, 120/240, Indoor Type 1, Enclosure Class 1-80 Insulation. However, it has no receptacle or chord.
My first question to the forum, is how to wire it? Could I just take a short extension cord, cut in half, wire the male end to the output side and the female end to the input side? Should I use bare wire under the screw terminals, or should I crimp/solder on spades? What wires go on what screw terminals? Some suggest balanced is the way to go. But some suggest this cuts the power in half, some suggest it doesn’t. Here is an example I found of balanced wiring:
Input:
Neutral (white) to H1
Hot (black) to H4
Ground to chassis
Output:
Hot 1 (white) to X1
Hot 2 (black) to X4
X2/X3 center tap connected to chassis ground and outlet ground.
Is this all there is to it? I am a complete newb when it comes to electrical work. Is this something I can do myself, or should I hire an electrician? Any assistance would be greatly appreciated.
My first question to the forum, is how to wire it? Could I just take a short extension cord, cut in half, wire the male end to the output side and the female end to the input side? Should I use bare wire under the screw terminals, or should I crimp/solder on spades? What wires go on what screw terminals? Some suggest balanced is the way to go. But some suggest this cuts the power in half, some suggest it doesn’t. Here is an example I found of balanced wiring:
Input:
Neutral (white) to H1
Hot (black) to H4
Ground to chassis
Output:
Hot 1 (white) to X1
Hot 2 (black) to X4
X2/X3 center tap connected to chassis ground and outlet ground.
Is this all there is to it? I am a complete newb when it comes to electrical work. Is this something I can do myself, or should I hire an electrician? Any assistance would be greatly appreciated.
Showing 5 responses by jea48
120V in 120V out will not yield all that much isolation. Better to wire the xfrm 240V in, single ended 120V out. Series the primary windings, parallel the secondary windings. One paralleled leg of the secondary must be connected to earth ground making the new derived ac power system a grounded ac power system.... it's a safety thing. The earth ground used must connect to the main grounding system of the main electrical service. For this you would need to hire an electrician..... |
BTW I'm still curious how it is less isolated wired as 120-120.Did you take the time and read the Bryston link I provided? They recommend running the primary in balanced mode, 120/240V (120V 0 120V), instead of single ended 120V in. As for recommending the OP try it first.... As a rule I try to stay within the boundaries of NEC code as well as UL safety guide lines. NEC Article 647 Equitech . Curious, what are your thoughts on running the xfmr on 1/2 its designed rated voltage? (Series primary windings connected to 120V instead of 240V). What does it do to its efficiency? |
But some suggest this cuts the power in half, some suggest it doesn’t. Here is an example I found of balanced wiring:Wired balanced will cut the VA rating in half..... Wire the transformer 120V in 120V out. Parallel the two secondary windings together. Warning: Observe the correct polarity. If polarity is not followed the two secondary windings will buck one another possibly burning up the windings. Is there a data plate on the transformer showing wiring configurations? Primary? One winding or two? Input voltage/s? Number tags on leads? Polarity marking? Secondary? One winding or two? Secondary voltage/s? Number tags on leads? Polarity marking? |
Also, is there a definitive asnwer out there about balanced halfing the VA rating? Let me take a stab at it again.... First a power transformer is designed to operate at its rated nominal voltage and frequency. The size of wire used is directly proportional to the power the xfrmr is capable of delivering. The xfrmr you are looking to buy has dual primary windings and dual secondary windings. For the rated output voltage/power of the xfmr the primary can be wired for 120V in (paralleled) or 240V in (series) The FLA (full load amps) rating for the primary would be 15 amps @ 120V (1800Va / 120V = 15 amps) or 7.5 amps @ 240V (1800Va / 240V = 7.5 amps). Output of xfmr fully loaded... For the rated output FLA of the secondary of the xfmr the xfrm can be wired for 120/240V out (series the two windings, midpoint becomes the neutral) or straight single ended 120V out (parallel the two secondary windings) The 120/240V configuration is capable of delivering 7.5 amps @ 240V. (1800Va / 240V = 7.5amps) From each hot lead, leg, to the midpoint neutral of each winding is capable of delivering 7.5 amps @ 120V. (120V x 7.5 amps = 900Va. 900Va x 2 windings = 1800Va) L1 to neut 7.5 amps @ 120V.... L2 to neut 7.5 amps @ 120V. For your balanced 60/120V (60V 0 60V) wiring configuration you must use the above 240V calculation. The most FLA the xfrm will be safely capable of delivering will be 7.5 amps. 7.5amps x 120V = 900Va >>>>>>>>>>>>>>> So if each secondary winding is capable of safely delivering 7.5 amps @ 120V (as designed by the manufacture/size of wire used for the winding) then it stands to reason if both windings are connected in parallel (single ended) The xfmr would be capable of delivering 15 amps. 15 amps x 120V = 1800Va. Jim |