Will it work?

[rcdallas]

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[wtdoor67]

What is it supposed to be?

[rcdallas]

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[topgroove]

unfortunatly the sine wave from A and C are still 120 degrees apart. they're are almost out of sync with each other but not quite. if you look at the three sinewaves on a occillascope you'll see its close but no cigar. if you had two phases 180 degrees apart I can see that working

[Pootnaigle]

Ummmmmmmmm No It wont work like its drawed.

[topgroove]

unfortunatly the sine wave from A and C are still 120 degrees apart. they're are almost out of sync with each other but not quite. if you look at the three sinewaves on a occillascope you'll see its close but no cigar. if you had two phases 180 degrees apart I can see that working
ee phase sine wave

[T-Man]

First the two H2 bushings(not drawn here) need to be hooked up to comon and even grounded or that drawing in dead in the water.

Second the primary vectors (did I say that?) are not the same for A Phase or C phase so the secondary vectors would be 120 degrees out of line with each other.

third the secondary neutral could be comon between the pots but you will need to cut some splits in the main between the a's and b's or that mess will never close without a blow.

What would most likely happen when you closed one cut out, before you could close the second, back feed would impose a voltage greater than the open cutout could insulate or isolate for and you'd get a flash across the second cutout. You would have a reverse A phase primary vector on the bottom of the second cutout and a correct C phase vector on the top causing some issues. . .This is where senority comes into play. . . .

[Highplains Drifter]

What would most likely happen when you closed one cut out, before you could close the second, back feed would impose a voltage greater than the open cutout could insulate or isolate for and you'd get a flash across the second cutout. . . .

T-Man, I always have my fuse holders shut when paralleling two pots. I use my voltmeter to see if the secondaries will phase and then I connect the secondaries together hot.

[T-Man]

I mentioned that because we had a crew replace a bad tub and had the splits closed. They assumed the leads were hooked up the same as the last tub was. Trouble was the bad tub was off line and the splits got closed to keep the customers in. They closed those straight across when in reality that split closed cross wise. Back feeding the new tub made double the primary voltage across the cutout.

never the less even if you closed the cutouts first then took voltage readings there would be no zeros (same potential) in that set up.

[Highplains Drifter]

never the less even if you closed the cutouts first then took voltage readings there would be no zeros (same potential) in that set up.


I never have a zero reading, usually one pot is under load and I am adding a new pot to change out the old. I'll pick up up to 10 volts difference and they are the same phase.

[rcdallas]

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[T-Man]

I'm an oldtimer, we used test lamps and they don't light up at 10 volts. Sorry you youngins got all that new fangled test gear. Closing splits we look for zeros in a basic sense. Two 240 and two 0's to close

[Trbl639]

I'm an oldtimer, we used test lamps and they don't light up at 10 volts. Sorry you youngins got all that new fangled test gear. Closing splits we look for zeros in a basic sense. Two 240 and two 0's to close

Test lamp........with a 240V bulb in it!!!!! We didn't have those fancy testers either, and when they started getting them, every time I tried to get one, the Boss said he didn't have the money in his budget!!!!

[Pootnaigle]

Found many an open neutral with that 240 volt bulb in a pigtail socket with homemade leads on it.Put out a lil light in a meter can on a dark night too.

[climbsomemore]

on single phase work you can never make up the phase difference... they will be at least 120 degrees out of wack.

"same phase, the same way" is the fool proof way to parallel to transformers or banks

Now Dallas... we hang a subtractive pot and want to phase it into an existing additive transformer hung up the block. Can that be done?

[lineman2010]

on single phase work you can never make up the phase difference... they will be at least 120 degrees out of wack.

"same phase, the same way" is the fool proof way to parallel to transformers or banks

Now Dallas... we hang a subtractive pot and want to phase it into an existing additive transformer hung up the block. Can that be done?



Sure, you can do it two different ways. You can feed the high side H1 to ground and H2 to the same phase as the first pot then hookup the X bushings in the same manor as the additive pot, or you can feed the high side normal and go X1 to X3 and X3 to X1.