Re- Transformer phasing
Since the primaries are on separate cores, (two transformers) the phasing is irrelevant except that if both transformers are the same phase (start of primary winding to "hot" for example), then the secondaries will be "in phase" for series work - i.e. the "0" winding will be the same secondary wire on both units.
If one transformer is hooked up primary out of phase to the other (start of primary winding of each transformer on different wires), then likewise the secondary windings will be out of phase with one another by approximately 180 degrees.
For practical purposes, hook both transformers up with no load on the secondaries, connect one transformer wire secondary wire to the other, check no load voltage. If no load is in the vicinity of 36 volts or better, you are good. If not, hook together one of the same leads of the connection with the OTHER lead of the second secondary, should now read as above.
Because the units are on separate cores, this will not damage the transformers, if they are on the same core - potential heating of the primary winding can occur with primaries are hooked up out of phase. Also, because the units are on separate cores, the secondary out of phase condition may not be exactly 180 degrees, and thus you would have a small but measurable voltage when the secondaries are hooked up "out of phase"
To verify phasing on a multiple primary transformer, you need a variable voltage source.
leaving secondaries under "NO LOAD" conditions, connect one end of a primary to one end of the second primary. Apply a SMALL voltage (around 10-20 volts) to the combination and note the no load AC voltage on a secondary. Then, disconnecting the primaries, hook the first "one end" to the other end of the second primary. Repeat voltage application.
Odds are that with one configuration you will have a small but repeatable voltage on the secondary (where the two primaries are in phase) and in the other configuration you will have virtually 0 volts on the secondary, (where the two primaries are out of phase).
Finally, and of MOST importance:
BE EXTREMELY CAREFUL when dealing with mains voltages!!! Electrical current moves almost at the speed of light and Mains voltages have sufficient voltage and current capability to be LETHAL!!
ALSO: when dealing with transformer leads, use a method such as brass brads in a board that will allow you to solder the leads into place on your bench, keeping them from flying around to contact you, your equipment or each other! (old transformer engineering trick!)
Hope this helps!
Since the primaries are on separate cores, (two transformers) the phasing is irrelevant except that if both transformers are the same phase (start of primary winding to "hot" for example), then the secondaries will be "in phase" for series work - i.e. the "0" winding will be the same secondary wire on both units.
If one transformer is hooked up primary out of phase to the other (start of primary winding of each transformer on different wires), then likewise the secondary windings will be out of phase with one another by approximately 180 degrees.
For practical purposes, hook both transformers up with no load on the secondaries, connect one transformer wire secondary wire to the other, check no load voltage. If no load is in the vicinity of 36 volts or better, you are good. If not, hook together one of the same leads of the connection with the OTHER lead of the second secondary, should now read as above.
Because the units are on separate cores, this will not damage the transformers, if they are on the same core - potential heating of the primary winding can occur with primaries are hooked up out of phase. Also, because the units are on separate cores, the secondary out of phase condition may not be exactly 180 degrees, and thus you would have a small but measurable voltage when the secondaries are hooked up "out of phase"
To verify phasing on a multiple primary transformer, you need a variable voltage source.
leaving secondaries under "NO LOAD" conditions, connect one end of a primary to one end of the second primary. Apply a SMALL voltage (around 10-20 volts) to the combination and note the no load AC voltage on a secondary. Then, disconnecting the primaries, hook the first "one end" to the other end of the second primary. Repeat voltage application.
Odds are that with one configuration you will have a small but repeatable voltage on the secondary (where the two primaries are in phase) and in the other configuration you will have virtually 0 volts on the secondary, (where the two primaries are out of phase).
Finally, and of MOST importance:
BE EXTREMELY CAREFUL when dealing with mains voltages!!! Electrical current moves almost at the speed of light and Mains voltages have sufficient voltage and current capability to be LETHAL!!
ALSO: when dealing with transformer leads, use a method such as brass brads in a board that will allow you to solder the leads into place on your bench, keeping them from flying around to contact you, your equipment or each other! (old transformer engineering trick!)
Hope this helps!