I have six identical transformers (same mfr, same number) 240v in and (depending on wiring of primary coils) 20-55v out. The secondary consists of two identical--not center tapped--coils. The 20-55v value is per coil, that is the secondary coils are not connected in series. Each transformer weighs 23 pounds. I want to use these transformers in a combined configuration for a rectified welding power source (constant voltage). My questions concern the best way to do this.
1) I have just assumed that the primaries should be connected in parallel, but what would happen if they were connected in series? Is there any advantage of one method over the other?
2) Turning to the secondaries, consider first, please, the case of a single transformer. The two secondary coils could be paralleled and the output rectified using a 4 diode FWB. Would it also be possible to connect the end of one coil to the beginning of the other and, using this connection as a center tap, rectify with a 2-diode center-tapped FWB? Paralleling the secondaries seems superior because all the copper is in play every half cycle, but in the center-tapped configuration half the copper gets to rest (cool) every half cycle. Does one configuration have higher amperage capacity? Both would deliver the same voltage, correct?
3a) However the secondaries of the individual transformers were configured, I would then parallel the outputs of the six transformers.
3b) If a center-tapped FWB design was used, I assume I'd connect all six center taps, all six dotted secondary ends and all six un-dotted ends. Then on to the two bridge diodes.
4) Would the mounting of the transformers have any effect on their magnetic relationship and regulation? My plan is to make a rack for them leaving an inch or so of cooling space all around each transformer.
In terms of cooling several individual transformers might actually be better for a constant voltage power supply than one big transformer. Large transformers in some welding machines, even CV machines, sometimes have air gaps between winding layers for cooling; it seems that this would degrade coupling and regulation. Each of my six have the general shape of a shoe box, with just a hint of winding showing at each end--the windings are buried in core, which makes me think these transformers will have excellent regulation.
One last question: If I were to use one of the secondary coils in a buck/boost configuration with the primary, that wouldn't compromise the isolation properties of the transformer, would it?
Thanks in advance.
1) I have just assumed that the primaries should be connected in parallel, but what would happen if they were connected in series? Is there any advantage of one method over the other?
2) Turning to the secondaries, consider first, please, the case of a single transformer. The two secondary coils could be paralleled and the output rectified using a 4 diode FWB. Would it also be possible to connect the end of one coil to the beginning of the other and, using this connection as a center tap, rectify with a 2-diode center-tapped FWB? Paralleling the secondaries seems superior because all the copper is in play every half cycle, but in the center-tapped configuration half the copper gets to rest (cool) every half cycle. Does one configuration have higher amperage capacity? Both would deliver the same voltage, correct?
3a) However the secondaries of the individual transformers were configured, I would then parallel the outputs of the six transformers.
3b) If a center-tapped FWB design was used, I assume I'd connect all six center taps, all six dotted secondary ends and all six un-dotted ends. Then on to the two bridge diodes.
4) Would the mounting of the transformers have any effect on their magnetic relationship and regulation? My plan is to make a rack for them leaving an inch or so of cooling space all around each transformer.
In terms of cooling several individual transformers might actually be better for a constant voltage power supply than one big transformer. Large transformers in some welding machines, even CV machines, sometimes have air gaps between winding layers for cooling; it seems that this would degrade coupling and regulation. Each of my six have the general shape of a shoe box, with just a hint of winding showing at each end--the windings are buried in core, which makes me think these transformers will have excellent regulation.
One last question: If I were to use one of the secondary coils in a buck/boost configuration with the primary, that wouldn't compromise the isolation properties of the transformer, would it?
Thanks in advance.
