Trace T240 Autotransformer.

littleharbor2

Trying to figure out how useful this would be. On page 8 of the manual It appears to put out two legs to the 240 load. I see no mention of split phase output. My questions are, is the 240 vac output a single phase and only useful for a limited amount of items? Can it be wired into a split phase 120/240 vac. power panel?

T240 Manual 975-0001-01-02 Rev. B (unboundsolar.com)

BB.

From your link:

This should do it for you...

Note, this assumes a TSW/PSW inverter with Neutral+Ground bond (either inside the inverter or inside your "main panel"--You may need to confirm where).

The Ground Bonded Neutral is not needed for function--But follows NEC and is "required" for safety (long story about "floating" power systems needing Breakers on all connections, vs ground bonded neutral needing breakers on L1 and L2, none needed on neutral).

For MSW inverters (modified sine/square wave), transformers don't really "like" that wave form (can cause transformers to run hot/waste power). Also, almost all MSW inverters cannot have a ground bonded neutral and a ground bonded negative (or positive) battery bus--That will "short out" the MSW inverter and let out the magic smoke (MSW inverters do not have electrically isolated AC output; TSW/PSW inverters have electrically isolated AC output and support N+G bonding).

-Bill

littleharbor2

BB. said:

From your link:

This should do it for you...

Note, this assumes a TSW/PSW inverter with Neutral+Ground bond (either inside the inverter or inside your "main panel"--You may need to confirm where).

The Ground Bonded Neutral is not needed for function--But follows NEC and is "required" for safety (long story about "floating" power systems needing Breakers on all connections, vs ground bonded neutral needing breakers on L1 and L2, none needed on neutral).

For MSW inverters (modified sine/square wave), transformers don't really "like" that wave form (can cause transformers to run hot/waste power). Also, almost all MSW inverters cannot have a ground bonded neutral and a ground bonded negative (or positive) battery bus--That will "short out" the MSW inverter and let out the magic smoke (MSW inverters do not have electrically isolated AC output; TSW/PSW inverters have electrically isolated AC output and support N+G bonding).

-Bill

Bill, thanks for your fast reply.. I would be using my Trace SW 4024.
 Maybe I cant see the forest for the trees, so to speak but I still don't see any terminology pointing to split phase output.

Dave Angelini

The black box labeled 240 VAC LOAD IN BILL'S diagram ?  Remember happy hour is not suppose to start before 5pm

littleharbor2

Dave Angelini said:

The black box labeled 240 VAC LOAD IN BILL'S diagram ?  Remember happy hour is not suppose to start before 5pm

No happy hour. Just got up from a siesta. Going to jump in the 90 degree sea fo a 1/2 hour or so. 
So is there such a thing as 240 single phase using two hot legs not 180 degrees out of phase? I guess not. I kind of figured well pumps and such might be single phase. There is a well pump wiring diagram in the manual on page 9.

BB.

Think of each transformer winding as being a pair of 1.5 volt batteries connected in series... L1 to N is +1.5 volts, N to L2 is +1.5 volts again..with the two batteries in series you get 3.0 volts

So see the "out of phase". Put the Meter black lead on Neutral (center tap). Measure Red lead to L1, you get -1.5 volts. Measure Red lead to L2, you get +1.5 volts... They are 180 out of phase (OK, DC does not really have phase, but you can see that L1 and L2, relatively to Neutral, are going in "opposite" directions (180 degrees out of phase).

The technical term is 120/240 VAC 60 Hz "Split Phase" power... Split phase power is still single phase.

To have multiple phase power, the angle between the two (or more) phases need to be shifted to non 0 / non 180 degrees. For example, 3 phase power is 120 degrees phase shift between phases. And with multiple phases, such as 3 phase, when you connect them to fields in a motor, you get a "rotating" magnetic field. Split phase power is a single non-rotating field that is flipping North/South.

https://en.wikipedia.org/wiki/Three-phase_electric_power (example of first multi-phase motor--2 phase at beginning--Not split phase).

https://en.wikipedia.org/wiki/Split-phase_electric_power

Note that the transformers are "polarity sensitive"... They will put a DOT on each winding lead to indicated phasing/polarity:

https://www.quora.com/What-is-the-dot-convention-of-a-transformer


Does this help?

-Bill

Dave Angelini

Ah, I see where he is getting mixed up! Eureka !!!   A beer before Siesta

This may help you, the well pump is not going to get a neutral connection, it will just see the (2) 120 vac legs as 240vac.

littleharbor2

Yes, Eureka it is!! That explains it perfectly. Thank you again Bill and Dave. At my ripe old age it sure feels good to learn stuff still. I'm going to print this page out and memorize it word for word.
 I think I'll have a beer now Dave. 

Ralph Day

I had at 240 supplying 240v to my submersible water pump with an sw4048 inverter (120vac).  The pressure switch when "on'" would put power to the t240 and the pump, at the same time.  I once saw the display on the inverter hit 45amps (as high as it would display i beleive).  The old CRT type colour tv would go black and white with the display shrinking in a couple of inches from the edges of the picture tube.

Who knows how much draw the pump and t240 actually drew on startup.  If you can, I'd suggest having a delay between t240 energizing and the load engaging.  

The tv eventually died.  The inverter developed a fault (ac out relay I think) and was replaced with an Outback FXR3648

Saggys

I am using a T220 on the load side of my pressure switch to power our grundfos sq series well pump and it has been working great for the last year or so.
The T240 requires 14 watt hours just to be energized, so less time on, more efficient.  The T220 is Trace's earlier autotransformer, which is slightly smaller than the T240.