Three Phase 4 Wire Delta

Showing different voltages of a three phase 4 wire Delta Transformer, and calculating the high leg voltage.

Feel like buying Chris a coffee? Think of it as SchulerRuler fueler!

[jonnygigg]

Another really good video, explaining something I knew about before but didn't quite understand. Such a good teacher!

[mdslax]

Probably the best explanation I have seen yet! Great job

[matthewmattie]

One of the chillest guys I've ever worked with right here.

[DanBurgaud]

In my neighborhood, this High Leg 3Phase is supplied by the electric utility company using 2transformers (not three as suggested in the schematic above).
The 1st transformer is a center tapped transformer delivering B, N, C. The 2nd Transformer is wired as A, N and is perpendicular to B and C phase.

[sethtaylor]

At First Energy we called the middle pot (that's 120/240) the Lighting Pot. Smallest config wud be two 25 KVA wing pots and a 50 KVA lighting pot. Usually the three phase load is smaller than the 120/240 load in commercial customer. On occasion, all three would be 25 KVA minimum.

[nbultman_art]

I kept lapsing into distraction trying to figure out HOW YOU'RE WRITING BACKWARDS ON THIS BOARD. Or are you mirroring your body to be behind the glass you're writing on, when in reality, you're in front? I'M SO CONFUSED

[alexanderacosta]

Thank you. I really understand now high leg with your video.

[Sparky-wwre]

Many might not be aware, but it is possible to have a 4 wire delta at 480 volts. You'd have 240v L-N, 415v high leg - N, and 480 L-L. I've heard of them a time or two, they are super rare and kinda pointless, because if you had a 480 volt system and needed to run 240 volt equipment normally you'd have a 277/480Y system and use a 480 to 240 transformer. Wye systems are the most common because load balancing is easier when supplying single phase equipment. Delta systems are really only practical when most of your loads are 3 phase, also it's easy to accidentally connect 120 volt equipment to the high leg and destroy stuff. For these reasons 4 wire delta systems are rarely used in new installations.

[chikitin]

What would happen if you tap another coil in the 4 wire delta, i mean a 5 wire delta. Will it cause a failure? Or still working?

[khactamtran]

sorry, what happen if the phase C short to ground. Is the system still operate normal or relay will be trip?

[wildness]

Would it be possible to create a high leg wye system? With two 120v windings and one 208 volt winding all center grounded but phased so that they could basically mimic high leg delta but actually be wye derived?

I'm asking this because I use inverter derived 3 phase where each leg is digitally controlled from a seperate inverter, for offgrid solar applications. I'm wondering if it would be possible to use 2 120v inverters and one 208v inverter to mimic a high leg delta system.

[atomicdmt]

I am design a commerical solar PV system. Best solution? We were going to stagger 6 1ph the need for neutral is very likey going to be a conflict. Solutions? THANKS

[electrotech]

Did you ever upload the next video? This one was great.

[ronbass]

Can you feed the primary voltage into the secondary of transformer and get the same change

[adambachert]

Could you do a video similar to this on a solid or "corner" ground system?

[charlesgault]

I know that the hi leg setup is used in situations where both single and three phase voltages are in use but is there any use for the 208v between phase A and the neutral wire?

[zakattack]

At 3:29 did you intend to write Va-b? Not Va-n?

[lkingofledimb]

hmmm that fairly eazy… so you have any videos that describe the basic principles of a single line diagram.. have some yough guys in the team that I put together and I found out that they are visual learners... THESE youngh men are of the new era.. so they love being on there phone a lot, so instead of them watching nonsense during break imma make them watch your videos... they will hate me at first but over time they will thank me.... you see what I mean?? thanks in advance SIr... love your work.... god bless.

[sheikhawais]

Your way of explanation is really great! May anyone please answer here what would be the reduced capacity (kVA) if we have only open delta at primary and not at secondary. We've D-Yn (11kV to 415V) transformer. Let's have initially rated power of 30kVA. Thanks in anticipation

[matthewellis]

It seems that you need to be left handed to be able to write in reverse on a piece of glass..lol.

Is that what he is doing?