Needing 208V on a High leg delta service

J

Jimbobwey

Member
Location
Illinois
Occupation
Electrician
I've got 2 T111683 transformers that should be able to accomplish this. Looking for worrying help.

Service is High leg delta
Phase A - neutral 120
Phase B - neutral 120
Phase C - neutral 208
245 between all phases

Equipment needs
3 Phase 208-230V 12kW

Thanks in advance
 
Jimbobwey said:
I've got 2 T111683 transformers that should be able to accomplish this. Looking for worrying help.

Service is High leg delta
Phase A - neutral 120
Phase B - neutral 120
Phase C - neutral 208
245 between all phases

Equipment needs
3 Phase 208-230V 12kW

Thanks in advance
Click to expand...
Seems like you should just connect it directly to the supply. Why do you need a transformer?
 
Your math for the voltages does not add up, but that is not important, your system is a nominal 240/120V 3ph 4wire (often called a high-leg).

If you need 208V 3ph, you will need a transformer.
 
Last edited:
Jimbobwey said:
The equipment max voltage is 235
Click to expand...
Do you need a neutral? Does your equipment have L-G connected components like filters?

You may be able to use a simple buck-boost transformer arrangement with a nominal 10% voltage change.
 
A couple of 0.75 kVA buck configured transformers would give you plenty of room if you truly need to be at less than 235 volts and don't require a neutral.
 
CoolWill said:
A couple of 0.75 kVA buck configured transformers would give you plenty of room if you truly need to be at less than 235 volts and don't require a neutral.
Click to expand...
This is correct, no neutral needed.
I have 2) T111683 transformers just looking for how they get connected correctly.
 
1743087314811.jpeg
In your case, you would apply the 240v to the "out" terminals and connect your load to the "in" terminals.
 
See https://hubbellcdn.com/catalogfull/AE_CAT_7_001.pdf

Look at page 17 for connections. You get to pick, connection CC will take 245V down to 233V; connection EE will take 245V down to 221V. The T111683 has enough capacity to work for you in either configuration.

How strict is the 235V limit? Normally a 240V service (which you have) is expected to work with equipment with a nominal 230V utilization voltage. But if you really have a hard 235V limit, I would use connection EE.
 
winnie said:
See https://hubbellcdn.com/catalogfull/AE_CAT_7_001.pdf

Look at page 17 for connections. You get to pick, connection CC will take 245V down to 233V; connection EE will take 245V down to 221V. The T111683 has enough capacity to work for you in either configuration.

How strict is the 235V limit? Normally a 240V service (which you have) is expected to work with equipment with a nominal 230V utilization voltage. But if you really have a hard 235V limit, I would use connection EE.
Click to expand...
I was thinking the same but I don't have much experience with these setups. With the name plate saying max 235 I didn't want to take a chance and smoke the unit. Apriciate the help.
 
winnie said:
You get to pick, connection CC will take 245V down to 233V;
Click to expand...
Which is the same as the diagram I posted above, but with in and out properly labeled.

winnie said:
connection EE will take 245V down to 221V.
Click to expand...
The only difference being the LV windings are wired in series instead of in parallel.

When boosting, this increases the boost; when bucking, this increases the buck.

winnie said:
Normally a 240V service (which you have) is expected to work with equipment with a nominal 230V utilization voltage. But if you really have a hard 235V limit, I would use connection EE.
Click to expand...
I agree with these statements.
 
You must log in or register to reply here.
Top