Replacing a Delta Distribution transformer feeding an existing Delta load by a Y-Y transformer
Replacing a Delta Distribution transformer feeding an existing Delta load by a Y-Y transformer
(OP)
Our distribution grid is a Y-Y multigrounded system, so we plan to replace the few existing and old delta transformers feeding delta loads with standard Grounded Y-Y distribution transformers (500kVA to 3000kVA), with the star points solidly grounded on both side; a three wire circuit will feed the delta load.
Is there any problem to anticipate? How will the system behave under fault conditions (eg L-G, L-L-G)? any fire danger?
Any good suggestion as how to tackle this situation (feeding delta load with a Y-Y transformer). Any good paper or book on this?
Thanks!
Is there any problem to anticipate? How will the system behave under fault conditions (eg L-G, L-L-G)? any fire danger?
Any good suggestion as how to tackle this situation (feeding delta load with a Y-Y transformer). Any good paper or book on this?
Thanks!






RE: Replacing a Delta Distribution transformer feeding an existing Delta load by a Y-Y transformer
RE: Replacing a Delta Distribution transformer feeding an existing Delta load by a Y-Y transformer
For ungrounded delta, you have the risk that there may be an existing persistent ground fault. It needs to be repaired prior to change-over. I second the suggestion to talk to every customer. Knowledgeable customers will know what is needed, some may need help preparing.
RE: Replacing a Delta Distribution transformer feeding an existing Delta load by a Y-Y transformer
If you are going from 440 V to 480 V, most of the customers equipment will be fine but it will be well to check all existing equipment for possible issues.
If you are going from 230 V to 120:208 Volts some customers equipment may not perform adequately.
If you are going from 240 V to 120:208 Volts some customers equipment may not perform adequately.
You may consider providing small voltage boosting autotransformers for problem equipment.
Bill
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"Why not the best?"
Jimmy Carter
RE: Replacing a Delta Distribution transformer feeding an existing Delta load by a Y-Y transformer