Distribution Transformer Bank Configuration
Distribution Transformer Bank Configuration
(OP)
All,
Good Day!
I would like to inquire what Transformer Bank Configuration is currently practiced by your utility for three-phase distribution to customers.
For example, we are using Y - delta(center-tapped) but are planning to change it since we are encountering voltage problems during single-phasing.
Thanks...
Good Day!
I would like to inquire what Transformer Bank Configuration is currently practiced by your utility for three-phase distribution to customers.
For example, we are using Y - delta(center-tapped) but are planning to change it since we are encountering voltage problems during single-phasing.
Thanks...






RE: Distribution Transformer Bank Configuration
Common voltages in North America are 120/208V, 277/480V and in Canada, 347/600V.
Three phase transformers may be delta:wye and single phase banks are most often wye:wye.
Bill
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"Why not the best?"
Jimmy Carter
RE: Distribution Transformer Bank Configuration
Changing is rather difficult because except for the 480 services, configuration change would cause a change in the service voltage.
Not sure how you can avoid a voltage problem during single phasing, since by definition you have a voltage going to zero for that condition. Phase loss protection is always advised for three phase machinery.
RE: Distribution Transformer Bank Configuration
Does your utility use DELTA-wye(grounded) using single-phase transformers? It's relatively costly but would just want to know...
http://www.powerqualityworld.com
RE: Distribution Transformer Bank Configuration
Ironically, we are not worried with phase loss during single-phasing but with voltage swells. We have made actual tests using additive single-phase transformers and have confirmed that overvoltages/swells occur especially with unbalance loading.
Obviously, WYE(G)-wye(g) is the most stable configuration in terms of voltage but we're a bit worried (should we?) about harmonics and SLG protection issues.
http://www.powerqualityworld.com
RE: Distribution Transformer Bank Configuration
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Distribution Transformer Bank Configuration
Hey waross,you're a utility guy right? (based on how you answered)
Any bad experience with the WYE(G)-wye(g) bank? Voltage wise, it is very stable. But how about other issues such as harmonics and SLG fault protection concerns?
Thanks...
http://www.powerqualityworld.com
RE: Distribution Transformer Bank Configuration
When I started with the utility we had some serious issues with wye:delta with a four wire primary connection. This was a part of the world where the only wye:delta connection used was a four wire primary connection. On the mainland served by the Government owned utility it was interesting to drive around and observe the wye:delta banks. Most had a fuse blown and one cutout hanging down and were operating open delta with one transformer idling on the secondary connection. It took several years to have the industrial users changed from wye:delta to wye:wye to eliminate these issues.
We had a non-symmetrical sub-sea feed to a small island that caused voltage issues but no issues that we knew of as a result of the transformer connections.
All our distribution protection was by fuses, nothing sophisticated.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Distribution Transformer Bank Configuration
Thanks for the info...
It's of big help as I'm currently inquiring other utilities with regards to their common practice on transformer banking...
We are on the verge of changing our WYE(FLOAT)-delta(center-tapped) into a less problematic transformer configuration with WYE(G)-wye(g) and DELTA-wye(g) as the likely candidates.
To other forumers, please do not hesitate on sharing your experiences and I would really appreciate it.
Thanks...
http://www.powerqualityworld.com