transformer???

[enrique santiago]

i went to a call this mornin to check some tings and after mi service i start to take some info about the place and the service....this is mi cuestion.....what type of service is feeding this main service????
the panel say 3 phases 3 wires
the phase A vs. ground 240 volts
phase B vs. ground 0 v
phase c vs. ground 240 v
phase a vs. b 240 v
phase a vs. c 240 v
phase b vs. c 240 volts

 

[frenchelectrican]

Re: transformer???

becarefull with this one a good chace that you have corner ground delta service or straght delta but what you mention that b phase to ground is 0 volts can happend two thing is : one is corner ground service the second thing that you have "open" delta service a quick hint check the meter box and service drop to post then count the cans on post it should be 3 for both delta or wye servce otherwise if you see 2 cans mean open delta service ( few power compaines still have it not much any more ) but i am more leaning to open delta service but did you check the box when you reading the voltage it should be a marking like colour or something like that

merci marc

 

[enrique santiago]

Re: transformer???

the service is underground and really i did not take to much time to check deeper, but the service i s feeding a transformer delta 240 star 120/208 , and i check the transf. and the voltage was ok 120 phases vs. ground and 208 betwen

 

[jim dungar]

Re: transformer???

Enrique,

You have a grounded B-phase system. It does not make any difference if it is fed by a Closed or Open delta transformer bank.

My only concern is if the system was intended to be grounded, or do you have a fault to ground?

Intentionally grounded systems can usually be determine by:
bonding of phase to ground at service entrance
the use of two-pole switches, breakers, and bus bars
an identified grounded conductor in the system

 

[bennie]

Re: transformer???

This configuration is usually done at remote water well locations. Two phase legs and the MGN are connected open wye/open delta to two 240 volt pots. This provides 240 three phase for the pump.

A small 240/120 transformer is connected for lights and a receptacle.

This setup saves one long power line and a transformer.

 

[scott thompson]

Re: transformer???

Bennie,

Nice to see 'Ya again!!! How's everything been lately?

Re: MGN distribution; I created some Schematics of MGN Distribution systems, and posted them in the ECN Technical Reference area.
Another one of the Moderators at ECN (Paul, Moderates the Non-US Electrical Systems area) contributed several MGN system schematics, which are used widely in UK.

Paul drew them in a graphics app., sent them to Nick - who redrew them with AutoCAD 2K, then sent to me for rasterizing and uploading.
Sure got around, didn't they?!

Scott35.

P.S. The system in question sounds like a 3? 3Wire Corner (?B) Grounded Delta, mostly due to the topic starter's location being in California and the 240 VAC L-L + L-G ( 0 VAC for B to ground). Haven't seen any MGN Open Wye setups around here yet. Saw many in Vegas and Oregon. Instead, we have a Gazzillion Open Delta Vee setups spread everywhere.

 

[enrique santiago]

Re: transformer???

thanks a lot
yours coments really help me

 

[mikeames]

Re: transformer???

Hi benny.

This is the Benny from Oregon right?