Grounding B Phase

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bgtires said:
Why do you intentually take a phase on a Delta to Delta system and put right to ground?
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When there is no neutral, it is common to ground a phase. With the exception of not fusing it (3-phase breakers are okay), you treat it just like any 3-phase Delta system, but you bond and color it like any grounded conductor.
 
bgtires said:
Why do you intentually take a phase on a Delta to Delta system and put right to ground?
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One major reason is to provide a stable voltage reference during fault conditions.
 
Look at 240.22. Fuses are not permitted in a Grounded B Phase. Using equip that "looks" like single phase but is rated for 240V 3 phase grounded B Phase is commonly used when fuses are involved.
 
bgtires said:
We are using fuses. The transformer has a breaker in it, but from there we go to a fuse disconnect.
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A 3-phase breaker is okay because the internal common-trip and tie handle on the breaker open all poles simultaneously, whereas a fused disconnect can open only one pole, so a non-fused link (dummy fuse) must be used in the grounded pole.
 
sandsnow said:
Using equip that "looks" like single phase but is rated for 240V 3 phase grounded B Phase ...
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The difference is: the 2-pole breakers are 240V only (not the common slash rated 120/240V ones) and they are specifically listed for grounded B phase applications.
 
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