Hello all, please pardon the latency of this reply (I just came across the post this evening - 07-23-2010).
I have dealt with many Corner Grounded Delta Systems - with apx. 50% of them being 240V, 40% being 480V, and the remaining 10% being "Various Flavors" (220V, 380V, 600V).
The Line (or Phase - which ever you choose to call it) that is intentionally _GROUNDED_ (Bonded to the GES), is simply the System's Grounded Conductor; and should be treated as all other System Grounded Conductors per NEC Article 250:
- "The System Identified Conductor" White or Gray Color,
- No OCPD in Series - except Multipole Circuit Breakers,
- No Fuseing at Safety Switches / Disconnects (Solid Link in place of Fuse),
- Ground Bonding at the Service / SDS only (unless there are the typical exceptions).
Standard conformity places the Corner Grounded Line / Phase in the "B" Position; so Line "B" = Grounded Conductor.
In Motor Circuits, if there is an OL unit as the final OC device, the Grounded Conductor of this Delta may contain OLs.
Attached below are (3) different Drawings of Delta 3 Phase 3 Wire arrangements;
A: Center Tap Grounded, B: Corner Grounded (Line "B" = Grounded Conductor), and
C: Ungrounded.........................................................
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Fig. 1A: 240V 3 Phase 3 Wire Center Tap Grounded Delta
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Fig. 1B: 240V 3 Phase 3 Wire Corner Grounded "Phase B" Delta
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Fig. 1C: 240V 3 Phase 3 Wire Ungrounded Delta
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These are 240V Systems, but same remains if the System Voltage is 120V, 220V, 380V, 480V or 600V.
BTW, these Schematics are in the Technical Reference section.
Scott