One other important reason for open-delta, that you neglected to mention, is: COST. A lot of utilities (at least here in rural west Texas) will use open-delta systems to supply 3-phase power (typically 120/240v High-leg) to smaller ranches & farms, rural shops, etc., where the majoriy of the load is single-phase, but 3-ph is needed for some motor & machinery loads. Because OD requires ⅓ less resources than traditional 3-phase, it is cheaper to install & maintain: Only two primary HV (7.2/12.5 Kv) conductors are needed (less wire, less insulators, smaller poles), only two pole-mount xfmr's (less hardware, less work/time to install, smaller poles). This amounts to substantial reduction in installed cost for many utility companies, but the customer still gets the 3-ph power needed. Thanks for posting!
One other important reason for open-delta, that you neglected to mention, is: COST.
A lot of utilities (at least here in rural west Texas) will use open-delta systems to supply 3-phase power (typically 120/240v High-leg) to smaller ranches & farms, rural shops, etc., where the majoriy of the load is single-phase, but 3-ph is needed for some motor & machinery loads.
Because OD requires ⅓ less resources than traditional 3-phase, it is cheaper to install & maintain: Only two primary HV (7.2/12.5 Kv) conductors are needed (less wire, less insulators, smaller poles), only two pole-mount xfmr's (less hardware, less work/time to install, smaller poles).
This amounts to substantial reduction in installed cost for many utility companies, but the customer still gets the 3-ph power needed.
Thanks for posting!