practicable and economical. Double-ended unit substation distribution systems
will be designed for hospitals, medical centers and specially designated
facilities. Each transformer in the double-ended unit substation will be
sized to serve approximately 60-70 percent of the substation demand load
(linear and nonlinear) before forced air cooling is initiated and 100% of
demand load with forced air cooling initiated and will be impedance matched.
All double-ended unit substations will have coordinated surge and fault
protection. System protection will be selective.
NORMAL AMBULATORY AND CLINIC SOURCE. All other health care
facilities will be served by a single-ended substation distribution system
with coordinated surge and fault protection. The primary service feeder will
be designed to carry full demand plus 20 percent spare load growth capacity.