If the automatic controls fail a manual start switch

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equipment loads, to keep the remaining generator within its kw rating. If the automatic controls fail, a manual start switch will be provided to override the automatic start of the engine-generator sets so they can be cranked, synchronized and connected on the emergency bus. 3.10 Return to Normal Power Source . Thirty minutes following the return of a stable normal power supply, both emergency system loads and equipment system loads will be automatically transferred to the normal power source. An automatic timer, having an adjustable time range of from 2 to 30 minutes (set at 30 minutes), will be provided to this transfer. Following transfer of the loads, generator sets will continue to run, unloaded, for a period of 15 minutes before shutdown, after which the controls will automatically reset for a new cycle. A manual start switch will override the automatic start of engine generator sets so they can be manually cranked, synchronized, and connected to the emergency bus, if automatic controls fail. Additional manual controls will be provided as indicated elsewhere in this section. 3.11 Automatic Transfer Switches (ATS) . All ATSs will be double-throw with draw-out construction. Contacts will have viewing ports for ease of contact inspection. ATSs shall have been UL tested with the main up-stream breaker to assure coordinated withstand compatibility between the ATS and the interruption time of the breakers. Circuit breaker type transfer switches are not acceptable. Each ATS will have indicator lights to identify Normal Power (green in color) and Emergency Power (red in color). All ATSs will be equipped with a load break by-pass isolation switch (The by-pass isolation switch can be initiated with not more than two movements of the hand to either position regardless of the position or condition of the ATS.) to maintain normal or emergency power while the ATS is being repaired or maintained. Load bypass to the ATS's connected source will be achieved with either no load interruption, or a load interruption of not more than 10 (CYCLES) hertz. ATSs feeding high efficiency motors rated 25 horsepower or larger will be provided with an in-phase monitor to prevent an out-of-phase transfer. The in- phase transfer will be achieved without control of the frequency of either power source to prevent excessive motor in-rush current. Use of closed-transition switching for © J. Paul Guyer 2010 16
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facilitating essential system testing requires special justification and approval. The by- pass isolation switch for the ATSs serving nonessential equipment can be optional. 3.11.1 ATS and Bypass/Isolation Switch Location. For new inpatient facilities, the ATS and BP/IS equipment shall be in a separate CMU 2-hour fire rated room with direct access from the normal main power equipment room and the alternate power source equipment room. 3.12 ATS and Bypass/Isolation Switch (BP/IS) Testing . Laboratory testing will be conducted on the ATS and BP/IS to be supplied for this facility, or shall have been completed on a previous, randomly selected standard production ATS and BP/IS unit having the same model and capacity as the ATS and BP/IS specified. The overload,
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