Automatic transfer switch

The manual-automatic transfer switch is a five position switch that alters the mode of operation. 

Start-up of the exhaust ventilation system and critical equipment must be sequenced to prevent a hazardous condition. In addition, the starting of the supply air handling unit and the exhaust fan services each room shall initiate simultaneously to avoid placing the room under positive pressure. Automatic transfer switching will be used. 

Important loads can be connected to redundant feeder circuit breakers, one on each side of the double-ended switchgear, by connecting the load sides of the circuit breakers together with a feeder cable. This approach should be used with caution. Another approach is to connect the redundant feeder circuit breakers to a time-delayed automatic transfer switch. 

The engine-generator shown in Fig. 10.175 is the classic standby power system. An automatic transfer switch monitors the AC voltage coming from the utility company line for power failure conditions. 

FIGURE 10.176 The dual utility feeder system of AC power loss protection. An automatic transfer switch changes the load from the main utility line to the standby line in the event of a power interruption. 

Static Automatic Transfer Switches. Static automatic transfer switches provide an alternative to full UPS protection if a facility is served by two synchronized utihty power feeds. When the power supply to one feed is interrupted, the load is automatically transferred to the second power feed without affecting equipment. 

Automatic transfer switch (ATS) An electric switching device that alternately connects the load to the normal or emergency power source as required without operator involvement. It may also include controls that start and stop the engine-generator set, monitor voltage and frequency of both power sources, and perform other tuning and logic functions. See also nonautomatic transfer switch. 

Option A Engine generator with battery bank Cost assumptions Engine Generator Automatic transfer switch Fuel storage tank and monitor Battery stack Installation Fuel service Annual maintenance... 

In general, automatic transfer switches are provided for code-required emergency loads, and manual transfer switches are provided to change from a main to a standby fen or pump, or to change from a normal to redundant power source. (See Fig. 4.)... 

The Recirculation Pump Emergency Diesel Generator System included several auxiliary components (not the diesel generator units themselves) which were seismically qualified by testing for the restart program. Examples of these equipment items are relays, the automatic transfer switch, disconnect switches, and transformers. 

The electric power systems for the production reactors at Savannah River include severer special features such as automatic shedding upon degraded frequency, a special Containment Substation, and extensive use of automatic transfer switches which provide alternate power sources for important loads. 

ECS system possesses an automatic transfer switch that activates valves on two separate ECS addition lines thus, its failure could render two ECS lines inoperative. The long operational history at SRS provides a credible data... 

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