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Closed Transition ATS’s John J. Stark Marketing Services Coordinator, Russelectric Inc. Closed Transition Transfer of non-utility generator, re-transfer and generator test Cogeneration Peak Shaving Curtailable Rate Structure Distributed Generation.
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Closed Transition ATS’s John J. StarkMarketing Services Coordinator, Russelectric Inc.
Closed Transition Transfer of non-utility generator, re-transfer and generator test Cogeneration Peak Shaving Curtailable Rate Structure Distributed Generation Why Operate in Parallel with the Utility?
Types of Operational Modes • Open Transition • Closed Transition
First let’s talk about open transition mode An open transition mode of operation is a method of transferring a load between two sources with an interruption of power during transfer.
Open transition ATS N N N Motor #1 drives the normal source contacts Open. L L M1 L M2 Motor #2 then drives the emergency source contacts closed E E E This is all done with very reliable mechanical interlocking and does not require an elaborate electrical interlocking design. The load source is disconnected for an adjustable period to allow regenerative power to decay
Closed Transition Mode A closed transition mode of operation is a method of either: 1) Transferring a facility’s load between the utility and generator or 2) operating a generator in continuous parallel with the utility service, without an interruption of service.
Utility Concerns • Reliability and quality of utility power to other customers • Safety and protection of utility service personnel • Protection of utility equipment
Passive Momentary utility parallel operation 100ms or less Type of Parallel Operation
Closed transition ATS N N N S1 S2 L L L E E E Operator #1 drives the normal source contacts open The load source is connected to both sources momentarily Operator #2 drives the emergency source contacts closed Closed Transition Operation
Closed Transition Transfer Switches Closed Transition Transfer Switches • Advantages • No interruption of power for load test and • return to utility as well as peak shave operation • Fast transfer operation
Closed Transition Transfer Switches Closed Transition Transfer Switches Disadvantages • No phase lock synchronizing • No Protective relays • No mechanical interlock, thus no safe manual operation • Lacks true load test function • Higher fault current requirements
Sophisticated Controls and Safety Features Full 3-Phase over and under voltage and frequency sensing on both normal and emergency sources. Protection against running over 100 msecs: Signals to operators Fail to Transfer Function Provides trip signals to the generator or utility breakers.