Closed Transition ATSs John J. Stark Marketing Services Coordinator, Russelectric Inc.

Closed Transition ATS’sClosed Transition ATS’sJohn J. Stark

Marketing Services Coordinator, Russelectric Inc.

Why Operate in Parallel with the Utility?Why Operate in Parallel with the Utility?

• Closed Transition Transfer of non-utility Closed Transition Transfer of non-utility generator, re-transfer and generator testgenerator, re-transfer and generator test

• CogenerationCogeneration• Peak ShavingPeak Shaving• Curtailable Rate StructureCurtailable Rate Structure• Distributed GenerationDistributed Generation

Types of Operational ModesTypes of Operational Modes

• Open Transition Open Transition

• Closed TransitionClosed Transition

First let’s talk about open transition modeFirst let’s talk about open transition mode

An open transition mode of operation is a An open transition mode of operation is a method of transferring a load between two method of transferring a load between two sources with an interruption of power duringsources with an interruption of power during

transfer. transfer.

N

E

LL

N

E

The load source The load source is disconnected is disconnected for an for an adjustable adjustable period to allow period to allow regenerative regenerative power to decaypower to decay

Motor #1Motor #1drives thedrives thenormal source normal source contactscontactsOpen.Open.

M1

Motor #2Motor #2then drives the then drives the emergencyemergencysource source contactscontactsclosedclosed

M2

N

E

L

This is all done This is all done with very reliable with very reliable mechanical mechanical interlocking and interlocking and does not require does not require an elaborate an elaborate electrical electrical interlocking interlocking design.design.

Open transition ATSOpen transition ATS

Closed Transition ModeClosed Transition Mode

A closed transition mode of operation is a A closed transition mode of operation is a method of either:method of either:

1) Transferring a facility’s load between the 1) Transferring a facility’s load between the utility and generator or 2) operating a generator utility and generator or 2) operating a generator in continuous parallel with the utility service, in continuous parallel with the utility service, withoutwithout an interruption of service. an interruption of service.

Utility ConcernsUtility Concerns

• Reliability and quality of utility power to other Reliability and quality of utility power to other customerscustomers

• Safety and protection of utility service personnelSafety and protection of utility service personnel• Protection of utility equipmentProtection of utility equipment

Type of Parallel OperationType of Parallel Operation

• Passive Momentary utility parallel Passive Momentary utility parallel operationoperation– 100ms or less100ms or less

Closed Closed Transition Transition OperationOperation

L

N

E

The load The load source is source is connected to connected to both sources both sources momentarilymomentarily

Operator #1Operator #1drives thedrives thenormal normal source source contactscontactsopenopen

Operator #2Operator #2drives the drives the emergencyemergencysource source contactscontactsclosedclosed

L

N

E

L

N

E

S2S1

Closed transition ATSClosed transition ATS

Closed Transition Closed Transition Transfer SwitchesTransfer SwitchesClosed Transition Closed Transition Transfer SwitchesTransfer Switches

AdvantagesAdvantages•No interruption of power for load test and No interruption of power for load test and return to utility as well as peak shave operationreturn to utility as well as peak shave operation•Fast transfer operationFast transfer operation

Closed Transition Closed Transition Transfer SwitchesTransfer SwitchesClosed Transition Closed Transition Transfer SwitchesTransfer Switches

DisadvantagesDisadvantages

•No phase lock synchronizingNo phase lock synchronizing•No Protective relaysNo Protective relays•No mechanical interlock, thus no safe manual operationNo mechanical interlock, thus no safe manual operation•Lacks true load test functionLacks true load test function•Higher fault current requirementsHigher fault current requirements

Full 3-Phase over and under Full 3-Phase over and under voltage and frequencyvoltage and frequencysensing on both normal andsensing on both normal andemergency sources.emergency sources.

Protection against running overProtection against running over100 msecs:100 msecs:

Signals to operatorsSignals to operators

Fail to Transfer Function Fail to Transfer Function Provides trip signals to theProvides trip signals to thegenerator or utility breakers.generator or utility breakers.

Sophisticated Sophisticated Controls and Safety Controls and Safety FeaturesFeatures