GE Entelli-Switch 250 Initiating a Closed Transition, Re-Transfer with Closed Transition

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Testing (cont’d)

NOTICE

A periodic test of the transfer switch under load conditions is recommended to insure proper operation.

(See National Electric Code articles 700 and 701)

Closed Transition

GE Zenith Closed Transition Transfer Switches are designed to Transfer the Load between two available sources with out interrupting power to the Load (Make-Before-Break). Paralleling of the two sources occurs within a predefined window of synchronization and lasts less than 100 milliseconds. The initial Source is then disconnected.

Initiating a Closed Transition

When a Test is initiated, the controller initiates the Time Delay Source 2 Start (Engine Start Timer "P") cycle. Upon completion of the (P) time delay, an Engine start Signal is sent to Source 2. When Source 2 voltage and frequency reach the preset "Restore" values, the time delay to open Source 1 timer (W) begins its timing cycle. After the (W) time delay, the ATS closes into Source 2 only after the controller ensures the prop- er phase relationship between the two Sources. After the ATS closes into Source 2, the SE limit switch becomes activated to de-energize the CCE relay and energize the CCNO relay which opens the ATS out of Source 1. The SNO limit switch activates to de-energize the CCNO relay. The ATS has now closed into Source 2 position without interrupting the load.

Re-Transfer with Closed Transition

Deactivating the Test Switch initiates the re-transfer. When Source 1 voltage and frequency reach the preset "Restore" values, the time delay to open Source 2 timer

(T)begins its timing cycle. After the (T) time delay, the ATS closes into Source 1 only after the controller ensures the proper phase relationship between the two Sources. After the ATS closes into Source1, the SN limit switch becomes activated to de-energize the CCN relay and energize the CCEO relay which opens the ATS out of Source 2. The SEO limit switch activates to de-ener- gize the CCEO relay. The ATS has now closed back into Source 1 position without interrupting the load.

The ATS defaults to an open transition transfer when Source 1 fails. Closed transition transfer is not possible with only one source available. If the optional Transition Mode Selector (TMS) is available, one can select an Open Transition Transfer or a Closed Transition Transfer when both Sources are available..

If while in Closed Transition Mode, the ATS fails to open the source it is attempting to "transfer out of" within 100 milliseconds, an Alarm will sound and the source that the ATS just closed into will be opened leaving the ATS in its initial source while disabling all other transfer operations until the problem is corrected and the "Fail to Open Lockout Reset" has been pressed.

A signal will be provided (STE) to Shunt Trip the Generator Circuit Breaker if the Transfer Switch remains closed into both Sources for more than 325 milliseconds. The load will then be fed by the Source 1. The maximum time that the two Sources would be parallel, under these conditions, is less than 500 milliseconds. Before operating the Closed Transition Transfer Switch, the condition must be corrected and the Shunt Trip reset. Refer to procedure for servicing the Switch after Shunt Tripping occures.

The unit is Factory set to accomplish transfer within 5 electrical degrees.

Requires an Isochronous Governor with an operating frequency of 60+/- 0.2 Hz.

Requires a Shunt Trip Breaker on the Generator set with a response time not exceeding 50 milliseconds.

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Entelli-Switch 250 Operation and Maintenance Manual (71R-2000)

GE Zenith Controls ■

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Contents GE Zenith Controls Table of Contents Authorized ServiceIntroduction Equipment Inspection and Storage Safety / InstallationFinal Equipment Inspection Engine Start Control Connections Installation cont’dInitial Energization Initial Energization cont’d R E T E S TInstallation cont’d Entelli-Switch 250 Controller Entelli-Switch 250 ControllerEntelli-Switch 250 Controller cont’d LCD & KeypadUser Setting for Voltage & Frequency Accessory Group Packages Stds Exes Cons Sens Spes PsgsA62 Accessory DefinitionsCalibrate Accessory Definitions cont’d S13P Approximate out of phase degreesS12P S14How to Set the System Clock Press More and scroll to SET System Clock using the More keyPress Bypass Exer CDT One Event Timer ExerciserPress Exer Cancl Press Start Timer Test Press Cancl BpassCDP Clock Exerciser Load / No-Load Clock ExerciserEntelli-Switch 250 User Setup CFG Menu Turn options on or OFF via keypad through the CFG menuEntelli-Switch 250 User Setup SET Menu Change adjustable values through the SET menuEntelli-Switch 250 User Setup System Info View System DataTest Options TestingIntroduction Auto PositionDelayed Transition Testing cont’dATS Testing Standard TransitionInitiating a Closed Transition Closed TransitionRe-Transfer with Closed Transition Auto Location Emergency Service Procedure for Extended Parallel TimeTest Location Sequence of Operation ATS TypeSequence of Operation cont’d Amp Molded Power Section Transformer Usage see Figure Relay/Transformer R/T BoxDelayed / Closed Transition Relay/Transformer R/T Box cont’dStandard Transition R/T Box Schematic Delayed / Closed Transition R/T Box SchematicTroubleshooting and Diagnostics General TroubleshootingTesting Maintenance and TestingInspection and Cleaning ServicingPage GE Zenith Controls
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