GE Entelli-Switch 250 Manuel d'utilisateur télécharger pdf (Page 25)

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GE Zenith Controls 25

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

Sequence of Operation

(cont’d)

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

proper 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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GE Entelli-Switch 250 Manuel d'utilisateur Page 25

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