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
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
Re-Transfer with Closed Transition
Deactivating the Test Switch initiates the
(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
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.
■ GE Zenith Controls | 25 ■ |
