ISAC Safety System PLC and Display Changes

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 The ISAC Safety System (ISS) PLC code and display have been changed to accommodate two new signals that will eventually originate from ISAC Controls. This note outlines how the ISS processes the signals. Details on how the signals are generated will have to be provided by ISAC Controls and/or device owners.

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The first new signal, (green) NIMS OK, summarizes the status of devices SEBT:NIM10 and SEBT:NIM18, two ISAC Vault Non-Intercepting Monitors who’s purpose is to ensure that beams with parameter levels above pre-determined set points are contained in the Vault and not delivered to the ISAC II Experimental Area. If any set point is exceeded during beam delivery to the Experimental Area the ISS will display (red) NIMS NOT OK, generate a Vault ISS TRIP, and drive in source Faraday cups as well as SEBT:BB20, the Vault beam blocker downstream of the SC-linac. After the ISS receives indication that SEBT:BB20 has indeed reached its in limit, its interlock logic will allow the trip to be reset and the source Faraday cups to be re-enabled and driven out, permitting beam tuning to take place in the Vault. Parameter levels above set points must be tuned to be below set points before the NIMS NOT OK signal can be reset and SEBT:BB20 can be re-enabled and driven out again, resuming safe beam delivery to the Experimental Area.

ISAC Controls must latch the NIMS NOT OK signal in their own system. They also provide the reset for any OK to NOT OK transition and will issue appropriate instructions.

The signal is wired OK in the ISS at this moment but the wiring to ISAC Controls is complete and the devices interface has been installed. I expect commissioning to begin fairly soon.

The second new signal, (green) RFQ FC OK will work in a similar fashion however the device itself is only in the very early design stage. The signal is also wired OK in the ISS and will remain that way for some time.

The requirement for these two new signals and how they ensure safe beam delivery to the ISAC Experimental Area is documented in the original TRIUMF-ISAC II Safety Report sections 8.1.3.1 and 8.1.3.2, available on Docushare.

Some other elements of the ISS display have been re-organized for clarity.

See ISACDocuments/Plone documents/ The ISAC2 SC Linac Over current Monitoring System for more information about this topic.