In-Line Control in T2K Proton Beam Line Magnet Safety System

Magnet Safety Systems (MSS) frequently use quench detection based on voltage measurement, in order to protect superconducting magnets. Disconnecting quench detection cables and using a voltage generator to simulate quench voltages is a good way to check the system. This paper describes another method, with a hardware and software in-line control system, used to periodically check the MSS of the 28 superconducting magnets of the T2K proton beam line, at J-PARC. With in-line control, an isolated simulation voltage is added to each real input voltage of the detectors, without disconnecting quench detection cables. In-line control can also check if quench detection cables are connected or not, and if a detection wire is broken. In-line control is realized with additional electronic hardware and software on the MSS electronic boards and with a connection to a PC with a specific software and Graphic User Interface running under Windows. Nevertheless, quench detection and safety actions are always based on hardware only. Extreme care is taken so that in-line control cannot prevent the MSS to protect the magnet system, even if software stops running. Other remote functions are also available with this system, like monitoring of analog and logical signals and setting of detection and electronic parameters, if needed.