Development of quench detection system for PF-3 coils of SST-1

Steady State Superconducting Tokamak-1 (SST-1) machine at IPR is in operation for the plasma experiments. Superconducting Magnet Systems (SCMS) of SST-1 comprising of sixteen superconducting D-shaped Toroidal Field (TF) magnets and nine superconducting Poloidal Field (PF) magnets together with a pair of resistive VF coils and Ohmic coils. The Toroidal Field (TF) magnet system is routinely operating at more than 1.5 T. PF3 coils also made superconducting successfully during last campaigns. PF3 coils are also going to be charged in up-coming campaigns. A reliable and fail proof quench detection (QD) system is essential for of the PF-3 coils operation. This QD system needs to continuously monitor all the section of PF-3TB coils, which include 4 pair of layers, bus bars and current leads. In case of any event initiating the normal resistive zone and reaching thermal run-away, the QD system needs to trigger the magnet protection circuits. In the present configuration of quench detection scheme, the voltage drop across each pair of layers of PF-3TB coils are measured and compared with its two adjacent pair of layers for the detection of normal zone and cancellation of inductive couples. During OT discharge, PF coils are coupled to induced voltage (~1 kV), which makes the development PF QD system more challenging. A proposed QD system is developed with single stage low pass filter & voltage divider before the front end of electronics, which comprises of 3.5 kV galvanic isolation, filter, difference amplifier section, comparator & timing logic. This paper describes activity continued towards the development of QD system of PF-3TB coils, precaution taken on during development and challenges and will be updated during presentation. (author)