Improvements in or relating to safety arrangements

摘要

1,034,717. Protective arrangements. SIEMENS-SCHUCKERTWERKE A.G. May 30, 1963 [June 1, 1962], No. 21770/63. Heading H2K. In an installation, e.g. a nuclear reactor, in which a group of three measuring devices is provided to check each variable or signal and the operation of at least two of the devices is necessary to operate a safety or shut-down system, the arrangement of the contacts of the measuring devices is such that incorrect response does not occur on the faulty operation of a measuring device in each of two groups. In the arrangement shown, each device A, B, C of a group of devices is provided with three sets of contacts a 1 , b 1 , C 1 arranged in three control lines I, II, III in the different series/parallel combinations shown. The contacts are normally closed and no control line is interrupted unless two devices of the same group operate. A relay winding S I , S II , S III is connected in each control line and the contacts of these relays are so connected that de-energization of two relays is necessary to effect the operation of the safety or shut-down system. Each parallel circuit may be provided with a test relay having opposing windings (e.g. IR I IR1 I ).