| 摘要 |
678,464. Protective cut-out systems. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Nov. 3, 1950. [March 21, 1950] No. 7074/50. Class 38 (v). A number of electric heater or similar load circuits H1<SP>1</SP>, H1<SP>11</SP> in an electric vehicle, are grouped in pairs in parallel, each pair having a contactor C1 with a common main contactor C, no-current relays R1 ... R6 being connected in the earth side of the circuit. The relay contacts r1 ... r6 are in series with a master relay MR, having a maintaining contact MR2 and a contact MR 1 in series with the contactor coils CC, CC1, the contacts r1 ...r6 being arranged so that de-energization of any relay R1 ... R6 on an earth fault in the corresponding heating circuit opens its contact to de-energize relay MR and so cause the contactors CC, CC1 to open to de-energize all the heating circuits. The contactors are reclosed by depression of a reset button RS to energize relay MR over contacts RS1 and prepare the contactor-coil circuit at MR1, this circuit being completed at contacts RS2 on release of the button, and maintained over auxiliary contactor contacts C/1. The individual contactors C1 &c. may be opened by de-energization of their coils at thermally- or pressure-actuated contacts T1 and retained open by opening isolators IS1. In a modification; Fig. 1 (not shown), the contacts of the nocurrent relays are directly in series with a single contactor coil, which when the contactor opens, closes a further auxiliary contactor contact in an indicator circuit. |
