GB810969A - Improvements in auxiliary supply arrangements for electric traction equipments - Google Patents

Abstract

810,969. Automatic voltage control systems; electricity supply systems. METROPOLITANVICKERS ELECTRICAL CO. Ltd. Sept. 12, 1957 [Oct. 9, 1956], No. 30760/56. Class 38 (4). The output of a dry-plate rectifier is connected in series with the armature of a buck/ boost generator, the field of which is automatically controlled to maintain the total ouput voltage constant. Regulated and unregulated auxiliary D.C. supplies are thus made available on an A.C. electric traction system. An auxiliary winding 4 on the main traction motor supply transformer 1 supplies the dry-plate rectifier 8. A booster transformer 9 enables the rectifier input voltage to be pre-set for average operating conditions and to allow for rectifier ageing. Unregulated D.C. loads such as an air-compressor motor 31 and cooling fan 33 are connected directly across the rectifier output. Loads including a battery 17, which require a stabilized supply are connected in series with the armature 12 of the buck/boost generator which is driven by a motor 12a from the A.C. supply. The generator 12 has opposed field windings 19, 20 connected across the D.C. supply, the mid-point of the windings being connected to the centre contact 21 of a moving coil voltage regulator which has field coils 27 and a moving coil 26. When the output voltage is correct, there is zero excitation as windings 19 and 20 cancel. If the voltage deviates, the voltage regulator closes contacts 21, 22 or 21, 23 thereby shunting one field winding to excite the generator in the appropriate sense, and simultaneously changing the current in the field coil 26 of the regulator to effect intermittent action. It is stated that the moving-coil regulator may be replaced by a carbon pile regulator.