GB1195581A - Electrical Device for Indicating Instantaneous Value of A.C. - Google Patents

Abstract

1,195,581. Saturable reactor arrangements. MINISTER OF TECHNOLOGY. 18 July, 1968 [19 April, 1967], No. 17895/67. Heading H3B. [Also in Division H2] A saturable reactor arrangement comprises a main winding 4, Fig. 1, carrying alternating current proportional to the current through a load 13, and a secondary winding 6a, 6b inductively decoupled from the main winding and carrying current from an alternating source 9 of higher frequency than that through the main winding, the reactor being dimensioned such that the secondary winding current reduces abruptly each time the main winding current desaturates the core by falling below a predetermined instantaneous value in each half cycle. The reduction of secondary winding current is detected by an indicator, recorder or actuation coil 11 which remains operated until the main winding current next exceeds the predetermined instantaneous value. The arrangement may be used in a cycloconverter system, Fig. 4, in which a polyphase supply is converted to a lower frequency and applied to a load 13 by cyclically gated thyristors or gridcontrolled mercury arc rectifiers in rectifier groups 14, 15. Each path from a rectifier group to the load includes a saturable reactor arrangement 18 as shown in Fig. 1 which overrides a control circuit 16, 17 so as to prevent any rectifier in a group from being switched on until current from the other rectifier group falls below a predetermined instantaneous value. In a modification, Fig. 2 (not shown), the main winding consists of two separate coils. Alternatively a single three-limbed core may be used, Fig. 3 (not shown).