| 摘要 |
<p>A three phase supply, control and distribution apparatus has two control units 10, 11 arranged to switch between full-power and half-power energisation of two sets of loads, particularly radiant heater, without altering the phase load balance. The half-power setting is achieved by diodes 12, 22 connected in parallel with switch contacts 14, 24 which are opened in unison when either a switch 34 or a thermostat, or a fuse 42 (supplying contactor solenoid 11, 21 and fans) open, the diodes 12, 22 being poled so that one set of loads receives positive half waves and the other set receives negative half waves. Each load set may be formed by three groups of three radiant heater star connected between the three phase output lines 13 or 23 and neutral 32. <IMAGE></p> |
