| 摘要 |
<p>466,893. Controllers. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 9, 1935, No. 34091. Convention date, Dec. 7, 1934. [Class 38 (iii)] Combination of resistances.-Control equipment for a direct-current drive comprises a main resistance provided with tappings 1-4 dividing it into sections, and a variable resistance connected in parallel with each of the sections in succession, one end of the main resistance being connected to one end of the variable resistance and each intermediate tapping being provided with a pair of independent switches 2a, 2b, 3a, 3b, 4a, 4b, for selectively connecting it to either of the effective ends of the variable resistance. The variable resistance is regulated by a commutator-type of switch having end segments A, E, while the switches 2a, 2b, .... are in the form of a drum switch. When the controller is operated the switch 2a first closes to connect the variable resistance in parallel with the first section 1-2 of the main resistance, the variable resistance being then gradually reduced. Switches 2b, and 3a are then closed and the switch 2a opened, the commutator-type switch moving to its initial position. Similar switching operations are effected for each section of main resistance by further operation of the controller. When the main resistance section 3-4 has been cut out, the switches 4a, 4b are closed and share the load in disconnecting. The variable resistance is preferably adjusted to absorb only a fraction of the main current, and its divisions may decrease continuously in ohmic value from the full resistance position to the low resistance position. The main resistance may be used on a vehicle for heating.</p> |
