GB566911A - Electrical control device for intermittently operating apparatus - Google Patents

Abstract

566,911. Control systems for consumption apparatus. LINDARS, H. July 29, 1943, No. 12345. [Class 38 (iv)] [Also in Group XXXVII] Switching control.-The switching on and off of an electrical apparatus, which is required to be operative during a succession of periods separated by inoperative periods, is effected at the contacts 8 of a relay R1, the energization of which is controlled by rotary switches A1-A4 and B1-B3. Switches A1-A4 are driven by a synchronous or other motor A and control the length of the periods during which the apparatus is operative, whilst switches B1-B3, which are driven by a reversible motor B control the length of the inoperative periods. The switches A1, A2 and B1 consist of earthed conducting discs fitted with insulating segments A1<SP>1</SP>, A2<SP>1</SP>, B1<SP>1</SP>, whilst the remaining switches are in the form of insulating discs having conducting segments A3<SP>1</SP>, A4<SP>1</SP>, B2<SP>1</SP>, B3<SP>1</SP>. The cycle of operations is as follows : a starting circuit for motor A is completed under the control of a contact operated by motor B and rotation of motor A causes the closing of its own running circuit from line 14 to earth as the segment A1<SP>1</SP> moves off the fixed contact 1 of switch A1 ; relay R1 is then energized from line 16 as segment A4<SP>1</SP> passes under the fixed contact of switch A4, thereby closing the load contacts 8 and establishing a self-maintaining circuit over its contacts 9 and an adjustable " operative period " timing contact 2 of switch A2. The relay remains energized until the selfmaintaining circuit is broken by the passage of segment A2<SP>1</SP> under contact 2. Motor A stops when segment A1<SP>1</SP> again reaches contact 1, but just prior to this a starting circuit for motor B is closed over contacts A3<SP>1</SP>, 3 of switch A3, this motor being supplied from a line 21 over reversing contacts 12 of a relay R2. Motor B is independent of contacts 3, A3<SP>1</SP> as soon as segment B1<SP>1</SP> moves off fixed contact 5 and continues to run in a clockwise direction until segment B3<SP>1</SP> reaches an adjustable " non-operative period " timing contact 7 of switch B3, which closes the circuit of R2, thereby throwing over the contacts 12 and causing the motor to run in the reverse direction until stopped by the segment B1<SP>1</SP> again reaching contact 5. During reversal, a self-holding circuit for the relay is provided over its contacts 10. Just prior to stopping, segment B2<SP>1</SP> and its co-operating fixed contact 6 close the starting circuit for motor A over the relay contacts 11 and conductor 25. The holding circuit of the relay is broken when segment B1<SP>1</SP> returns to its initial position. In modified arrangements, the two sets of switches are driven by a single motor clutched to each set alternately and reversal of motor B is effected by a switch mechanically operated from its spindle; whilst the switches may be in the form of make - and - break contacts operated by discs provided with projections or indentations.