GB743076A - Recording means for underwater ultrasonic detecting systems - Google Patents

Abstract

743,076. Control of A.C. motors. MINNEAPOLIS-HONEYWELL REGULATOR CO. March 10, 1953 [March 10, 1952], No. 6563/53. Class_38(3) [Also in Group XIX, XXXVIII and XL (c)] An ultrasonic direction finder (see Group XXXVIII) has a directional radiating element which may be rotated continuously in either direction or oscillated automatically within a selected sector, the radiating element being driven by a splitphase motor 128. As shown an earthed A.C. supply is applied to a low-impedance winding 134 of the motor via a phase-shift capacitor 138 and to a control winding 130 via master switch 146, a speedcontrol variable resistor 148 and contacts 142, 144 of a reversing relay 140 controlled by switch 150 in the live side of its A.C. supply, the relay winding being normally earthed through contact 154 of a relay 156 which is interconnected with a relay 170, each winding of the two relays being connected to the live side of the A.C. supply through sector scan switch 158 and to ground through the contacts 154, 163 of the other relay. The relays 156, 170 are such that when switch 158 is closed one relay, e.g. 170, operates first thereby preventing energization of the other relay 156. The limits of the sector scan are determined by adjustable contacts 164, 162 connected to the earthy sides of relays 140 and 156 respectively, the contacts being engaged by an earthed switch arm 160 rotated by the motor. To effect an oscillating scan. reversing switch 150 is first closed causing the motor and switch arm 160 to rotate in a counterclockwise direction. Sector scan switch 158 is then closed thereby energizing relay 170 to open contact 168 but the reversing relay 140 is not affected until switch arm 160 engages contact 162 when relay 156 is energized for an appreciable period thereby de-energizing relays 140 and 170 causing reversal of the motor and maintaining energization of relay 156 via the closed contacts of relay 170; when arm 160 engages contact 164. relays 140, 156 and 170 change over and hence the arm 160' oscillates between contacts 162 and 164.