GB1407674A - Pneumatic timer attachment for type m relay - Google Patents

Abstract

1407674 Electromagnetic relays; retractive switches SQUARE D CO 4 Aug 1972 [6 Aug 1971] 36977/71 Heading H1N [Also in Division F2] An adjustable delay between the manual (Fig. 11) or electromagnetic (Fig. 8) actuation and the operation of contacts 135, 136, 138 of a snap-action switch is provided by the restricted flow of air into the diaphragm bounded chamber 96, Fig. 3, of a pneumatic timer (for detailed operation see Division F2). The movable contacts 138 of the snap-action switch are carried by a contact bridge 140 slidably mounted on a contact carrier 132 by two toggle springs 148, 150 inserted in indentations 144 forming a fulcrum 142. When, on movement of the contact carrier 132, the fulcrum 142 is shifted from one side of the bridge 140 to the other, the movable contacts 138 shift from one pair of fixed contacts to the other. Upward movement of the contact carrier 132 is effected by a push-button 285, Fig. 11 or by the de-energization of an electromagnetic relay 250, Fig. 8, When the relay is de-energized, the armature 258 and relay contact carrier 48 (also in Fig. 1, not shown) are urged upwardly by springs (not shown). This causes a rocker 14 to rotate clockwise and engage the offset foot 154 of the contact carrier 132, to move it upwards. Toggle springs 148, 150 are moved over centre, and the movable contacts 138 move from the upper to the lower pair of fixed contacts. At the same time the upward movement of the contact carrier moves a rod 109 upwardly against a spring 122, and a valve opens to exhaust the timing chamber 96. The timer is now set for the timing stroke. This is initiated by releasing the push-putton, Fig. 11 or energizing the relay 250. The armature 258 is attracted to the core 256 and the armature 258 and relay contact carrier 48 are moved rapidly downwardly away from the contact carrier 132, and the rocker 14 rotates anti-clockwise away from the carrier. The carrier 132 is urged downwardly by the spring 122 against the bias of the toggle springs 148, 150. This downward movement, which will open the lower contacts and close the upper contacts, is delayed by the rate at which air can enter the chamber 96 from the atmosphere. To provide instead a time delay between de-energization of the relay 250 and operation of the snap-action switch, the timer/switch attachment (Fig. 3) is removed from the relay 250 and rotated through 180 degrees so that the offset foot 154 of the contact carrier 132 projects in the opposite direction (Fig. 10, not shown). A screwdriver slot in the rocker 14 allows manual actuation to test the timer and snap-action switch without energizing or de-energizing the relay 250.