. Electric railway journal . me the load fell momentarily below its form of time element was therefore found to beessential. The use of oil or air dash pots, or of air bellows,was considered impracticable due to their inherent -unreli-ability which is especially great when long-time elementsare required. The first form of time relay tried was asolenoid with a heavy moving core, to which a gear trainand fan were connected by an over-running clutch. Thisrelay would pick up instantly without driving the geartrain but would have to drive the gear. This relay operated many thousand tim
. Electric railway journal . me the load fell momentarily below its form of time element was therefore found to beessential. The use of oil or air dash pots, or of air bellows,was considered impracticable due to their inherent -unreli-ability which is especially great when long-time elementsare required. The first form of time relay tried was asolenoid with a heavy moving core, to which a gear trainand fan were connected by an over-running clutch. Thisrelay would pick up instantly without driving the geartrain but would have to drive the gear. This relay operated many thousand times but it was ofnecessity built with rather delicate parts and its maximumtime setting was about five minutes. It frequently stuck,due to the excessive mechanical friction as compared tothe driving force, the weight of the plunger being con-siderable. To secure a greater length of travel, this same principlewas adopted, the operation being by means of a small motorwhich wound up a weight on a drum, the weight in turn Trolley. H«il^ . T (J Operating Coils of Relays etc. ~ Contact Closed for De-encrgiied Condition of Relay Open for De-energizedCondition of Relay etc. , , Main Contacts of the FieldContactors l?gl Relay Resistance SIMPLE STRAIGHT-LINE DIAGRAM, ELIMINATING SNEAK CIRCUITS 1. Under-voltage relay. 2. Low-voltage ^elay relay. 3. shunt relay. 4. shunt relay. 5. Field contactor normal field. 6. starting contactor. 7a. Armature of polarized motorrelay. 7b. Field of polarized motor relay. 8. shunt relay. 9. relay for field 10. Field contactor reversed field. 11. running contactor. 12. line switch. 13. series underload relay. 14. 15, 16. line resistanceshunting switches. 12a, 14a, 15a. acceleratingrelays. 17. Two-pole knife switch. 18. Reverse-phase and relay. 19. shunt relay. 20. Main oil switch in powerline. 20a. Low-voltage release on 20. 21. dash-pot re
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyorkmcgrawhillp
