Electricity: motive power systems – Motor-reversing – Armature or primary circuit control
Patent
1974-12-09
1976-07-20
Rubinson, Gene Z.
Electricity: motive power systems
Motor-reversing
Armature or primary circuit control
318227, 318221G, H02P 144
Patent
active
039709086
ABSTRACT:
A single-phase induction motor is provided with a simple capacitor-start control system. A precision current detector (reed relay) is used in the main winding circuit to fire a bidirectional thyristor and precisely control the starting and stopping points of energization of the start winding to cause the motor to accelerate to the desired speed. Although this small reed relay is a fast acting device that picks up on the leading side and drops out on the trailing side of each current half-cycle, chopping up of the current wave is avoided by the combination used. Thus, in view of the nearly 90 degree phase-shift between the main winding and start winding currents, the reed relay, with its dropout point being lower in current value than its pickup point on each half-cycle due to the inherent differential in its magnetic characteristics, applies a wide firing pulse to the thyristor at the most desirable time, that is, it widely overlaps the point where the start winding current passes through zero. Thus, the thyristor is force-fired at the beginning of each half-cycle for symmetrical triggering. And since the thyristor conducts for the remainder of each half-cycle, this start winding thyristor affords full-cycle conduction even though the reed switch itself is not closed throughout each half-cycle of main winding current thereby avoiding chopping up of the start winding current wave. In addition, this combination avoids hysteresis in that the current value at which the reed relay starts picking up on consecutive half-cycles and the lower current value at which it stops picking up on consecutive half-cycles are very close to one another thereby affording accurate control of the start winding.
REFERENCES:
patent: 3766457 (1973-10-01), Fink, Jr. et al.
patent: 3842327 (1974-10-01), Wexler
Hansen James E.
Schmit Eugene R.
Autio William A.
Cutler-Hammer, Inc.
Rather Hugh R.
Rubinson Gene Z.
LandOfFree
A.C. motor starting system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with A.C. motor starting system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A.C. motor starting system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-559170