Time ratio control circuit for contactor or the like
AssigneeSiemens-Allis, Inc.
InventorsJohn C. Culligan, Frederick A. Stich, Conrad F. Williams
Life of this patent
Estimating the term…
Abstract
A system for controlling current flow to the actuating coil of a contactor or the like. A solid state switch is provided for gating current flow to the coil, and operated by an oscillator stage. A time delay causes the oscillator to operate at a high duty cycle when power is initially applied, allowing a relatively high current to flow to the contactor coil to operate the contacts. Subsequently the control causes the oscillator to operate at a low duty cycle, wherein the solid state switch passes a significantly lower current flow to the coil to maintain the contacts in position.
Claims16
In an electromagnetic contactor including contacts for making an electric circuit, at least one of said contacts being movable, armature means coupled to said movable contact, and an electromagnetic coil for effecting movement of said armature means, means for causing current of a first, higher value to flow through said coil in order to cause said movable contact to complete a circuit and to cause current of a second, lower value to flow through said coil after said movable contact has completed the circuit, comprising:
- a first solid state electronic switch in series circuit relationship with said coil;
- oscillator means for outputting a signal;
- means coupling said oscillator means to said first switch for operating said first switch in response to the oscillator signal;
- means for causng said oscillator means to enable said first switch at a first, higher time ratio to provide said coil with a first, higher current flow for a period sufficient to allow the contacts to operate, and for causing said oscillator means to enable said first switch at a second, lower time ratio to provide said coil with a second, lower current flow after said period, said second current flow being sufficient to maintain said contacts in an operated position.
A control system for varying current flow through the actuating coil of an electric switch of the type having a pair of main contacts, one of the contacts being movable, including an armature coupled to the movable contact and responsive to energization of the actuating coil for operating the contacts, including:
- terminals coupled to a source of electric power;
- electronic switch means coupled in circuit between at least one of said terminals and said coil;
- an oscillator stage coupled to said switching means for applying a time-varying signal thereto to cause electric current to be repeatedly interrupted, the time ratio of the uninterrupted to interrupted periods determining the rate of current flow to said coil;
- timer control means coupled to said oscillator stage for causing said oscillator stage output to vary from a first time ratio for effecting a first, larger current flow through said coil to a section time ratio for effecting a second, smaller current flow.
Dependencies are inferred from the claim text.