RELAY CONTROL RESPONSIVE TO OVERVOLTAGE AND UNDERVOLTAGE

• US 3,657,603 A
• Filed: 07/24/1970
• Issued: 04/18/1972
• Est. Priority Date: 07/24/1970
• Status: Expired due to Term

• Current Assignee: William M. Adams
• Original Assignee: William M. Adams
• Inventors: Adams, William M.
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Fendelman, Harvey
• Application Number:
  US05/057,965
• Time in Patent Office: 634 Days
• Field of Search: 317/22,31,33,16,36TD,49,50,141S,142R,142TD,51
• US Class Current: 361/56
• CPC Class Codes: H02H 3/207 also responsive to under-voltage window comparators for indication G01R19/165
• CPC Class Codes: H02H 3/247 having timing means

Abstract

A line voltage guard circuit having a network including neon lamps, resistor-capacitor timing branches, diodes and transistors, the network being connected to a switching relay to control the availability of the supply line voltage to apparatus utilizing same and to disconnect the supply line from the apparatus when the line voltage is either below a bottom limit for a definite length of time or above a top limit. The circuit automatically reconnects the line to the apparatus a predetermined time after the supply voltage returns to a value between the top and bottom limits.

Claims

1. In a control system, a control relay having switch contacts for connecting a load device to a source of voltage, and means for actuating said relay comprising circuit means including a series transistor connecting said relay to said source, said transistor having a control electrode, a bias voltage branch circuit connected across said source, said branch circuit including a glow discharge lamp and an impedance in series, means connecting the junction between said lamp and impedance to said control electrode, said impedance being sufficient to provide forward bias on said control electrode when the source voltage is great enough to fire said glow discharge lamp, whereby to energize said control relay, means to substantially shunt the series-connected glow lamp and impedance, whereby to deenergize said relay, responsive to a predetermined limit value of source voltage, wherein said shunting means comprises a second transistor connected across said series-connected glow lamp and impedance, said second transistor having a control electrode, and means to provide forward bias voltage to said last-named control electrode responsive to said limit value of source voltage, wherein said means to apply said last-named forward bias voltage comprises a voltage divider impedance branch connected across said source, and circuit means including a second glow discharge lamp connecting a selected point on said voltage divided impedance branch to said last-named control electrode, said selected point corresponding to a predetermined high limit of source voltage, and means to periodically lower the voltage applied to said second glow discharge lamp sufficiently to periodically deionize said second glow lamp.

2. The control system of claim 1, and wherein said means to periodically lower the voltage applied to said second lamp comprises a relaxation oscillator connected across a portion of said voltage divider impedance branch.

3. The control system of claim 2 and the further means to apply forward bias voltage to said last-named control electrode responsive to a predetermined low limit of source voltage.

4. The control system of claim 3, and wherein said further means comprises a second voltage divider impedance branch connected across said source, circuit means including a third glow discharge lamp connecting said last-named control electrode to a selected point on said second voltage divider impedance branch, and a third transistor connected across said third glow discharge lamp, said third transistor having a control electrode connected to said last-named selected point, said last-named selected point providing a conduction level of the third transistor such that the third glow discharge lamp will ionize only at a source voltage below said predetermined low limit.

5. The control system of claim 4, and means to delay ionization of said third glow discharge lamp.

6. The control system of claim 5, and wherein said delay means comprises a series-resistance capacitance branch connected across said second voltage divider impedance branch, with the third glow discharge lamp connected between the resistance-capacitance junction of said resistance-capacitance branch and one terminal of said second voltage divider impedance branch.

7. The control system of claim 1, and delay means comprising a capacitor connected across said series-connected glow lamp and impedance to provide a time delay in applying forward bias voltage to said control eleCtrode.