MINIMUM OFF-TIME CIRCUIT

• US 3,619,668 A
• Filed: 08/27/1970
• Issued: 11/09/1971
• Est. Priority Date: 08/27/1970
• Status: Expired due to Term

• Current Assignee: Balthasar H. Pinckaers
• Original Assignee: Balthasar H. Pinckaers
• Inventors: Pinckaers, Balthasar H.
• Primary Examiner(s): Forrer, Donald D.
• Assistant Examiner(s): Zazworsky, John
• Application Number:
  US05/067,445
• Time in Patent Office: 439 Days
• Field of Search: 307/94,141,141.4,293 317/13R,36TD
• US Class Current: 327/397
• CPC Class Codes: H02H 3/06 with automatic reconnection
• CPC Class Codes: H02H 7/0816 concerning the starting sequence, e.g. limiting the number of starts per time unit, monitoring speed during starting

Abstract

An alternating current contactor or relay which can be used for control of equipment such as refrigeration compressors is disclosed with a minimum off-time control. The minimum off-time control includes a resistor-capacitor timing circuit which charges initially from a power source through a transistor, and this is held in a charged condition while the current continues to flow through the transistor to energize a solid-state switch which energizes the contactor. In the event that a momentary interruption of power occurs, or in the event that power is removed, the capacitor starts to slowly discharge activating a second transistor circuit that shorts out the first transistor so that the output switch cannot be reenergized for some minimum period of time.

Claims

1. A time delay circuit adapted to keep a load deenergized for a minimum period of time after the load has been previously energized, including:

power supply means adapted to be connected to a source of electric power to provide direct current potential supply means;

first current control means conducting current from said direct current potential supply means to store energy in energy storage means upon initial application of power to said power supply means; and

first current control means further normally continuing to conduct to operate output means connected to control said load; and

second current control means connected to said direct current potential supply means and operable to discharge said stored energy from said energy storage means upon interruption of electric power to said power supply means;

said second current control means discharging said stored energy and disabling said first current control means thereby preventing said first current control means from conducting during said discharge to prevent said load from being reenergized by said output means for a minimum period of time.

2. A time delay circuit as described in claim 1 wherein said first current control means is a transistor connected to conduct current to said energy storage means and said output means.

3. A time delay circuit as described in claim 1 wherein said energy storage means is a capacitor.

4. A time delay circuit as described in claim 1 wherein said output means includes semiconductor switching means.

5. A time delay circuit as described in claim 1 wherein said second current control means includes two transistors with a first of said transistors connected to short out said first current control means when said first transistor iS conducting current;

and a second of said transistors is connected to discharge the stored energy from said energy storage means thereby causing said first transistor to conduct.

6. A time delay circuit as described in claim 5 wherein said first current control means is a transistor connected to conduct current to said energy storage means and said output means.

7. A time delay circuit as described in claim 6 wherein said energy storage means is a capacitor.

8. A time delay circuit as described in claim 7 wherein said output means includes semiconductor switching means.