UNDERVOLTAGE DETECTION AND ENERGY STORAGE TRIP CURRENT

• US 3,590,325 A
• Filed: 03/16/1970
• Issued: 06/29/1971
• Est. Priority Date: 03/16/1970
• Status: Expired due to Term

• Current Assignee: N/A
• Original Assignee: N/A
• Time in Patent Office: 470 Days
• US Class Current: 361/92
• CPC Class Codes: H02H 1/06 Arrangements for supplying operative power power supply arrangements in general G05F, H02M
• CPC Class Codes: H02H 11/006 in case of too high or too low voltage

Abstract

A circuit for sensing an undervoltage condition of a circuit breaker control power supply voltage. This circuit upon sensing the low voltage prevents the circuit breaker from being closed if it is open and opens the circuit breaker if it is closed and at the same time may actuate an alarm.

Claims

1. A control system for responding to a predetermined undervoltage condition in the control power supply for a circuit breaker having main separable contacts and including a trip coil and a closing means which may be selectively energized from said power supply, comprising voltage sensing means which connected to said power supply for changing from a first operating condition to a second operating condition when the voltage of said power supply decreases below a predetermined value, energy storage means connected to said power supply and normally having energy from said power supply stored at a predetermined level, said voltage sensing means having first means connected in circuit relation with said energy storage means and said trip coil for energizing said trip coil from said energy storage means when said voltage sensing means changes to said second operating condition to open said main contacts if said circuit breaker is closed, said voltage sensing means including second means connected in circuit relation with said closing means to prevent the energizing of said closing means from said power supply when said voltage sensing means changes to said second operating condition.

2. A system for the detection of and protection against the adverse effects of a low voltage in the power supply of a control circuit for a circuit breaker having a closing spring, a mechanical linkage, a trip coil, a closing coil and main contacts, comprising an undervoltage sensing device connected to said power supply, an energy storing means connected to said power supply, said energy storage means being capable of storing sufficient charge to flow at a rate capable of energizing said trip coil, said energy storage means deriving its charge initially from the power supply of the control circuit, said energy storage means being isolated from said power supply by a first diode connected between said energy storage means said power supply to permit only charging current to flow to said energy storage means from said power supply, a set of two contacts associated with the undervoltage sensing device, one of said contacts being normally open, the other of said contact being normally closed, said normally closed contact being connected in circuit relationship with the power supply and said closing coil, said trip coil being disposed upon energization to release said closing spring which actuates said mechanical linkage which closes the main contacts of said circuit breaker, said normally open contact being connected in circuit relationship with said energy storage means and said trip coil, said normally open contact having two terminals which are electrically isolated from said power supply at one terminal of said contact by said first diode and at the other terminal by a second diode connected between said contact and said power supply, said undervoltage sensing device being responsive to the presence of less than a predetermined voltage at the power supply of said control circuit to close the normally open contact connected between said energy storage means and the said trip coil thus energizing said trip coil to trip said circuit breaker and open said main contacts and to open the normally closed contact to prevent energizing said closing coil and the subsequent reclosing of said main contacts.

3. A system as described in claim 2, wherein said undervoltage sensing device has a normally open third contact, and an alarm and aSsociated power supply is connected in circuit relationship with said third contact, said third contact being closed to activate the alarm upon the sensing of low voltage by the undervoltage sensing device.

4. A system as described in claim 3, wherein said energy storage means comprises an energy storage capacitor.

5. A system as described in claim 3, wherein said energy storage means comprises an energy storage battery.

6. A system as described in claim 5, wherein said energy storage battery comprises a rechargeable energy storage battery.