Fault powered, processor controlled circuit breaker trip system having reliable tripping operation

• US 5,038,246 A
• Filed: 08/31/1989
• Issued: 08/06/1991
• Est. Priority Date: 08/31/1989
• Status: Expired due to Term

• Current Assignee: Square D Company (Schneider Electric SE)
• Original Assignee: Square D Company (Schneider Electric SE)
• Inventors: Durivage, Leon W. III
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/403,225
• Time in Patent Office: 705 Days
• Field of Search: 361/86, 361/87, 361/88, 361/93, 361/65, 364/483
• US Class Current: 361/93.2
• CPC Class Codes: H02H 1/063 primary power being supplied by fault current
• CPC Class Codes: H02H 7/262 involving transmissions of switching or blocking orders
• CPC Class Codes: H02H 7/30 Staggered disconnection

Abstract

A fault-powered, processor-based tripping system includes a solenoid for interrupting a current path in response to a trip signal generated by a processor. The processor analyzes current provided by a current sensor, by way of an interface circuit, to determine when the trip signal should be generated. A power supply provides a reference signal to the processor to indicate the amount of power it is capable of delivering to the solenoid. Before attempting to engage the solenoid, the processor checks the level of the reference signal to determine whether or not the power supply is at that time capable of supplying the solenoid with a sufficient amount of power to effect interruption of the current path thereby avoiding a power loss by inappropriate engagement of the solenoid. If the power level is sufficient to engage the solenoid, the processor generates the trip signal to interrupt the current path.

Claims

1. A tripping system for interrupting a current path, comprising:

means for interrupting the current path in response to a trip signal;

a power supply for providing power to the means for interrupting to effect the current path interruption;

power supply sensing means, coupled to the power supply, for indicating whether or not the power supply is presently capable of supplying the means for interrupting with a sufficient amount of power to effect the current path interruption;

a current sensor for sensing current in the current path; and

generation means, responsive to the current sensor and the power supply sensing means, for engaging the means for interrupting when the power supply sensing means indicates that the power supply is presently capable of supplying the means for interrupting with a sufficient amount of power to effect the current path interruption.

2. A tripping system, according to claim 1, wherein the power supply receives current from the current path.

3. A tripping system, according to claim 2, wherein the current sensor includes a coil inductively linked to the current path, and the power supply includes a capacitor charged by current rectified from current induced in the coil.

4. A tripping system, as claimed in claim 1, wherein the generation means includes a processor programmed to determine when the current through the current path has become excessive and input data from the power supply sensing means before engaging the means for interrupting.

5. A tripping system, according to claim 4, wherein the processor further includes means responsive to the fault signal for repeatedly checking the power supply sensing means until the power supply sensing means indicates that the power supply is presently capable of supplying the means for interrupting with a sufficient amount of power to effect the current path interruption.

6. A method of using a solenoid in a fault powered tripping system to interrupt a current path, the method comprising the steps of:

a) receiving and storing energy from current flowing through the current path;

b) sensing the amount of current flowing through the current path;

c) detecting whether said energy having been received and stored is sufficient to engage the solenoid; and

d) after sensing an excessive amount of current in step b) and detecting in step c) that said energy is sufficient to engage the solenoid, energizing the solenoid to interrupt the current path.

7. A tripping system for interrupting a current path, comprising:

a sensing circuit for sensing at least one power-related parameter in the current path;

an interruption circuit for interrupting the current path in response to a trip signal;

a power control circuit, drawing power from the current path and including at least one power signal, for providing for sufficient power to the interruption circuit to effect the current path interruption;

a comparison circuit, coupled to the power supply, which indicates if said at least one power signal is greater than a predetermined value; and

means, including a microcomputer for analyzing said at least one power-related parameter, for engaging the interruption circuit in response to the analysis of said at least one power-related parameter and to the comparison circuit indicating that said at least one power signal is greater than a predetermined value.

8. A tripping system, according to claim 7, wherein the comparison circuit includes a digital buffer which generates a logic low when said at least one power signal falls below said predetermined value.

9. A tripping system for interruption at least one of a plurality of current paths in a multi-phase network, said tripping system comprising:

a plurality of sensing circuits for sensing current in each of the plurality of current paths;

a plurality of rectification circuits, respectively coupled to said rectification circuits;

a power control circuit, drawing power from the current path through said plurality of rectification circuits, said power control circuit providing sufficient power to the interruption circuit to effect the current path interruption;

at least one burden resistor coupled between the power control circuit and at least one of said plurality of rectification circuits for developing a voltage signal which corresponds to said at least one power-related parameter in at least one of the current paths;

at least two amplification circuits, arranged in parallel so that both receive said voltage signal and each having a different gain for amplifying said voltage signal so as to amplify the voltage signal in varying degrees of resolution;

an interruption circuit for interrupting the current path in response to a trip signal;

a comparison circuit, coupled to the power supply, which indicates if said at least one power signal is greater than a predetermined value; and

means, including a microcomputer for analyzing said voltage signal through said at least two amplification circuits, for engaging the interruption circuit in response to the analysis of said at least one power-related parameter and in response to the comparison circuit indicating that said at least one power signal is greater than a predetermined value.