Abstract:
An electronic circuit interruption device having a plurality of protection, indication and control options includes a dedicated printed circuit board having electrical connection with operating circuits controlling each of the several options. Electrical connections between the operating circuits and the circuit interruption controller is made through corresponding dedicated resistors. Option selection is obtained by removal of resistors connecting with non-selected circuits on the printed circuit board.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to circuit breakers, and, more particularly, to a method and arrangement for customizing electronic circuit interrupters. 
     Multifunctional electronic circuit interrupters, such as described in U.S. Pat. No. 4,672,501 entitled Circuit Breaker and Protective Relay Unit, are capable of providing a plurality of optional protection functions, such undervoltage, overvoltage, phase loss, phase imbalance as well as remote control and indication functions, such as shunt trip, bell alarms and the like. Most commercial applications using such circuit interrupters do not require all the accessory functions and options, such that the circuit interrupters are usually customized for each specific function. 
     U.S. Pat. No. 5,500,781 entitled Digital Circuit Interrupter with Multiple Accessory Function, describes the use of selection switches that allow factory as well as field selection of the preferred protection and accessory options. Normally-open switches connect through OR logic gates with options circuits, allowing the selected functions to become operational through selected switch closure. This manual selection arrangement is sufficient when a limited number of circuit interrupters are employed. 
     The automatic insertion of electronic components within printed circuit boards in a high speed manufacturing process is described within U.S. Pat. No. 3,676,746 entitled Compatible Modular Circuit Board Connector, and U.S. Pat. No. 4,670,977 entitled Inserter Device for Electronic Components. 
     SUMMARY OF THE INVENTION 
     In an exemplary embodiment of the invention, an electronic circuit interruption device having a plurality of protection, indication and control options includes a dedicated printed circuit board having electrical connection with operating circuits controlling each of the several options. Electrical connections between the operating circuits and the circuit interruption controller are made through corresponding dedicated resistors. The resistors are arranged at a predetermined edge of the printed circuit board for access by means of an arbor tool sized to overlay the resistors for removal thereof without interfering with the circuit board substrate. Option selection is obtained by removal of resistors connecting with non-selected circuits on the printed circuit board. Logic is provided to the arbor by a computer-controlled stepper motor. When large numbers of circuit interrupters require specific protection, indication and control options, selection using the method of the present invention can be made early in the circuit interrupter manufacturing process at substantial cost savings over the prior art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagrammatic representation of an electronic trip unit employing the trip unit calibration system according to the invention; 
     FIG. 2 is a block diagram of a part of the microprocessor circuit within the electronic trip unit of FIG. 1; 
     FIG. 3 is a side view of the apparatus used with the trip unit calibration system according to the invention; and 
     FIG. 4 is an enlarged side view of the cutting tool used with the trip unit calibration apparatus of FIG.  3 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG.  1  and as described in the aforementioned U.S. Pat. No. 4,672,501 (which is incorporated by reference), a circuit breaker trip unit  10  is shown. Trip unit  10  has external connections to current transformers  11 - 14  and potential transformers  15 - 17 . The electrical input is transmitted through multiplexers  18 - 20  and sample and hold amplifiers  21 ,  22  to an A/D (analog-to-digital) converter  24  by a conductor  23 . Circuit protection and control is achieved by utilization of a data bus  25  which is interconnected with an output control  26 , transceiver  27 , and RAM (random access memory)  28 . The ROM (read only memory)  29 , microprocessor  30  and NVM (non-volatile memory)  31  operate in the manner described therein to insure complete overall circuit protection. The information as to the status of the circuit breaker contacts (not shown) that are controlled by the output control  26  is displayed at a display  32 . In accordance with the invention, the microprocessor  30  is provided with a resistor circuit  33  that allow selection of the circuit breaker ampere rating and other optional functions. Other functions available to the microprocessor for selection during the assembly of the circuit breaker trip unit  10  include undervoltage and overvoltage determination, shunt trip, bell alarm accessories and the like. 
     The microprocessor  30  is shown in FIG. 2 mounted to a printed circuit board  34 , in the form of a glass-filled fiber board  35  by pins  38  that extend through apertures, such as depicted at  47  which are then solder-filled to provide electrical connections as depicted at  37 , as is known in the art. As is common with most printed circuit connections, fuses  48  and conductive rails  36  are integrally-formed on the surface of the printed circuit board to facilitate connection with and to protect the printed circuit board components. In an exemplary embodiment of the invention, a resistor circuit  33  with resistors  39 - 46  aligned in array format, has each resistor extending upwards from the printed circuit board. Rating and option selection is accomplished by removing selected resistors  39 - 46  that connect with the microprocessor by means of rail electrical connections with pins  38  that extend from the microprocessor on the opposite side of the printed circuit board (FIG.  4 ). As described hereinbefore, the resistor circuit  33  connects with the microprocessor  30  by means of the databus  25  (FIG. 1) such that the presence of selected ones of the resistors  39 - 46  is determined by the microprocessor allowing the circuits associated with the selected resistors to become activated. 
     Customization of electronic trip unit  10  is achieved by removing selected ones of the resistors  39 - 46  (FIG. 3) using a transfer table  49  driven by a gear  50  and a drive train  51  under command of a controller  52 . One such arrangement is a type GRMTR servo-motor obtained from Pitman Co. The printed circuit board  34  is arranged edgewise on the top of the transfer table with the resistor array parallel with the travel direction of the transfer table, as indicated. A stepper motor  55  is programmed for removing specific one(s) of the resistors  39 - 46 , depending upon the selected rating or functions. The arbor  53  operatively connects with the stepper motor and terminates at the opposite end in a formed tool, as indicated at  54 . 
     The removal of selected one(s) of the resistors is best understood by now referring to FIG. 4 wherein the printed circuit board  34  (FIG. 2) is shown positioned on the transfer table  49 , shown in phantom with the microprocessor  30  attached to the printed circuit board by connection of the pins  38 , extending from the bottom, within the printed circuit board apertures  47 . An important feature of the invention is the arrangement of the tool  54  at the end of the arbor  53  relative to the selected resistor  46 , for example from resistor circuit  33  (FIG.  2 ). The selected resistor  46  is of cylinder configuration and extends a distance “h” upwards from the printed circuit board  34 . A slot  56 , within the tool  54 , is configured a width “w” for clearance of the length “l” of the selected resistor  46  and the depth “d” of the slot  56  is configured for clearance of the distance “h” whereby the selected resistor  46  is broken (cut) away by the twisting action of tool  54  without contact with or damage to the top surface of the printed circuit board  34 . 
     An arrangement has been shown herein for automatic selection of a circuit breaker printed circuit board ampere rating along with circuit breaker accessory options. Resistors are assigned to the particular ratings and options for reading by the microprocessor within the trip unit circuit. Removal of particular one(s) of the resistors at the time of manufacture results in a plurality of trip units having the selected ratings and functions within an automated process at a minimum of time and expense. 
     While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention may not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.