BACKGROUND OF THE INVENTION

U.S. Patent 4,672,501 entitled "Circuit Breaker and Protective Relay Unit" describes the use of a digital circuit interrupter employing a microprocessor in combination with ROM and RAM memory elements to provide both relaying as well as protection function to an electrical distribution system. The associated electronic trip unit is contained on printed circuit cards that are positioned within a recess in the digital circuit interrupter cover.

U.S. Patent 4,870,531 entitled "Circuit Breaker with Removable Display and Keypad" describes a digital display and keypad used to select circuit breaker trip settings and allows the settings to be viewed.

U.S. Patent Application serial no. (41PR7170) entitled "Digital Circuit Interrupter with Multiple Accessory Function" describes an integrated circuit breaker having several accessory functions along with automatic overcurrent protection, which allows selection between the various accessory functions in different combinations. Separate switches arranged on the circuit interrupter trip unit allow factory as well as field selection of the accessory function combinations. The selected accessory units are inserted in the circuit interrupter cover adjacent to the trip unit. U.S. Patent Application serial no. (41PR7175) entitled "Bell Alarm and Lock-out Accessory for a

Digital Circuit Interrupter" describes one such accessory unit used within the aforementioned "Circuit Interrupter with Multiple Accessory Function. One purpose of the instant invention is to provide an arrangement whereby several accessory units can be electrically-connected with the circuit breaker trip unit. An additional purpose is to interlock the circuit breaker trip unit with the circuit breaker operating mechanism. A further purpose of the invention is to insure that the accessory units are properly interconnected within the trip unit circuit.

SUMMARY OF THE INVENTION

The circuit breaker electronic trip unit controlling a high ampere-rated circuit breaker is contained within a recess in the circuit breaker cover and is interlocked with the circuit breaker operating mechanism by means of a support platform to articulate the operating mechanism upon removal. The circuit breaker accessory units are mounted on the same support platform. Rejection pins on the accessories insure that the correct accessories are connected within the corresponding accessory compartments.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a top perspective view of a high ampere-rated circuit breaker containing the

electronic trip unit and accessory modules compartment according to the invention;

Figure 2 is a top perspective view of the circuit breaker of Figure 1 with the trip unit and accessory modules support assembly in isometric projection;

Figures 3A, 3B are top plan views of the circuit breaker tip unit interlock arrangement on the trip unit and accessory modules support assembly of Figure 1;

Figure 4 is a side view of the trip unit depicted in Figure l; and

Figure 5 is an enlarged front view of the bell alarm and lock-out accessory of Figure 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The high ampere-rated circuit breaker 10 shown in Figure 1 is capable of transferring several thousand amperes quiescent circuit current at several hundred volts potential without overheating. The circuit breaker consists of an electrically insulated base 11 to which an intermediate cover 13 of similar insulative material is attached prior to attaching the top c ov e r 15 , a l s o c o n s i s t i ng o f a n electrically-insulat ive material. Electrical connection with the interior current-carrying components is made by load terminal straps 12 extending from one side of the base and line terminal straps (not shown) extending from the

opposite side thereof. The interior components are controlled by an electronic trip unit 17 contained within a recess 24 in the top surface of the top cover 15. The trip unit is similar to that described within the aforementioned U.S. Patent 4,581,181 and interacts with the accessories 22 contained within said recess, such as the bell alarm and lock-out accessory 22A described within U.S. Patent Application (41PR7179) entitled "Bell Alarm and Lock-out Accessory for High Current Circuit Breakers" which includes a combined indicator and reset button 22B extending from the top thereof. The trip unit includes a display 19 for indicating the stored trip parameters along with the nature and time of the trip occurrence. The key pad 18 allows the circuit breaker memory elements to be accessed for the trip parameters. The rating plug 21 allows the circuit breaker ampere rating to be set in the manner described within U.S. Patent 4,728,914. A battery compartment cover 20 allows access to the auxiliary power batteries as described within the aforementioned U.S. Patent Application Serial No. 08/200,048 filed February 22, 1994 entitled "Digital Circuit Interrupter with Battery Back-up Facility". An operating handle 14 provides means for manually resetting the circuit breaker operating mechanism after a circuit interruption as well as for moving the circuit breaker contacts between their OPEN and CLOSED positions. Buttons 16A, 16B allow the operator to open and close the circuit breaker operating mechanism.

The circuit breaker 10 is shown in Figure 2 with the trip unit and accessory compartment removed from the recess 24. Electrical connection

between the circuit breaker electrical components and the trip unit is made by means of the terminal receptacle 26 and the wire hardness 27. Electrical connection between the electrical components and the accessories are made by means of the individual receptacles 28 inserted into holes 38 in the support platform 52. The accessories-trip unit support 29 includes a top support platform 30 which receives the trip unit 17 (Figure 1) . The terminal receptacle 26 is inserted within the elongated slot 37 formed in the top surface of the platform and trip unit retainer aperture 40 is formed to receive the retainer stud 45 extending from the rear of the trip unit as shown in Figure 4. Referring back to Figure 2, a trip unit retainer slide 39 is arranged on the bottom surface of the platform and is manually accessible by means of the downwardly depending tab 39A. The accessory housing 31 includes compartments that are open at the top and bottom. When the accessory housing is positioned on the bottom support platform 52, the individual compartments overlie corresponding connector receptacles 28 as well as the rejection apertures 47. The accessory housing is attached to the bottom support platform by means of the thru-holes 35 within the front and rear rims 33, 34 and the thru-holes 36 within the bottom of the accessory housing and screws or other suitable fasteners.

The interlock between the trip unit and the circuit breaker operating mechanism is best seen by referring jointly to Figure 3A, Figure 3B and Figure 4. In Figure 3A, the retainer slide 39 is in the lock-out position. The slide is carried by means of studs 43 and elongated slots 42 and is biased to the lock-out position by means of the

extension spring 53. The key-hole shaped slot 41 formed in the central part of the slide defines a first diameter A. and a larger diameter £. In the lock-out position, a part of the slide as shown at 41A blocks the retainer aperture 40 and thereby prevents insertion of the retainer stud 45 extending from the rear of the trip unit 17 as shown in Figure 4. The central groove 46 extending around the stud facilitates the retention of the trip unit by engaging the edges of the keyhole slot when the tab 39A is moved in the indicated direction and to move the slide 39 to the position shown in Figure 3B whereby the slide no longer blocks the retainer aperture 40 and the retainer stud can be inserted. The slide returns to the lock-out position of Figure 3A under the return bias provided by the stretched extension spring 53 when the tab 39A is released. In the event that the circuit breaker is not operational when an attempt is made to remove the retainer stud 45 within the retainer aperture and the slide 39 is in the interlock position of Figure 3A, a lever 44 shown in phantom, contacts retainer tab 39A extending from the slide 39 and prevents the slide from being moved to the position of Figure 3B. Withdrawal of the lever from the retainer tab readily allows the slide to be moved to the position of Figure 3B to allow the retainer stud to be removed from the retainer aperture 40 to remove the trip unit to the accessory-trip unit support 29 and thereby allow the trip unit to be interchanged only when the circuit breaker is in the de-energized position.

The bell alarm and lock-out unit 22A is shown in Figure 5 as one example of an accessory unit that is retained within the accessory housing 31 of

Figure 2. As described within the aforementioned U . S . Patent Appl ication Serial No . ( 41PR7175 ) entitled "Bell Alarm and Lock-out Accessory for a Digital Circuit Interrupter" , the trip indicating and reset button 22B interacts with the f lux shifter 49 to signal a trip occurrence as well as providing means to allow the circuit breaker operating mechanism to be reset . The plunger 15 extending from the bottom of the flux shifter and prevents the circuit breaker operating mechanism from being turned on unless the button 22B is depressed. The position of the rejection pin 48 extending from the bottom of the bell alarm and lock-out accessory shown in Figure 5 is keyed relative to a rejection aperture 51 formed in the bottom support plate 52 of Figure 2 to insure that a proper accessory unit is received within the associated accessory compartment 32 and that the contacts 54 ( Figure 5 ) on the bel l alarm and lock-out accessory connector 55 ( F igure 5 ) e lectrica l ly connect with the correspond i ng receptacles 28 on the bottom of the recess 24 shown in Figure 2.