Indicating fuse block

Abstract

An indicating fuse assembly includes an electrically non-conductive housing; an array of first and second electrically conductive contacts supported by the housing, each pair of first and second contacts being adapted for connecting a replaceable fuse, the contacts being connected in a powered circuit wherein each fuse, when connected between a respective pair of the contacts, is electrically series-connected with a load of the circuit; and a plurality of illuminators electrically connected within the housing for displaying open circuit conditions of corresponding ones of the fuses when the contacts are connected in the powered circuit, electrical current in the illuminators being limited to a minor fraction of a rated current of the corresponding loads. At least some the illuminators can include bipolar pairs of light emitting diodes for activation of the respective illuminators without regard to polarity of the circuit. In a preferred configuration, the assembly also includes a detector driver circuit for sensing activation of any of the illuminators, the detector driver circuit being adapted for signalling signaling an external circuit. The detector driver circuit can be configured for independently sensing a voltage across each fuse for driving the illuminators with current not flowing in the loads.

Description

RELATED APPLICATION

This application is a continuation-in-part of application Ser. No. 08/367,394, filed on Dec. 30, 1994, from a variety of sources, being rated at 1/4 watt per element. Thus any or all of the elements can safely drive corresponding ones of the illuminators 28 simultaneously at 10 ma.

As further shown in FIGS. 1-3 and 5, a preferred configuration of the fuse assembly 10 includes a detector driver 50 for driving an external indicator 52 whenever any of the illuminators 28 is activated. The detector driver 50 has at least one power connection 54, an exemplary configuration of the driver 50 having power connections designated 54B and 54C in FIG. 1, input connections 56 that are associated with particular ones of the power connections 54, and an output connection 58 to the indicator 52. The power connection 54B is to the main conductor 30B, and the power connections 54C are to respective ones of the auxiliary conductors 30C, the input connections 56 being made to respective ones of the second contacts 18B for the fuses 16 that are powered from corresponding ones of the supply conductors 30, the fuses 16 that are powered from the conductors 30A and 30B being grouped together. The detector driver 50 includes, for each power connection 54, a bipolar transistor having an emitter connection to the power connection 54, a base connection through respective logic diodes 60 to corresponding ones of the input connections 56, and a common collector connection through a current limiting resistor 62 to the output connection 58. Thus the common collector connection is driven toward the potential of the power connection 54B whenever any one of the illuminators 28 is activated.

As further shown in FIGS. 2-4, the housing 14 includes an upper housing 14A and a lower housing 14B, the illuminators 28, the resistor array 40, and the detector driver 50 being associated with the upper housing 14A, the contacts 18 and the supply conductors 30 being associated with the lower housing 14B. The housing portions 14A and 14B can be fixably connected by any suitable means (not shown) including screw fasteners and adhesive bonding. Also associated with the upper housing 14A are a plurality of network conductors 64 between the resistance connections 44 and respective ones of the illuminators 28, input conductors 66 between the second contacts 18B and respective ones of the input connections 56, and power conductors 68 between respective ones of the power connections 54 (and the bus connection 42) and corresponding ones of the first contacts 18A. As best shown in FIG. 3, the connections to the resistor array 40 and the detector driver 50 are implemented by respective double spring loops 70 that are formed for grippingly receiving corresponding lead pins of the associated devices. The connections to the contacts 18 are similarly implemented by single spring loops 72 that are biasingly retained between the associated contact 18 and the lower housing 14B. Connections to the illuminators 28 are effected by forked formations 74 of the respective conductors 64 and 66 that grippingly receive corresponding leads 48 of the illuminators 28. In the configuration of FIGS. 2-4, the resistor array 40 and the detector circuit 50 project slightly above the housing 14, for facilitating possible replacement of the resistor array 40 and the detector driver 50. Alternatively, either or both of these components can be partially of fully enclosed within the housing 14 for enhanced immunity from environmental factors.

With further reference to FIG. 6, an alternative configuration of the fuse assembly, designated 10', provides independent voltage detection for open-circuit conditions of the various fuses 16. A counterpart of the detector driver, designated 50', includes a separate voltage comparator 76 for each of the fuses 16, each of the comparators 76 having a reference voltage input (+) and an input (-) from a counterpart of the input connection, designated 56', each of the connections 56' being made to a corresponding second contact 18B. The voltage comparators 76 are configured for sinking current for the illuminators 28, the detector driver 50' incorporating current limiting means 40' and corresponding counterparts of the resistance connections, designated 44'. The connections 44' are to respective cathodes of the illuminators 28, the anodes thereof being connected to corresponding first contacts 18A of the fuses 16. The a reference voltage divider for the comparators 76 that are associated with the fuses 16 on the primary conductor 30A and the main conductor 30B are fed from the conductor 30B through the power connection 54B. However, counterpart circuits associated with the fuses 16 on the secondary conductors 30C are fed from the corresponding power connections 54C for preventing false activation of the associated comparators 76 when the corresponding load switches 36 are open. The detector driver 50' also includes a multiple-input OR gate 78 that is responsive to each of the comparators 76 and having current source capability for feeding the external indicator 52 through the limiting resistor 62 whenever any of the comparators 76 are activated. The principal advantage of this configuration of the fuse block 10' is that the loads 38 are not required to sink the drive current of the respective illuminators 28. The comparators 76 can have a very high input impedance so that the presence of substantially any load conductivity within a particular load 38 is effective for causing illumination of the respective illuminator 28 when the corresponding fuse 16 is open, provided only that the main switch 34 is closed (and in appropriate cases, the associated load switch 36 is also closed). Another advantage is that the function of the resistor array 40 is incorporated within the detector driver 50', thereby simplifying packaging of the fuse block 10'. It will be understood that separate source current connections and reference voltage dividers can be provided for each of the voltage comparators 76, so that a single configuration of the detector driver 50' having a sufficient number of the comparators 76 can be used regardless of the number of secondary conductors 30C and fuses 16 associated therewith.

With further reference to FIG. 7, another alternative configuration of the fuse assembly 10 has a single resistor 40" connected between the supply conductor 30 and a limiting conductor 42', a plurality of the illuminators 28 being connected between the limiting conductor 42' and respective ones of the second contact 18B. In this embodiment of the present invention, the illuminators 28 will always be activated within the range of 5 ma to 20 ma, assuming that there is no "current hogging" when the resistor 40" is selected for powering a single illuminator 28 at 20 ma, as long as the battery 32 provides 14 volts, the load circuits have resistances that are insignificant relative to the resistance of the resistor 40", and not more than four of the illuminators 28 are activated at a time. Similarly, with the battery 32 supplying 12 volts, three of the illuminators 28 would be activated at (12-1.4)v/(3)630 ohms=5.6 ma. With four of the illuminators 28 activated, the average current drops to 4.2 ma, and the resistor 40" dissipates [(14-1.4)v]² /630=0.252 watts at full voltage. Thus the resistor 40" can be appropriately configured for a power rating of 1/2 watt. It will be understood that in the configuration of FIG. 6, the use of incandescent lamps or bipolar LEDs would be inappropriate due to shorting current paths between the illuminators 28.

Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. For example, the resistor network 40 (or the resistor 40") can be selected for other current limitations and/or for use in circuits having other voltages. Also, each illuminator 28 can be provided as a flashing LED for reduced power dissipation by the resistor array 40 (or the resistor 40"), and for attracting the attention of those monitoring the fuse assembly 10. Moreover, a LED having an integral resistor can be substituted in the configurations of FIGS. 1-6. An LED having an integral resistor and suitable for the present invention is available as 2RD-xxx from Dialight of Manasaquan, N.Y. The detector driver 50' can incorporate low current sources for biasing the fuses 16 that are fed from the secondary conductors 30C, for providing visual indications of fuse failure even when the corresponding circuitry is unpowered. In the circuit configuration of FIG. 5, the resistor array 40 can be combined with the detector driver 50. Therefore, the spirit and scope of the appended claims should not necessarily be limited to the description of the preferred versions contained herein.

Claims

1. An indicating fuse assembly comprising:

(a) a housing formed of an electrically non-conductive material;

(b) an array of first and second electrically conductive contact members extending within the housing for support thereby, each pair of first and second contact members being adapted for connecting a replaceable fuse;

(c) means for connecting the contact members in a powered circuit wherein each fuse, when connected between a respective pair of the contact members, is electrically series-connected with a load of the circuit, each load having a rated current, at least some of the first contact members of the array being powered independently of others of the first contact members;

(d) a plurality of illuminators electrically connected within the housing for displaying open circuit conditions of corresponding ones of the fuses when the contact members are connected in the powered circuit, one side of each illuminator being connected to a respective second contact member of the array;

(e) means for limiting electrical current in the illuminators to a minor fraction of the rated current of the corresponding loads; and

(f) a detector driver circuit for sensing activation of any of the illuminators, the detector driver circuit being adapted for signalling signaling an external circuit, the detector driver circuit including means for preventing false activation of the external circuit in the event that only a subset of the first contact members are powered.

2. The fuse assembly of claim 1, wherein at least some of the illuminators comprise light emitting diodes.

3. The fuse assembly of claim 2, wherein the means for limiting comprises a resistor element series-connected with each illuminator.

4. The fuse assembly of claim 3, wherein the illuminators and the series resistor elements are supported within the housing.

5. The fuse assembly of claim 2, wherein at least some the illuminators comprise bipolar pairs of light emitting diodes for activation of the respective illuminators without regard to polarity of the circuit.

6. The fuse assembly of claim 1, wherein the means for limiting current comprises a single resistance element in series with a common connection to a plurality of the illuminators.

7. The fuse assembly of claim 1, wherein the detector driver circuit is operative for activating a current source to the external circuit for driving a current load thereof.

8. An indicating fuse assembly comprising:

(a) a housing formed of an electrically non-conductive material;

(b) an array of first and second electrically conductive contact members extending within the housing for support thereby, each pair of first and second contact members being adapted for connecting a replaceable fuse;

(c) means for connecting the contact members in a powered circuit wherein each fuse, when connected between a respective pair of the contact members, is electrically series-connected with a load of the circuit, each load having a rated current;

(d) a plurality of illuminators electrically connected within the housing for displaying open circuit conditions of corresponding ones of the fuses when the contact members are connected in the powered circuit;

(e) means for limiting electrical current in the illuminators to a minor fraction of the rated current of the corresponding loads; and

(f) a detector driver circuit for sensing activation of any of the illuminators, the detector driver circuit being adapted for signalling an external circuit, the detector driver circuit comprising a comparator circuit for comparing a voltage of each load with a reference voltage, activation of the corresponding illuminator being responsive to operation of the comparator circuit, the illuminator being driven by current not required to flow within the load.

9. The fuse assembly of claim 8, wherein at least some of the illuminators comprise light emitting diodes.

10. The fuse assembly of claim 9, wherein the means for limiting comprises a resistor element series-connected with each illuminator.

11. The fuse assembly of claim 10, wherein the illuminators and the series resistor elements are supported within the housing.

12. The fuse assembly of claim 9, wherein at least some the illuminators comprise bipolar pairs of light emitting diodes for activation of the respective illuminators without regard to polarity of the circuit.

13. The fuse assembly of claim 8, wherein the means for limiting current comprises a single resistance element in series with a common connection to a plurality of the illuminators.

14. The fuse assembly of claim 8 15, wherein the detector driver circuit is operative for activating a current source to the external circuit for driving a current load thereof.

15. The fuse assembly of claim 8, further comprising a detector driver circuit for sensing activation of any of the illuminators, the detector driver circuit being adapted for signaling an external circuit in response to operation of the comparator circuit.