Electronic circuit breaker systems

Claim 2

An electronic circuit breaker for preventing damage to a load from overload conditions while minimizing downtime after cessation of such a condition, comprising in combination: means for interrupting flow of overload currents to the load, including means for instantaneously reducing electric current flow from a power supply to the load to a harmless residual current when that electric current flow exceeds a predetermined value; means for sensing said overload currents; means for connecting at least part of said means for sensing said overload currents and said means for interrupting flow of overload currents in series in a main electric current path to the load; means connected to said electric current flow reducing means for electronically monitoring said residual current; means connected to said monitoring means for indicating when it is safe to restore electric operating current flow to the load; and means for restoring flow of electric operating current from the power supply to the load in response to the latter indication.

Claim 3

Apparatus as claimed in claim 1, wherein: said electric current flow reducing means and said restoring means include means connected to said monitoring means for automatically switching said electronic circuit breaker and flow of electric operating current back on in response to said indication.

Claim 4

Apparatus as claimed in claim 1, wherein: said electric current flow reducing means include a field-effect transistor for switching the electric current flow between the power supply and the load; and said electric operating current flow restoring means include means connected to said field-effect transistor for switching said field-effect transistor to an electric current conducting state in response to said indication.

Claim 5

Apparatus as claimed in claim 3, wherein: said electric current flow reducing means include means connected to said field-effect transistor for driving said field-effect transistor to a nonconducting state when said electric current flow exceeds said predetermined value; and means for providing a current flow path acting in parallel to said field effect transistor and being of sufficient impedance for said reduction of electric current flow to a harmless residual current when said field effect transistor is driven to said non-conducting state.

Claim 6

Apparatus as claimed in claim 3, wherein: at least part of said means for sensing said overload currents is connected in said main electric current path in series with said field-effect transistor.

Claim 7

Apparatus as claimed in claim 1, wherein: said electric current flow reducing means include a current sensing field-effect transistor for switching the electric current flow between the power supply and the load and for sensing when said electric current flow exceeds said predetermined value, and means connected to said current sensing field-effect transistor to a non-conducting state in response to said sensing; and said electric operating current flow restoring means include means connected to said current sensing field-effect transistor for switching said current sensing field-effect transistor to an electric current conducting state in response to said indication.

Claim 8

Apparatus as claimed in claim 1, wherein: said electric current flow reducing means include means for providing a current flow path acting in parallel to said current sensing field-effect transistor and being of sufficient impedance for said reduction of electric current flow to a harmless residual current when said current sensing field-effect transistor is driven to a non-conducting sate in response to said sensing.

Claim 9

Apparatus as claimed in claim 1, wherein: said monitoring means include means for setting a value for said residual current indicative of a return of said load to a normal operating condition, and means connected to said setting means for sensing a decrease of said residual current to at least as low as said value; and said electric operating current flow restoring means include means connected to said sensing means for restoring said flow of electric operating current in response to said sensing.

Claim 10

Apparatus as claimed in claim 1, wherein: said means for electronically monitoring include means connected to the load for electronically monitoring voltage drop variations across the load.

Claim 11

Apparatus as claimed in claim 1, wherein: said means for restoring flow of electric operating current include means for preventing malfunction of said means for indicating when it is safe to restore electric operating current, said malfunction preventing means include means for preventing flow of electric operating current at least for a period of time corresponding to a discharge time of a capacitive component of the load.

Claim 12

Apparatus as claimed in claim 1, including: means for switching said circuit breaker off and for alternatively resetting said circuit breaker.

Claim 13

Apparatus as claimed in claim 11, wherein: said indicating means include means for indicating to an operator of said switching means when it is safe to reset said circuit breaker.

Claim 14

Apparatus as claimed in claim 1, including: means connected to said electric current flow reducing means for indicating when said circuit breaker has tripped.

Claim 15

An electronic circuit breaker for preventing damage to a load from overload conditions while minimizing downtime after cessation of such a condition, comprising in combination: means for interrupting flow of overload currents to the load, including means for instantaneously reducing electric current flow from a power supply to the load to a harmless residual current when that electric current flow exceeds a predetermined value; means connected to said electric current flow reducing means for electronically monitoring said residual current; means connected to said monitoring means for indicating when it is safe to restore electric operating current flow to the load; means for restoring flow of electric operating current from the power supply to the load in response to the latter indication, including means for resetting said circuit breaker; means for switching said circuit breaker off; and means for remotely locating from said circuit breaker said means for switching the circuit breaker off and said means for resetting said circuit breaker.

Claim 16

An electronic circuit breaker for preventing damage to a load from overload conditions while minimizing downtime after cessation of such a condition, comprising in combination: means for interrupting flow of overload currents to the load, including means for instantaneously reducing electric current flow from a power supply to the load to a harmless residual current when that electric current flow exceeds a predetermined value; means connected to said electric current flow reducing means for electronically monitoring said residual current; means connected to said monitoring means for indicating when it is safe to restore electric operating current flow to the load; means for restoring flow of electric operating current from the power supply to the load in response to the latter indication, including means for resetting said circuit breaker; means for switching said circuit breaker off; and means for remotely locating from said circuit breaker said means for switching the circuit breaker off and said means for resetting said circuit breaker.

Claim 17

Apparatus as claimed in claim 14, including: means connected to said monitoring means for indicating at said resetting means when it is safe to reset said circuit breaker.

Claim 18

Apparatus as claimed in claim 14, wherein: said resetting means include means for overriding said means for instantaneously reducing electric current flow during a resetting action; and said means for interrupting flow of overload currents include said means for instantaneously reducing electric current flow after said resetting action.

Claim 19

Apparatus as claimed in claim 14, including: means for sensing said overload currents; and means for connecting at least part of said means for sensing said overload currents and said means for interrupting flow of overload currents in series in a main electric current path to the load.

Claim 20

An electronic circuit breaker for safeguarding electronic equipment connected to a power supply against damage from overload conditions while avoiding downtime after cessation of such a condition, comprising in combination: first and second interconnected bistable devices each having a first switching state and an alternative second switching state; means connected to the first bistable device and between the power supply and the electronic equipment for supplying electric operating current to the electronic equipment when the first bistable device is in its first switching state and the second bistable device is in its second switching state; means connected to the first and second bistable devices for switching the first bistable device to its second switching state and the second bistable device to its first switching state in response to an overload condition; means connected to said switching means and to said electric operating current supplying means for interrupting supply of operating current to the electronic equipment in response to said switching of the first bistable device to its second switching state; means connected to the first bistable device for latching the first bistable device in its second switching state when the second bistable device is in its first switching state; means connected to the load for indicating a cessation of the overload condition; means connected to the second bistable device and to said indicating means for returning the second bistable device to its second switching state in response to the latter indication of a cessation of the overload condition; and means connected to the first bistable device for suspending said latching when the second bistable device reverts to its second switching state and for returning the first bistable device to its first switching state whereby supply of electric operating current to the electronic equipment is resumed when the overload condition has ceased.

Claim 21

An electronic circuit breaker for safeguarding electronic equipment connected to a power supply against damage from overload conditions while avoiding downtime after cessation of such a condition, comprising in combination: first and second interconnected bistable devices each having a first switching state and an alternative second switching state; means connected to the first bistable device and between the power supply and the electronic equipment for supplying electric operating current to the electronic equipment when the first bistable device is in its first switching state and the second bistable device is in its second switching state; means connected to the first and second bistable devices for switching the first bistable device to its second switching state and the second bistable device to its first switching state in response to an overload condition; means connected to said switching means and to said electric operating current supplying means for interrupting supply of operating current to the electronic equipment in response to said switching of the first bistable device to its second switching state; means connected to the first bistable device for latching the first bistable device in its second switching state when the second bistable device is in its first switching state; means connected to the load for indicating a cessation of the overload condition; means connected to the second bistable device and to said indicating means for returning the second bistable device to its second switching state in response to the latter indication of a cessation of the overload condition; and means connected to the first bistable device for suspending said latching when the second bistable device reverts to its second switching state and for returning the first bistable device to its first switching state whereby supply of electric operating current to the electronic equipment is resumed when the overload condition has ceased.

Claim 22

Apparatus as claimed in claim 18, including: means connected to the first and second bistable devices for automatically suspending said latching with the second bistable device returning to its second switching state for said return of the first bistable device to its first switching state.

Claim 23

Apparatus as claimed in claim 18, wherein: said means for switching the first bistable device to its second switching state and the second bistable device to its first switching state in response to an overload condition include means connected to said electronic equipment for switching said second bistable device only to that second switching state when a voltage across said electronic equipment has diminished to a negligible value.

Claim 24

Apparatus as claimed in claim 20, including: a component in said electronic equipment imposing a time delay on a diminution of said voltage to a negligible value; and means connected to the first bistable device for latching the first bistable device in its second switching state for a period of time corresponding to said time delay.

Claim 25

Apparatus as claimed in claim 18, wherein: said means for indicating a cessation of the overload condition include means for electronically monitoring voltage drop variations across said electronic equipment; and said means for returning the second bistable device to its second switching state include means connected to said means for electronically monitoring said voltage drop variations for returning the second bistable device to its second switching state when said monitoring indicates a cessation of the overload condition.

Claim 28

A method as claimed in claim 23, wherein: said monitored residual current is used for automatically switching said electronic circuit breaker and flow of electric operating current electronically back on when said monitoring has determined that the overload condition has ceased to exist.

Claim 29

A method as claimed in claim 23, including the steps of: providing a field-effect transistor for switching the electric current flow between the power supply and the load; reducing said electric current flow with the aid of said field-effect transistor; and restoring said flow of electric operating current with said field-effect transistor.

Claim 30

A method as claimed in claim 25, wherein: said sensing includes sensing said overload currents in said main current path in series with said field-effect transistor.

Claim 31

A method as claimed in claim 25, including the step of: providing a current flow path acting in parallel to said field-effect transistor and being of sufficient impedance for said reduction of electric current flow to a harmless residual current when said field-effect transistor is driven to a non-conducting state.

Claim 32

A method as claimed in claim 27, including the step of: driving said field-effect transistor to said non-conducting state in response to said electric current flow exceeding said predetermined value.

Claim 33

A method as claimed in claim 23, including the steps of: providing a current sensing field-effect transistor for switching the electric current flow between the power supply and the load; sensing with the aid of said current sensing field-effect transistor when said electric current flow exceeds said predetermined value; reducing said electric current flow in response to said sensing with the aid of said current sensing field-effect transistor; and restoring said flow of electric operating current with said current sensing field-effect transistor.

Claim 34

A method as claimed in claim 29, including the step of: providing a current flow path acting in parallel to said current sensing field-effect transistor and being of sufficient impedance for said reduction of electric current flow to a harmless residual current when said current sensing field-effect transistor is driven to a non-conducting state in response to said sensing.

Claim 35

A method as claimed in claim 29, wherein: said determination includes the steps of setting a value for said residual current indicative of a return of said electronic equipment to a normal operating condition, and sensing a decrease of said residual current to at least as low as said value; and said flow of electric operating current is restored in response to said sensing.

Claim 36

A method as claimed in claim 23, including the step of: indicating when said circuit breaker has tripped.

Claim 37

A method as claimed in claim 23, including the step of: indicating when it is safe to reset said circuit breaker.

Claim 40

A method as claimed in claim 34, including the step of: extending said monitoring to indicate at said remote location when it is safe to reset said circuit breaker.

Claim 41

A method as claimed in claim 34, including the steps of: suspending during resetting of said circuit breaker said instantaneous reducing of electric current flow; and reinstating after each resetting an interruption of an overload current flow to the load.

Claim 42

A method as claimed in claim 34, including the steps of: providing said circuit breaker with a main electric current path; connecting said circuit breaker with said main current path between a power source selected from the group of voltage regulated, current regulated and other electric power sources, and said load; sensing overload currents in said main current path; and interrupting flow of current to the load as a function of overload current irrespective of source voltage variation by instantaneously reducing electric current flow from a power supply to the load to a harmless residual current when that electric current flow exceeds a predetermined value.

Claim 45

A method as claimed in claim 38, including the step of: automatically suspending said latching with the second bistable device returning to its second switching state for said return of the first bistable device to its first switching state.

Claim 46

A method as claimed in claim 38, wherein: said second bistable device is only switching to its second switching state when a voltage across said electronic equipment has diminished to a negligible value.

Claim 47

A method as claimed in claim 40, wherein: a component in said electronic equipment imposes a time delay on a diminution of said voltage to a negligible value; and said first bistable device is latched in its second switching state for a period of time corresponding to said time delay.

Claim 48

A method as claimed in claim 38, including the steps of: electronically monitoring voltage drop variations across said electronic equipment; and returning the second bistable device to its second switching state when said monitoring indicates a cessation of the overload condition.

Claim 49

An electronic circuit breaker for preventing damage to a load from overload conditions while minimizing downtime after cessation of such a condition, comprising in combination: means for interrupting flow of overload currents to the load, including means for instantaneously reducing electric current flow from a power supply to the load to a harmless residual current when that electric current flow exceeds a predetermined value; means connected to said electric current flow reducing means for electronically monitoring said residual current; means connected to said monitoring means for indicating when it is safe to restore electric operating current flow to the load; and means for restoring flow of electric operating current from the power supply to the load in response to the latter indication, including means for preventing malfunction of said means for indicating when it is safe to restore electric operating current, said malfunction preventing means include means for preventing flow of electric operating current at least for a period of time corresponding to a discharge time of a capacitive component of the load.

Claim 50

An electronic circuit breaker for preventing damage to a load from overload conditions while minimizing downtime after cessation of such a condition, comprising in combination: means for interrupting flow of overload currents to the load, including means for instantaneously reducing electric current flow from a power supply to the load to a harmless residual current when that electric current flow exceeds a predetermined value; means connected to said electric current flow reducing means for electronically monitoring said residual current; means connected to said monitoring means for indicating when it is safe to restore electric operating current flow to the load; and means for restoring flow of electric operating current from the power supply to the load in response to the latter indication, including means for preventing malfunction of said means for indicating when it is safe to restore electric operating current, said malfunction preventing means include means for preventing flow of electric operating current at least for a period of time corresponding to a discharge time of a capacitive component of the load.