WO2008040054A1 - Circuit de commande - Google Patents

Circuit de commande Download PDF

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Publication number
WO2008040054A1
WO2008040054A1 PCT/AU2007/001470 AU2007001470W WO2008040054A1 WO 2008040054 A1 WO2008040054 A1 WO 2008040054A1 AU 2007001470 W AU2007001470 W AU 2007001470W WO 2008040054 A1 WO2008040054 A1 WO 2008040054A1
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WO
WIPO (PCT)
Prior art keywords
terminal
mode
voltage
control circuit
relay
Prior art date
Application number
PCT/AU2007/001470
Other languages
English (en)
Inventor
Wayne Callen
Richard Leslie Brissenden
Robert Keith Henry Smith
Original Assignee
Protectelec Pty Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2006905493A external-priority patent/AU2006905493A0/en
Application filed by Protectelec Pty Limited filed Critical Protectelec Pty Limited
Publication of WO2008040054A1 publication Critical patent/WO2008040054A1/fr

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/14—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to occurrence of voltage on parts normally at earth potential

Definitions

  • the present invention relates to a control circuit and a method of control.
  • the invention has been developed primarily for use with a non-MEN electrical distribution system, and will be described hereinafter with reference to that application. However, the invention is not limited to that particular field of use and is suitable for use in conjunction with an MEN electrical distribution system.
  • an MEN distribution system for example, a public mains utility such as is in common usage worldwide - is not available it is known to use a power source in the form of an electrical generator or an inverter to provide a voltage signal similar to that provided by the mains supply. This allows the use of mains powered appliances notwithstanding the absence of a mains utility.
  • the power from this generator or inverter is distributed, by a distribution system that is isolated from the MEN system, to the one or more electrical loads. While some of these distribution systems are earthed - in that they include at least one earth-stake or earth-pin - in the case of marine and aircraft applications that will not be so.
  • the isolated power sources include, for example in higher power applications, a diesel engine driven generator and, for example in lower power applications, a DC-to-AC inverter.
  • a diesel engine driven generator and, for example in lower power applications, a DC-to-AC inverter.
  • a DC-to-AC inverter By way of a particular example, it is known to mount an inverter to a service vehicle, where the inverter uses as an input the 12 Volt DC source of the vehicle.
  • the typical output of these types of inverters is 110 Volts AC or 240 Volts AC at either 50 Hz or 60 Hz respectively.
  • the output of an inverter is usually an approximation of a true sinusoidal signal and, depending upon the inverter, can include considerable noise.
  • Inverters may only provide a square wave, or a minimally smoothed square wave.
  • Inverters supply relatively high voltages, in that those voltages are above what is considered to be a safe touch-potential of about 50 Volts. This being so, it is necessary, at least in some jurisdictions, for inverters to include an earth-stake that is "grounded" while the inverter is operational. This is an attempt to replicate the earth connection used in the MEN system. However, in practice, this grounding rarely happens due to the inconvenience of doing so, and the fact that in the absence of a fault condition the inverter appears to function normally.
  • Power sources that are isolated from the MEN system are more susceptible than power supply utilities to voltage and frequency fluctuations with time. This is due not only to the requirement for accurate inputs demanded by the regulators of the utilities, but also because of the much smaller size of the isolated systems. Accordingly, the isolated systems are more open to influence from localized factors such as temperature, load, vagaries in the distribution system, and the like. Particularly with solid-state inventers (such as switch-mode inverters) there are often considerable transient voltages generated that can interfere with mains operated devices that are being powered by the inverter. The mains operated devices often include protection circuitry or sensitive control and regulating circuitry, both of which can be either falsely triggered or rendered inoperative.
  • these protection circuits and control circuits are designed for more consistent and less noisy operating voltages such as those provided by a mains utility. Additionally, the use of inverters under fault conditions can render some safety devices inoperable, hence negating the only reason for including the safety device in the first place. This makes it more difficult for conventional protection circuits to adequately protect inventers.
  • a control circuit for an inverter that provides an AC voltage between at least one phase terminal and a neutral terminal
  • the control circuit including: at least two input terminals, one for electrically connecting with the phase terminal and another for electrically connecting with the neutral terminal; at least two output terminals, one for electrically connecting with a load terminal of an electrical load and another for electrically connecting the load with the neutral terminal; a detector for providing a fault signal in response to a fault condition; and a switching device that is responsive to the fault signal for progressing between a first mode and a second mode wherein: in the first mode the input and output termirials are electrically connected for allowing the load terminal to receive the AC voltage from the phase terminal via the switching device; and in the second mode the input and output terminals are electrically disconnected for preventing the phase terminal from supplying the AC voltage to the
  • AC voltage provided by the inverter is usually an approximation of a true sinusoidal signal. Depending upon the inverter the AC voltage can include considerable noise. Some inverters, particularly those at the lower quality and price, may only provide a square wave, or a minimally smoothed square wave. In this specification, unless the context clearly indicates otherwise, the term AC voltage is intended to encompass all such outputs of inverters.
  • the inverter is powered by a DC source of a predetermined voltage, and the AC voltage is greater than the predetermined voltage.
  • the predetermined voltage is one of: 12 Volts, 24 Volts, 42 Volts and 48 Volts. In other embodiments, however, alternative predetermined voltages are used.
  • the predetermined voltage changes over time.
  • the AC voltage is at 50 Hz and 240 Volts, while in other embodiments alternative frequencies and voltages are provided, such as 60 Hz and 110 Volts.
  • the detector includes a detector relay.
  • the detector relay is a low voltage armature relay. More preferably, the detector relay is a small signal (or telecom-type) relay.
  • the detector includes a small signal relay having a typical coil/switching voltage of between about 3 to 6 Volts. The switching voltage is that voltage at which the detector relay will change state: that is, the voltage at which the relay will switch.
  • An example of a suitable small signal relay is sold with the branding "Nashua NEC", and marked with Model number D005-M. For such a relay the typical coil resistance is about 50 Ohms to 300 Ohms.
  • the detector includes a solid-state relay.
  • the detector relay has a detector relay coil and a detector relay armature that moves between two sets of contacts.
  • the detector relay coil is not energized and the detector relay armature is engaged with a first of the two sets of contacts. More preferably, once the fault condition appears the detector relay coil is energized and the detector relay armature moves into engagement with the other set of contacts. Even more preferably, once the fault condition is removed the detector relay coil is de-energized and the detector relay armature returns to engage with the first set of contacts.
  • the switching device is a switching relay.
  • the switching relay is a mains-rated relay. More preferably, the switching relay is a cradle relay rated at 250 Volts and 12 Amps, and has a typical coil voltage of 250 Volts.
  • the switching relay is a "Finder Type 56.32” which is rated at 250 Volts and 12 Amps.
  • Another suitable switching relay is "Tianbo Model number HJQ/13F/2ZP" which is rated at 240 Volts and 10 Amps.
  • a further example product suitable for use as the switching relay is sold with the branding "Nais HL2-L- AC240" and which is rated at 240 Volts and 10 Amps.
  • a further example product suitable for use as the switching relay is sold by IMO Precision Controls Limited and designated as SRP-1C1N-SL-230VAC and which is rated at 250 VAC and 16 Amps.
  • the switching relay has a switching relay coil and a switching relay armature that moves between two sets of contacts. Preferably, in the absence of the fault condition, the switching relay coil is not energized and the switching relay armature is engaged with a first of the two sets of contacts.
  • a protection device for an inverter including: at least one control circuit of the first aspect; and a housing for encapsulating the control circuit.
  • the detector includes a detector relay for providing the fault signal
  • the switching device includes a switching relay that is responsive to the fault signal for moving between a first state and a second state that correspond with the first mode and the second mode.
  • the detector relay includes a detector relay coil and the switching relay includes a switching relay coil both of which, in the absence of a fault, are not energized.
  • a control circuit for a generator device that provides an AC voltage between at least one phase terminal and a neutral terminal
  • the control circuit including: an input terminal for electrically connecting with the phase terminal; an output terminal for electrically connecting with a load terminal of an electrical load wherein, in use, the electrical load is also electrically connected with the neutral terminal; a detector for providing a fault signal in response to a fault condition; and a switching device that is responsive to the fault signal for progressing between a first mode and a second mode wherein: in the first mode the input and output terminals are respectively electrically connected for allowing the load terminal to receive the AC voltage from the phase terminal via the switching device; and in the second mode the input and output terminals are electrically disconnected for preventing the phase terminals from supplying the AC voltage to the load terminal via the switching device.
  • the generator device includes one of: an inverter; and a generator. That is, a generating device converts energy of one form to an AC electrical signal.
  • An inverter for example, converts energy in the form of a DC voltage - typically from an electrochemical cell or cells or from a vehicular alternator - into an AC voltage signal.
  • a generator converts rotational energy into an AC voltage. In other embodiments other forms of energy are converted to an AC voltage.
  • a combination of types of energy is converted into the AC voltage. It will also be appreciated that the AC signal generated by an inverter will be an approximation of a mains AC electrical signal.
  • the detector provides the fault signal while the fault condition persists, and the switching device remains in the second mode while the fault signal persists.
  • the switching device remains in the second mode until reset. More preferably, the switching device remains in the second mode until manually reset.
  • the switching device in progressing from the first mode to the second mode, progresses the detector from an enabled state to a disabled state.
  • the detector is progressed to the enabled state. That is, if the fault condition persists when the switching device progresses to the first mode in response to being reset, the detector, being in an enabled state, provides the fault signal and the switching device returns to the second mode.
  • the generator device is mounted to a support frame that is electrically isolated from the terminals, and the detector is electrically connected to the frame. More preferably, the frame defines, at least in part, a housing for the generator device. In some embodiments, the frame and housing are integrally formed.
  • the control circuit is mounted to the housing. More preferably, the control circuit is mounted within the housing. Even more preferably, the generator terminal is disposed within the housing and the output terminal is accessible from outside the housing. For example, in some embodiments, the output terminal extends beyond the housing. However, in other embodiments, the output terminal is a female terminal that is accessible for contact with a complementary male terminal. In these embodiments only the output terminal is accessible from outside the housing and not the generator terminal. In other embodiments, the generator terminal is also accessible from outside the housing. [0031] In an embodiment, the neutral terminal is accessible from outside the housing.
  • the frame or housing is conductive and the neutral terminal is electrically connected to the frame or housing, wherein the detector is electrically connected to an element that is electrically isolated from the frame or housing and which, in use, is isolated from the AC voltage.
  • the frame or housing is conductive and the neutral terminal is electrically connected to the frame or housing and the detector is connected to an element that is electrically connected to the housing, wherein the resistance of the element is sufficient to allow a fault voltage to be generated in the presence of a fault current.
  • the generator device is, in use, mounted to a conveyance and the detector is electrically connected to an element of the conveyance that, in use, is electrically isolated from the generator terminal.
  • the element is conductive.
  • the conveyance is a vehicle having a conductive body and the element is defined by the body.
  • the neutral terminal is referenced to the body, and the detector is electrically connected to a further element of the conveyance.
  • the conductive body is a chassis of the vehicle, while in other embodiments the conductive body is a frame or a panel of the vehicle.
  • the vehicle is self-propelled and is, for example, a truck, an SUV, a van or other motor vehicle.
  • the vehicle is not self- propelled and is, for example, a trailer.
  • different vehicles are used, for example, an aircraft, a glider, a boat, a ship, a motorbike, a motor scooter, or the like.
  • the conveyance includes a DC power source and the generator device is connected to the DC power source for providing the AC signal. More preferably, the DC power source includes a positive terminal and a negative terminal, wherein the negative terminal and one of the terminals of the generator device are electrically connected to the conveyance.
  • a control circuit including: an input terminal for electrically connecting with a power source that, in use, provides a source voltage; an output terminal for electrically connecting with a load; a detector having: an input that, in use, is connected to the power source; and an output, wherein the detector is responsive to a reference signal being within a predetermined range for electrically connecting the input and the output to apply the source voltage to the output; and a switching device that is electrically connected to the output of the detector and which is responsive to the source voltage being applied to the output for progressing between a first mode and a second mode wherein: in the first mode the input terminal and the output terminal are electrically connected for allowing the load to receive power from the source via the switching device; and in the second mode the input terminal and the output terminal are electrically disconnected for preventing the source from supplying power to the load via the switching device.
  • the detector includes a sensor relay having a sensor coil and a first sensor contact and a second sensor contact, wherein the sensor coil, when energized by the reference signal, connects the first sensor contact to the second sensor contact. More preferably, the first and second sensor contacts respectively define the input and the output.
  • the switching device includes a switching relay having: a switching coil that is electrically connected to the output; and a first switching contact and a second switching contact, wherein the switching coil, when energized by the source voltage at the output, progresses the switching device between the first mode and the second mode.
  • a control circuit for an electrical appliance having a load element for receiving electrical power from a power source having a floating earth, the appliance having at least one conductive element which is not, in use, electrically connected with the floating earth, the circuit including: at least two input terminals for electrically connecting with the power source; at least two output terminals for electrically connecting with the load element; a detector that is responsive to the voltage of the element for providing a reference signal; and a switching device being interposed between the input and output terminals and being responsive to the reference signal being within a predetermined range for progressing from a first mode to a second mode wherein: in the first mode the input and output terminals are respectively electrically connected for allowing the load element to receive power from the source via the switching device; and in the second mode the input and output terminals are electrically disconnected for preventing the source from supplying power to the load via the switching device.
  • the appliance is mounted to a conveyance having a body that is electrically connected with the floating earth.
  • a conveyance include an automobile, a watercraft, an aircraft, a motorbike, a trailer and the like.
  • the appliance is mounted to a structure such as a frame, a platform, a housing or other structure.
  • the power source is separate from the mains supply and is preferably a generator device. More preferably, the generator device is a generator — that is, a device that converts rotational energy into electrical energy such as an AC voltage — or an inverter - that is, a device that converts a DC voltage into an AC voltage.
  • the power source is mounted to the conveyance or the structure, as the case may be.
  • the appliance is a fluid pump.
  • the appliance is one or a combination of: the fluid pump; an electric drill; an electric motor; an iron; a hair dryer; a consumer white-good such as a refrigerator, a washing machine, a clothes dryer; a computer, be that a laptop computer or a desktop computer; a computer peripheral device or stand alone device such as a printer, modem, facsimile machine or the like; a piece of or combination of domestic hi-fi equipment; a television or associated hardware; a hot water kettle; or the like.
  • the control circuit is a protective device for electrically isolating the load from the power source once a fault condition has been detected.
  • Figure 1 is a schematic representation of a portable petrol-driven generator having a control circuit
  • Figure 2 is a schematic circuit diagram of the control circuit used in the embodiment of Figure 1;
  • Figure 3 is a schematic representation of a portable inverter including a control circuit
  • Figure 4 is a schematic representation of a further embodiment of the invention including a protection device
  • Figure 5 is a schematic representation of a three-phase generator including a control circuit
  • Figure 6 is a schematic side view of a vehicle to which is mounted the inverter of Figure 3.
  • Figure 7 is a schematic representation of a protection device applicable to the Figure 4 embodiment.
  • FIG. 1 there is provided a control circuit 1 for a generator device in the form of a portable 2 HP petrol-engine powered single-phase generator 2.
  • the generator provides a voltage of about 240 Volts AC between a phase terminal 3 and a neutral terminal 4.
  • Circuit 1 includes two input terminals 5 and 6 for electrically connecting with respective terminals 3 and 4, and two output terminals 7 and 8 for electrically connecting, via an electrical cable 9, with a load in the form of an electric motor 10.
  • a detector 11 provides a fault signal at its output 13 in response to a fault condition at its input 14.
  • a switching device 15 is responsive to the fault signal at output 13 for progressing between a first mode and a second mode wherein: in the first mode terminals 5 and 6 are respectively electrically connected to terminals 7 and 8 for allowing motor 10 to receive the AC voltage from terminals 3 and 4 via switching device 15; and in the second mode terminals 5 and 6 are respectively electrically disconnected to terminals 7 and 8 for preventing terminals 3 and 4 from supplying the AC voltage to motor 10 via switching device 15.
  • Generator 2 is designed to be portable, and to provide a convenient mains power source for powering electrical appliances or electrical equipment with mains voltages when the normal mains supply is not available. Generators of this type are used commonly on building sites, or carried on service vehicles, or the like.
  • the generator is powered by an alternative energy source such as a diesel engine, natural gas engine, or the otherwise.
  • generator 2 is a larger capacity generator for larger electrical loads, and is fixed in a given location.
  • Terminal 3 is a phase or active terminal
  • terminal 4 is a neutral terminal, with the result that in normal use terminal 7 is a phase terminal
  • terminal 8 is a neutral terminal.
  • cable 9 includes a phase conductor 17 and a neutral conductor 18.
  • generator 2 includes a greater number of phase terminals and a corresponding number of circuits 1 are used in conjunction with those terminals to provide corresponding protection.
  • circuit 1 is replaced by a single protection circuit with the requisite number of input terminals 5.
  • Figure 5 illustrates schematically a fixed location three-phase diesel generator 12, where corresponding features are denoted by corresponding reference numerals.
  • Generator 12 includes three separate phase terminals 3 - one for each of the phases of the three-phase supply being provided - and one neutral terminal 4."
  • Circuit 16 includes three input terminals 5, each for connecting with a respective phase terminal 3, and three output terminals 7 for connecting with respective loads. In other embodiments terminals 7 are all connected to the same three-phase load (not shown).
  • Generator 12 is designed to power larger loads, and is not portable but, rather, fixed in a given location. In other embodiments generator 12 is designed to power devices such as welders or portable lighting towers that are relatively large and difficult to move but portable nonetheless.
  • generator 2 is disposed, together with circuit 1, in a ventilated prismatic sheet metal generator housing 19.
  • the function of housing 19 is primarily to protect generator 2 from the elements, and to reduce the risk of inadvertent or unauthorised access to or contact with generator 2 and the terminals.
  • This housing is electrically isolated from all the terminals and, in the absence of being connected to an earth stake, is floating. It is appreciated that in other embodiments housing 19 will be formed of a conductive material other than sheet metal.
  • circuit 1 is contained wholly within housing 19, in this embodiment generator 2 is not. Particularly, housing 19 does not fully encompass the petrol- engine, primarily to allow better management of the heat and gases associated with that engine.
  • housing 19 more fully covers the engine and includes additional ventilation - for example, vents and/or fans — to manage cooling air flows.
  • Motor 10 is disposed within a prismatic steel motor housing 20 that is spaced apart from housing 19. Housing 20, like housing 19, is electrically isolated from all the terminals and, in the absence of being connected to an earth stake, is floating. It is appreciated that in other embodiments housing 20 will be formed of a conductive material other than steel.
  • motor 10 and housing 20 are not physically fixed and are portable.
  • motor 10 is used to drive a condenser of a portable refrigerator (not shown) that is also disposed within housing 20. In other embodiments additional or alternative loads are included.
  • motor 10 is contained within a portable electrical tool such as an electric drill, an electric hammer, a nail gun, and other tools.
  • a portable electrical tool such as an electric drill, an electric hammer, a nail gun, and other tools.
  • the load is able to be any electrical load suitable for use with the voltage and current waveforms provided at terminals 7 and 8.
  • Circuit 1, including detector 11 and device 15, is encapsulated in a sealed housing (shown schematically) that is disposed within housing 19.
  • the encapsulation takes the form of a polyurethane material that envelops all the components within the sealed housing.
  • the material includes equal parts CCM-80 Parts A and B 5 with a coloring.
  • This material in the form of a viscous fluid, is poured through a small aperture in the sealed housing to envelope the components and fill any voids between the components and/or the sealed housing.
  • the material is allowed to set to form a barrier that is both water impermeable and electrically insulating. This encapsulation has the added advantage of making circuit 1 more difficult to tamper with or damage.
  • device 1 is able to be encapsulated due to its inherently low power consumption.
  • alternative encapsulation is used, such as foams.
  • the environmental protection is provided by more direct mechanical arrangements such as a sealed housing that includes interacting O-rings and sealing faces and/or webbing.
  • a sealed housing that includes interacting O-rings and sealing faces and/or webbing.
  • the sealed housing for circuit 1 is a two-piece construction, where the two pieces are injection molded and sealed against each other. In use, the sealed housing has external dimensions of about 65 mm x 45 mm x 45 mm.
  • the sealed housing has external dimensions other than 65 mm x 45 mm x 45 mm.
  • the external dimensions are greater than 65 mm x 45 mm x 45 mm to provide greater heat protection for circuit 1.
  • the sealed housing for circuit 1 is mounted directly to an interior surface of housing 19 adjacent to where terminals 7 and 8 emerge from housing 19.
  • the sealed housing, while being disposed within housing 19, is mounted directly to other than the interior surface of housing 19.
  • the sealed housing is integrally formed with housing 19.
  • the encapsulation is in the form of a heat-shrink material about the encapsulated components.
  • the sealed housing is encapsulated by heat-shrink material.
  • Circuit 1 is effectively passive, in that it consumes little power and dissipates little heat during normal use. During the presence of a fault condition circuit 1 consumes little energy and only operates for a very short time. Accordingly, encapsulation is possible without the danger of thermal runaway. While, in the Figure 1 embodiment, there is not a strong need for encapsulation - as circuit 1 is well shielded from environmental conditions by being disposed within housing 19 — in other embodiments such as marine and aircraft applications the need is greater. [0070] In other embodiments, circuit 1 is disposed in other than housing 19.
  • Input 14 of detector 11 is electrically connected with a conductor 25 that defines a floating earth for generator 2 and motor 10.
  • Conductor 25 is bundled with conductors 17 and 18 within cable 9, with conductor 25 being defined by what is normally the "earth" conductor in a standard three-conductor mains cable. It will be appreciated that as a floating earth, conductor 25 is not, in fact, connected to earth, and should not be confused with the earth that is available in an MEN system. Rather, conductor 25 ties housing 19 and housing 20 to a common floating voltage.
  • additional components are also joined to conductor 25 such as the metal housing of electrical tools, motor stators, and other conductive components that should, in normal operation, be isolated from the active or phase voltage being provided to the load.
  • conductor 25 is connected with. any conductive component that is likely to come into physical contact with an operator or other person and which should, under normal operating conditions, be isolated from the phase voltage. As will be described in more detail below, if the potential of any one or more of these components rises beyond a threshold voltage there arises a fault condition.
  • less than all of the conductive components that should, in normal operation, be isolated from the active or phase voltage are electrically connected to conductor 25.
  • only a single conductive component is electrically connected to conductor 25.
  • only housing 10 is electrically connected to conductor 25 on the basis that should a fault occur this housing poses the greater risk to operator harm.
  • Detector 11 monitors the voltage of conductor 25, and hence the potential of housings 19 and 20 and any other conductive component connected to conductor 25. If this voltage moves outside a predetermined threshold from the voltage of terminal 6 (the neutral terminal) a fault condition is defined, and a fault signal is provided by detector 11 at output 13. The switching device 15 is responsive to that fault signal for isolating motor 10 from generator 2. That is, if the housings - or whatever other components are connected with conductor 25 - rise in potential relative to the neutral conductor so as to create a potentially hazardous situation for operators or other personnel, the supply of electrical power to the relevant load or loads is terminated.
  • terminals 3 and 4 are disposed within housing 19 and are not typically subject to causing faults such as those detected by the present embodiment. It is usual for generator 2 to have additional protection circuitry (not shown) for protecting personnel and the generator from short circuits between terminals 3 and 4 or terminals 7 and 8. Circuit 1 is entirely compatible with the existing protection circuitry used by generator 2, while providing additional protection to personnel.
  • both housing 19 and housing 20 are floating at zero voltage or a very small voltage.
  • the lower threshold for a fault voltage is when conductor 25 is about 3 Volts DC greater than the voltage on the neutral terminal. In other embodiments alternative thresholds are used, although preferably a threshold that is less than the safe touch potential.
  • circuit 1 is able to be used instead of or in addition to existing protection circuitry included with generator 2. Circuit 1 does not interfere with that existing circuitry during normal operation and is entirely compatible with it. This allows circuit 1 to be easily and cost-effectively retrofitted to existing generators and other power supplies. [0076] Moreover, it has been found that the operation of circuit 1 is quicker than conventional solid-state protection circuitry by at least about 10 milliseconds, and more typically by about 15 milliseconds. Accordingly, when fitted with conventional protection circuits it is not unusual for a fault condition to be removed by circuit 1 prior to the existing protection circuits acting.
  • housings 19 or 20 are connected to earth via an earth-stake
  • a relatively high resistance to earth it is possible for a relatively high resistance to earth to exist. That is, while conductor 25 may be notionally "earthed" by connection to an earth-stake, the effectiveness of the earth connection will vary with time due to changes in climatic conditions, soil conditions, and many other factors. Even with such an earth connection it has been found that circuit 1 will continue to operate effectively, whereas the efficacy of the conventional protection circuitry will be more usually compromised. The greater the resistance to earth the more effective the embodiment of the invention becomes, which is typically the converse of what occurs with conventional protection systems.
  • the embodiment illustrated in Figure 1 makes use of 240 Volts AC which, for conventional protection systems, would provide a hazardous situation once the earth resistance exceeded about 1,000 Ohms. At this point the effectiveness of conventional protection systems - such as RCDs - has considerably, if not fully, degraded.
  • a conventional solid state protection circuit would typically take about 30 milliseconds to remove the fault condition.
  • the peak fault current flowing for a 240 Volts mains appliance could easily be in the order of hundreds of amps before the fault condition is removed.
  • the control circuit 1 of Figure 1 is able to remove the same fault in about 15 to 20 milliseconds, with typical fault currents being an order of magnitude less than the conventional systems. More detail on the operation of circuit 1 is provided below in combination with the description of Figure 2.
  • This high speed of operation and relatively low peak fault currents allow circuit 1 to act, in practice, as a quasi-circuit breaker. That is, circuit 1 does not require large fault currents to be flowing to detect a fault condition. Rather, circuit 1 is responsive to a voltage and draws little current, and operates to prevent large fault currents from flowing in the first place.
  • the conventional protection circuits in stark contrast, rely upon the existence of large fault currents to initiate triggering.
  • generator 2 provides a 7.5 kW supply (at 240 Volts AC, 32 Amps, and 50 Hz) at terminals 3 and 4, in other embodiments alternative voltages, currents and frequencies are provided.
  • circuit 1 is included, the same circumstances give rise to a fault condition, as conductor 25 would be at voltage considerably more than 3 Volts DC in excess of the voltage of the neutral conductor. That is, use of protection circuit 1 allows the fault condition to be removed without having to have an operator coming into contact with the fault and being exposed to the risk of electrocution.
  • Circuit 1 includes an input terminal 5 for electrically connecting with terminal 3 of generator 2 that, in use and as described above, provides a 240 Volts AC source voltage.
  • An output terminal 7 is electrically connected with a load in the form of motor 10.
  • a detector that is, detector 11 - has an input 31 that, in use, is connected to terminal 5. The detector is responsive to a reference signal, in the form of the voltage signal on conductor 25, being within a predetermined range for electrically connecting input 31 and output 13 to apply the source voltage to output 13.
  • a switching device that is, device 15 - is electrically connected to the output 13 and is responsive to the source voltage being applied to output 13 for progressing between the first mode and the second mode.
  • Detector 11 includes a detector relay in the form of a low DC voltage relay 33.
  • Relay 33 has a sensor coil 34, a first sensor contact 35 and a second sensor contact 36. Coil 34, when energized by the reference signal on conductor 25, changes the state of relay 33 and connects contact 35 to contact 36.
  • Relay 33 is a low voltage armature relay and, more particularly, a small signal relay. Such a relay is, in some jurisdictions, referred to as a telecom-type relay.
  • the switching voltage of the relay is rated at about 5 Volts DC, but there is often considerable variation between notionally like relays. Due to the nature of the fault voltages being of considerably greater magnitude than the switching voltage of the detector relay, the operation of circuit 1 is not adversely affected by the variations in switching voltages. However, regard is had to, amongst other things, the likely range of those switching voltages for a given relay when designing detector 11.
  • detector 11 includes a current limiting resistor 37 in series with a diode 38 for limiting the current through coil 34 in the event of a fault condition.
  • the resistance of resistor 37 is selected on the basis of the predetermined fault voltage to be detected, the maximum likely fault voltage to be carried by conductor 25, the notional switching voltage of detector relay 33, and the series resistance of coil 34. It will be appreciated by those skilled in the art that the lesser the resistance of resistor 37 the greater the sensitivity of detector 11, in that a smaller potential on conductor 25 will result in coil 34 being energized and, hence, relay 33 changing states.
  • resistor 37 has a resistance of 8.2 kOhms.
  • circuit 1 is the substantively the same, with one exception being resistor 37 has a resistance of 4.7 kOhms. In other embodiments resistor 37 has a resistance of other values.
  • Diode 38 is provided to half- wave rectify any fault voltage on conductor 25 to prevent energizing coil 34 with the wrong polarity. Moreover, in line with the fast acting nature of circuit 1, diode 38 is an IN4007 diode, which is a fast acting diode having a minimum rating of 1,000 Volts at 1.5 Amps. Another suitable diode is an IN5408 diode, which is rated at 1,000 Volts at 3 Amps. On the basis of the teaching herein it would be appreciated by those skilled in the art that other diodes would be suitable.
  • the switching voltage is that voltage at which the detector relay will change state: that is, the voltage at which the relay will switch from one state to another in response to a fault condition. Due to the inherent hysteresis characteristics of the relay is not unusual for any given relay to have a switching voltage that is different when progressing from one of the states to the other than vice versa. In the present embodiments the important consideration is the switching voltage to progress the relay from the non-energized state to the energized state. The switching voltage at which the relay progresses from the energized state to the non-energized state is not critical. [0090] The detector relay is left in a non-energized state during normal operation, in that coil 34 is not drawing any current.
  • Device 15 includes a mains voltage switching relay 41 having: a switching coil 42 that is electrically connected to output 13; and a first switching contact 43 and a second switching contact 44.
  • Coil 42 is not energized and, hence, relay 41 is in a first mode such that contact 43 is electrically connected with both terminal 5 and terminal 7, while contact 44 is electrically connected with both terminal 6 and terminal 8. In other words, in this mode the load is able to be powered by the generator.
  • coil 42 When a fault signal appears on output 13, coil 42 is energized as the full voltage at terminal 5 is applied across coil 42. That is, one end of coil 42 is connected to output 13, which is now connected to terminal 5, and the other end of coil 42 remains connected to terminal 6. That being so, relay 41 progresses from the first mode to the second mode to change the electrical connection of contacts 43 and 44. Particularly, contact 44 is isolated from output 13 such that coil 34 is isolated from terminal 6. In response, coil 34 is allowed to de-energize.
  • contact 43 is electrically isolated from terminal 7, and electrically connected to maintain the full voltage at terminal 5 across coil 42. In that way, once a fault condition is detected, not only does circuit 1 act quickly to electrically isolate terminals 7 and 8 from live terminals 5 and 6, but relay 41 latches in the second mode as the voltage at terminal 5 is applied to coil 42.
  • Relays 33 and 41 are sequentially connected to provide a cascading effect.
  • cascaded relays which both include de-energized coils during normal operating conditions — is described in the earlier pending Patent Cooperation Treaty Patent Application No. PCT/AU03/0O983, the disclosure of which is incorporated herein by way of cross-reference.
  • the Figure 2 embodiment includes, in addition, a direct connection between terminal 5 and input 35. This results in circuit 1 being faster acting than the earlier devices as the full voltage at terminal 5 is more quickly applied to energize coil 42 of relay 41. Having input 35 directly connected to terminal 5 also reduces the risk of relay 41 not latching in the presence of a fault condition.
  • the average response times for circuit 1 are 15 milliseconds, with 18 to 20 milliamps of earth leakage current flowing. This is on the basis of 240 Volts AC supply, and relay 33 having a notional 5 Volt DC switching voltage and a 20 Ohm coil resistance. It will be appreciated that only about 5 milliamps will be required through the coil of detector relay 33 to result in that relay changing states. This results in low energy dissipation within the sensor relay during a fault condition. That is, there is very little current required to detect the fault condition, and that current will only flow for about 15 milliseconds, after which coil 34 will be isolated from the fault due to the operation of relay 41.
  • circuit 1 This operation of circuit 1 is to protect relay 33 from the voltages on conductor 25 which can equal or, in the case of a voltage spike, exceed the mains phase voltage provided at terminal 5. Testing has shown that even when the mains voltage is applied to conductor 25 to simulate a fault condition, relay 33 is capable of over 500,000 operations as it is only exposed to the higher voltages for a very short time for each fault condition. Accordingly, it is possible to gain the sensitivity of a low DC voltage relay to detect a fault condition. [0095]
  • the response time is the time period between the fault occurring and the power being disconnected from the load. It will be appreciated for similar conditions a solid state RCD will typically trigger in about 30 milliseconds, although this varies considerably between devices. Typical RCD fault currents for triggering are 30 milliamps ⁇ 10%.
  • both relay 33 and 41 are passive during normal operation, and only consume power when working to isolate the load. Moreover, relay 33 will only draw a very small current for a short time during a fault condition. Relay 41, however, may remain active for a number of minutes, hours, days or indefinitely depending upon the circumstances.
  • Relay 33 is relatively small physically and electrically - certainly in comparison to relay 41 — and is not designed for use with relatively high voltage such as mains voltages. Notwithstanding, relay 33 and like relays are able to be applied to the present embodiment due to operation of circuit 1 to protect the detector relay once its role in detecting a fault has been performed. Particularly, the cascaded nature of the relays allows relay 41 to gain the benefit of the fast detection and switching of relay 33, and for relay 33 to be quickly thereafter relieved of the electrical stresses of the mains voltages by the operation of relay 41. [0098] As presently understood, the increase speed of progression of circuit 1 between the first mode and the second mode is a result of:
  • Detector 11 also includes a neon lamp 81 across coil 34 for providing additional high voltage protection for that coil. Should the voltage across coil 34 exceed about 90 Volts, the gas within lamp 81 energizes and creates a low impedance conductive path. This provides a failsafe mechanism to divert excessive current that could otherwise damage coil 34 and which is not required to energize the coil. In other embodiments where a shorter operational lifetime for relay 34 is tolerable, or cost is a particularly significant factor, lamp 81 is omitted.
  • Lamp 81 in this embodiment, is a standard helium neon gas lamp having a 90 Volt flashover. In other embodiments alternative lamps or high-voltage protection devices are used. In an alternative embodiment, use is made of a current shunt in parallel with coil 34 to limit the current in that coil.
  • a resistor 82 and a diode 83 are included within detector 11. These are equivalents to resistor 37 and diode 38 respectively, and are selectively electrically connected in series between coil 34 and terminal 7 to allow testing of the operation of circuit 1.
  • the testing involves an operator manually depressing a normally open switch 84 to apply the active phase - that is, the voltage at terminal 7 - to coil 34 via resistor 82 and diode 83. It will be appreciated that this creates a condition that coil 34 finds an equivalent to a fault condition and, hence, relay 33 operates to provide a fault signal at output 13. In turn, relay 41 will change state to isolate terminal 7 from terminal 5. Accordingly, coil 34 will no longer be subject to the voltage at terminal 5.
  • Device 15 includes a mains rated capacitor 85 in parallel with coil 42.
  • the primary role of capacitor 85 is to minimize the risk of "drop out" of relay 41. That is, once terminal 5 is connected to output 13 by relay 33, there is a risk that in the short time it takes relay 41 to electrically connect terminal 5 with the active side of coil 42 — through the changing in state of contact 43 - that coil 42 will not have been maintained sufficiently energized due to coil 13 being isolated — by the change in state of contact 44.
  • capacitor 85 is a 0.22 ⁇ F mains voltage polyester capacitor.
  • Circuit 1 also includes a varistor 86 between terminals 5 and 6 to provide additional over- voltage protection for motor 10. It will be appreciated by those skilled in the art that such protection is often provided by a generator, and is not required when circuit 1 is retrofitted to that generator.
  • a varistor is a variable resistor typically including solid state technology. In the present embodiment use is made of a symmetrical varistor.
  • Circuit 1 also includes a normally closed switch 87 that is disposed between one end of coil 42 and terminal 6. This switch is in the current return path to the neutral phase and typically remains closed to allow normal operation of circuit 1.
  • a normally closed switch 87 that is disposed between one end of coil 42 and terminal 6. This switch is in the current return path to the neutral phase and typically remains closed to allow normal operation of circuit 1.
  • circuit 1 is included within a sealed housing. In addition, all of the electronic components of circuit 1 are mounted on a single double- sided circuit board having dimensions of about 60 mm x 40 mm.
  • the circuit board is of standard non-flammable UL/EC approved fiberglass construction, and includes tracks that accommodate the relevant current flows. It will be appreciated that switches 84 and 87 include respective manually operable buttons that extend from the housing. It is appreciated that in other embodiments circuit boards other than 60 mm x 40 mm will be used. [0106] Reference is now made to Figure 3 where there is illustrated a further embodiment of the invention in which a control circuit 51 is applied to a portable inverter 52, and where corresponding features from other figures are denoted with corresponding reference numerals.
  • Circuit 51 is illustrated with two input terminals 3 and 4, and two output terminals 7 and 8. Similarly to the Figure 1 embodiment, terminal 3 and terminal 7 are, in normal use, electrically connected with the active phase provided by inverter 52. Also, terminals 4 and 8 are, in normal use, electrically connected to the neutral terminal of inverter 52. In other embodiments, the inverter includes more than one phase terminal, and circuit 51 includes a corresponding number of outputs. [0108] Circuit 51 and inverter 52 are collectively mounted internally of housing 19, which in turn is located on a vehicle 53.
  • the vehicle includes a 12 Volt DC automotive supply 54, which supplies power to the electrical systems (not shown) of vehicle 53, and to inverter 52 to allow the generation of a 240 Volt AC supply at terminals 3 and 4.
  • inverter 52 while being mounted to vehicle 53, is supplied power from a source other than supply 54.
  • inverter 52 is supplied power by an internal combustion engine/generator that is also mounted to the vehicle, and which is able to operate independently of the supply 54.
  • Vehicle 53 includes a generally conductive chassis 55, and the supply 54 includes a so-called negative earth, where the earth connection is referenced to chassis 55 by way of an earth strap 56. It will be appreciated that earth strap 56 is connected to chassis 55 at only one point.
  • chassis 55 is generally conductive, it is possible to have quite some resistance between the different points on the chassis. However, neither this factor, nor the absence of an earth-stake, hinders the operation of this embodiment of the invention. These same factors, however, pose significant problems to most prior art protection systems.
  • chassis 55 is formed of metal such as steel.
  • chassis 55 is formed of a conductive material other than steel.
  • Terminals 7 and 8 extend from housing 19 to define, together with conductor 25, a three-pin electrical mains outlet 90 that is schematically represented. Cable 9 defines at one end a complementary electrical plug that is selectively engaged with outlet 90 to allow the supply voltage to be provided to an electrical plug 91 of a remotely located tool.
  • a tool in the form of an electric drill 57, having an electric motor 58 is attached to the other end of cable 9.
  • different tools or other electrical appliances are supplied power via circuit 51.
  • electrical load includes a single electrical load or a combination of separate loads that collectively define a single load at a given point in time.
  • inverter 52 is able to supply power via circuit 51 to a single electrical appliance or electrical tool, or to a plurality of such loads, whether that occurs either sequentially or simultaneously.
  • a fault condition at any one of those loads will disconnect power to all the loads.
  • conductor 25 is floating, and is connected to the relevant conductive components that, in use: • Should be either floating or at zero voltage during normal operation.
  • Circuit 51 includes switching device 15, which operates in the same manner as described with reference to the Figure 1 embodiment. In the event of a fault condition - that is, if a voltage on conductor 25 is more than about 3 Volts DC above the neutral terminal 6 - circuit 51 progresses to the second mode to prevent the supply of voltage to the drill.
  • vehicle 53 when stationary, is able to be earthed by an earth-stake (not shown). However, in practice this is not usual, and even if attempts are made to do so, the effectiveness of the earth is often far less than ideal. Regardless of the existence of an earth connection, or the soundness of that connection, circuit 51 continues to operate in the event of a fault condition, thus reducing the risk of injury to personnel that would not have occurred through reliance upon conventional protection circuitry.
  • Input 14 of device 15 is connected to chassis 55 at a convenient location based upon the mounting location of housing 19.
  • vehicle 53 is a light truck having a metal tray 101 mounted to chassis 55 for carrying a physical load. Tray 101 is mounted to chassis 55 by a plurality of spaced apart metal mounting blocks 102 in combination with retaining devices (not shown) such as U-bolts and other fastening means. In other embodiments alternative mounting arrangements are used.
  • Tray 101 extends longitudinally, and at one end 103 includes a metal headboard 104 that extends upwardly from the tray to provide a protective barrier between any physical load carried on tray 101 and a cabin (not shown) of vehicle 53.
  • Housing 19 is fixedly mounted to tray 101 adjacent to headboard 104 and is intended to remain on the tray for an extended period.
  • a first 12 Volt DC insulated cable 105 extends from housing 19 and through headboard 104 to connect inverter 52 to supply 54.
  • a further insulated 12 Volt DC cable 106 which defines part of conductor 25, extends from within housing 19 and through tray 101 to terminate in an end that is secured to a metal plate 107. The plate is bolted directly to chassis 55 to electrically connect conductor with chassis 55 at a connection point 108.
  • Mounted externally to housing 19 are three mains sockets 108 based upon the Australian configuration for receiving respective complementary mains plugs. These sockets are all supplied power by inverter 52 via circuit 51. In other embodiments alternative numbers of sockets 108 are provided.
  • Each socket includes a respective master switch 110 to allow an operator to switch the socket between an active and a non-active configuration. That is, if inverter 52 is operable, each socket 109 will only be able to supply power to the associated load if the respective switch 110 is in the active configuration.
  • the sockets 109 each include three apertures for receiving complementary pins of an electrical plug.
  • the convention used in Australia is for the lowermost aperture to receive the earth pin of the plug.
  • the pin inserted into the lowermost aperture is electrically connected to conductor 25, not to the earth of the MEN system. More particularly, the pin will be electrically connected to chassis 55 via cable 106.
  • circuit 51 still functions to protect any load and personnel from electrocution or electric shock. For there is typically enough resistance to earth to ensure, in the event of a fault, that detector 11 provides a fault signal. As detector 11 only requires about 3 Volts DC to trigger this allows effective operation even for quite low resistance to earth.
  • circuit 1 continues to operate in the embodiment provided in Figure 6. This arises from the more typical arrangement with vehicles for conductor 25 to be connected to chassis 55 at a location somewhat spaced apart from the actual earth point for the supply 54.
  • stake 111 is connected to chassis 55 by an insulated cable 112. This cable is, at one end, electrically connected to stake 111, and at the other end electrically connected to metal plate 113 that is bolted to chassis 55 at location 114. That is, location 114 is spaced apart from location 108. This spacing factor results in some resistance (referred to as the chassis resistance) between conductor 25 and location 114.
  • the chassis resistance is usually sufficient in the event of a fault condition to generate a voltage at input 14 to trigger detector 11.
  • location 114 is intentionally spaced apart from location 108 to ensure that even if the resistance to earth is low, that the chassis resistance is sufficient to allow effective operation of circuit 51. [0124] In the event that earth-stake 111 is not used, and chassis 55 remains floating, the chassis resistance is not relevant and circuit 51 continues to operate to protect drill 20 and any other load.
  • FIG. 4 A further embodiment is illustrated in Figure 4 where corresponding features are denoted by corresponding reference numerals.
  • Inverter 52 is connected similarly to inverter 51 to supply a load (not shown in this embodiment) via a control circuit 121.
  • Circuit 122 is similar to circuit 51 of Figure 3 but includes, in addition, a protection device 122 for more comprehensively isolating terminals 7 and 8 from terminals 5 and 6 when there is no power applied to terminals 5 and 6 by inverter 52.
  • Device 122 interfaces, on the one hand, with inverter 52 via terminals 5 and 6 and, on the other hand, with device 15 via conductors 123 and 124.
  • FIG. 7 where there is illustrated an embodiment of a protection device 122.
  • This device includes a mains-rated armature relay 125 with two contacts 127 and 128 that are normally open (as shown) and a relay coil 129 that is connected between terminals 5 and 6.
  • inverter 52 provides an electrical potential to those terminals, coil 129 will be energized and contacts 127 and 128 will both close. This causes terminal 5 to electrically connect to conductor 123, and terminal 6 to conductor 124.
  • the embodiments are also suitable for hybrid vehicles, although it will be appreciated that these vehicles typically use higher voltages of up to about 48 Volts DC as the source voltage.
  • the embodiments are also well suited to marine applications in general, and in particular to: leisure craft; rescue marine; police other services; and tug boats. This allows the safe use of more common mains electrical equipment in the marine environment rather than having to rely upon custom voltage appliances for the specific vessel (which are typically DC voltage appliances). This is extremely advantageous, for example, for a cruise ship where passengers which to bring and use their own 240 Volt equipment, but in an environment where it is safe to do so.
  • the marine craft is a ship with a steel hull
  • that hull provides a conductive superstructure and, hence, a common earth.
  • that hull will also have a resistance - analogous to the chassis resistance referred to above.
  • control circuits of the preferred embodiments that are responsive to the voltage between the hull, at a given point, and the neutral conductor of an electrical outlet near that point. If the hull voltage is greater than a certain threshold, the outlet will be disabled by the control circuit. This is able to occur in addition to the use of a control circuit for each appliance.
  • control circuit of the embodiments is used to protect the electrical appliance (or other electrical load) per se.
  • the embodiments are also well suited for use in aircraft, where they allow the safe operation of, typically, personal electronic equipment.
  • the embodiments are advantageously used with an inverter or generator that provides an AC (or other voltage) that is not considered to be a safe touch-potential. That is, where the AC voltage is typically greater than about 50 Volts.
  • the embodiments described above facilitate the proliferation of such higher voltage equipment by offering a safer environment in which to operate.
  • a neutral conductor is typically provided in an electrical distribution system (for example a MEN system) to act as a return current path for the one or more active phases in that system.
  • an MEN system the neutral conductor is commonly bonded to earth at multiple points.
  • an inverter and generator the "neutral terminal" is either bonded to a conductive superstructure, or left floating. While conventional protection circuitry can be left wanting in such circumstances, the embodiments described above are operable to protect the load in either case.
  • inverters there are two types of inverters: pure sine wave inverters; and modified sine wave (or stepped) inverters. Pure sine wine inverters are more desirable for generating supply voltages for electronic equipment due to the more consistent and clean voltage supply they provide. Modified sine wave inverters are generally less expensive and feed through more interference patterns on the output voltage. The embodiments described above function with both these types of inverters.

Abstract

L'invention concerne un circuit de commande (1) pour un dispositif générateur prenant la forme d'un générateur monophasé portable à essence HP. Le générateur fournit une tension d'environ 240 volts alternatifs entre une borne de phase (3) et une borne de neutre (4). Le circuit de commande (1) comprend deux bornes d'entrée (5) et (6) destinées à être connectées électriquement à des bornes respectives (3) et (4), et deux bornes de sortie (7) et (8) destinées à être connectées électriquement, par un câble électrique (9), à une charge prenant la forme d'un moteur électrique (10). Un détecteur (11) fournit un signal d'anomalie à sa sortie (13) en réponse à un état anormal à son entrée (14). Un dispositif de commutation (15) réagit au signal d'anomalie présent à la sortie (13) en passant d'un premier mode à un deuxième mode. Dans le premier mode, les bornes (5) et (6) sont respectivement connectées électriquement aux bornes (7) et (8) pour permettre au moteur (10) de recevoir la tension alternative des bornes (3) et (4) par le dispositif de commutation (15). Dans le deuxième mode, les bornes (5) et (6) sont respectivement connectées électriquement aux bornes (7) et (8) pour empêcher les bornes (3) et (4) de fournir la tension alternative au moteur (10) par le dispositif de commutation (15).
PCT/AU2007/001470 2006-10-04 2007-10-04 Circuit de commande WO2008040054A1 (fr)

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AU2006905493A AU2006905493A0 (en) 2006-10-04 A control circuit
AU2006905493 2006-10-04
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AU2006225307A AU2006225307A1 (en) 2006-10-04 2006-10-09 A control circuit

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WO2010018454A2 (fr) * 2008-08-14 2010-02-18 Giovanni Pieri Procédé de prévention des électrocutions par contact avec des appareils et installations électriques, et appareil à cet effet
US20110140516A1 (en) * 2009-12-10 2011-06-16 Continental Automotive Gmbh Device for actuating actuators in a motor vehicle
EP2380254A4 (fr) * 2008-12-19 2018-01-10 iEP2 Research Pty Limited Système de protection pour un système de distribution électrique en régime it comportant un conducteur de référence flottant

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WO1998021811A1 (fr) * 1996-11-15 1998-05-22 Thomson Consumer Electronics, Inc. Circuit de detection d'incident pour alimentation a decoupage
US6023400A (en) * 1996-03-28 2000-02-08 Nevo; Hayim Safety adapter for ungrounded electrical socket
WO2004013943A1 (fr) * 2002-08-02 2004-02-12 Protectelec Pty Ltd Circuit de commande et procede permettant la connexion electrique d'une charge a une source d'energie
US20070127170A1 (en) * 2005-12-02 2007-06-07 Ls Industrial Systems Co., Ltd. Inverter

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US5055703A (en) * 1987-11-09 1991-10-08 Perma Power Electronics, Inc. Load protection circuit
US6023400A (en) * 1996-03-28 2000-02-08 Nevo; Hayim Safety adapter for ungrounded electrical socket
WO1998021811A1 (fr) * 1996-11-15 1998-05-22 Thomson Consumer Electronics, Inc. Circuit de detection d'incident pour alimentation a decoupage
WO2004013943A1 (fr) * 2002-08-02 2004-02-12 Protectelec Pty Ltd Circuit de commande et procede permettant la connexion electrique d'une charge a une source d'energie
US20070127170A1 (en) * 2005-12-02 2007-06-07 Ls Industrial Systems Co., Ltd. Inverter

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010018454A2 (fr) * 2008-08-14 2010-02-18 Giovanni Pieri Procédé de prévention des électrocutions par contact avec des appareils et installations électriques, et appareil à cet effet
WO2010018454A3 (fr) * 2008-08-14 2010-09-02 Giovanni Pieri Procédé de prévention des électrocutions par contact avec des appareils et installations électriques, et appareil à cet effet
EP2380254A4 (fr) * 2008-12-19 2018-01-10 iEP2 Research Pty Limited Système de protection pour un système de distribution électrique en régime it comportant un conducteur de référence flottant
US20110140516A1 (en) * 2009-12-10 2011-06-16 Continental Automotive Gmbh Device for actuating actuators in a motor vehicle
DE102009057709A1 (de) * 2009-12-10 2011-06-16 Continental Automotive Gmbh Vorrichtung zur Ansteuerung von Aktuatoren in einem Kraftfahrzeug
US9401596B2 (en) 2009-12-10 2016-07-26 Continental Automotive Gmbh Device for actuating actuators in a motor vehicle

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