WO2006077279A1 - Contactor detector, contactor detector system and method for identifying a contactor - Google Patents

Contactor detector, contactor detector system and method for identifying a contactor Download PDF

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Publication number
WO2006077279A1
WO2006077279A1 PCT/FI2006/000018 FI2006000018W WO2006077279A1 WO 2006077279 A1 WO2006077279 A1 WO 2006077279A1 FI 2006000018 W FI2006000018 W FI 2006000018W WO 2006077279 A1 WO2006077279 A1 WO 2006077279A1
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WO
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Patent type
Prior art keywords
contactor
detector
control unit
monitoring device
characterised
Prior art date
Application number
PCT/FI2006/000018
Other languages
French (fr)
Inventor
Olli Ruonti
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Suomen Pcs Oy
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H47/00Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current
    • H01H47/002Monitoring or fail-safe circuits
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2300/00Orthogonal indexing scheme relating to electric switches, relays, selectors or emergency protective devices covered by H01H
    • H01H2300/03Application domotique, e.g. for house automation, bus connected switches, sensors, loads or intelligent wiring
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B90/00Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02B90/20Systems integrating technologies related to power network operation and communication or information technologies mediating in the improvement of the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as enabling technology in buildings sector
    • Y02B90/22Systems characterised by the monitored, controlled or operated end-user elements or equipments
    • Y02B90/224Systems characterised by the monitored, controlled or operated end-user elements or equipments the elements or equipments being or involving protection elements, switches, relays or circuit breakers
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04SSYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S20/00Systems supporting the management or operation of end-user stationary applications, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
    • Y04S20/10System characterised by the monitored, controlled or operated end-user elements or equipments
    • Y04S20/14The elements or equipments being or involving protection elements, switches, relays or circuit breakers

Abstract

The invention relates to a contactor detector (100), which can be arranged into a functional relationship with a contactor, which contactor detector comprises detecting means for detecting the failed contactor. The contactor detector (100) further comprises a programmable control unit (101), which can be arranged to generate and send an identification code, with which the defective contactor can be identified. The invention further relates to a contactor detector system, which further comprises a monitoring device (200), which has been arranged into a functional relationship with the contactor detector (100), and a method for identifying the contactor. In the method the variable describing the contactor state for detecting the failure of the contactor is measured by the detecting means of the contactor detector, and an identification code is generated and sent to a monitoring device by a programmable control unit (101) of the contactor detector (100) for identifying the failed contactor.

Description

CONTACTOR DETECTOR, CONTACTOR DETECTOR SYSTEM AND METHOD FOR IDENTIFYING A CONTACTOR

TECHNICAL FIELD OF THE INVENTION

The object of the invention is contactor detector, contactor detector system and method for identifying a contactor according to the preambles of the independent claims presented below. The object of the invention is further contactor unit and monitoring unit according to the presentation in the preambles of the independent claims.

BACKGROUND OF THE INVENTION

Conventionally contactors are used for separating and combining an electrical power network and a load coupled thereto. The contactors fail at times, in which case also the devices operated by the contactors are subjected to failure. The failure of a contactor appears, among other things, in malfunctions, which may increase upon its number of functions approaching the typical number of service life functions calculated for a contactor and sometimes prematurely, for example, as a result of contactor overload or overheating. Consequently, in connection with the maintenance operation failures of the production lines are repeatedly detected, which failures are specifically caused by the contactors used in them.

A malfunction of a contactor is possible, for example, when the contactor remains switched on, upon an electric arc produced by a closing spark melting the contactor contacts together. In this case, the consequence can be a failure of a production apparatus or a decrease in the production yield, or even a fire, if the overheating is not detected in time. In practice, it has been found that, for example, the overheat protectors are inefficient to prevent the failure of a device or line controlled by a contactor, to which line the device controlled by the contactor has been installated, because they are typically based on controlling the contactor coil voltage off.

SUBSTITUTE SHEET In known contactor monitoring devices the contactor state is monitored in case of failures. In this case, a variable to be fed to the contactor, such as operating voltage, or a variable going out from the contactor, such as output voltage, is measured with monitoring devices, in which case the failure of a contactor can be detected by concluding it from the measured variables. Upon detecting a failure the monitoring device switches off the voltage to be fed to the connector, for example, with the aid of a contactor relay, in which case damages can be prevented.

The problem of the known contactor monitoring devices is the fact that an individual failed contactor is difficult to detect so that the contactor could be distinguished from other failed or unfailed contactors. For example, if there are several failed contactors, already localization of one failed contactor from several contactors is typically time-consuming. Also, no sufficient information is typically received from different kinds of failures of contactors. The non-operation of a contactor remains often as the only information. Such situation is not desirable from the point of view of the maintenance operation.

OBJECTS OF THE INVENTION

The object of the present invention is to reduce or even totally eliminate the above- mentioned problems, which appear in the prior art.

The object of the present invention is to provide a contactor detector and a contactor detector system as well as a method for identifying a contactor.

The above-mentioned disadvantages are eliminated or reduced with the present invention, which is characterized in what is defined in the characterising parts of the independent claims presented further below.

Some preferred embodiments according to the invention are disclosed in the dependent claims presented further below. SUMMARY OF THE INVENTION

A typical contactor detector according to the invention can be arranged into a functional relationship with a contactor, and the contactor detector comprises detecting means for detecting a failure of a contactor. The contactor detector according to the invention further comprises a programmable control unit, which can be arranged to generate and send an identification code, with which the failed contactor can be identified.

A typical contactor detector system according to the invention comprises at least one contactor detector, which can be arranged into a functional relationship with a contactor, which contactor detector comprises detecting means for detecting a failure of a contactor. The contactor detector system according to the invention further comprises a monitoring device, which has been arranged into a functional relationship with a contactor detector, and a programmable control unit, which can be arranged to generate and send an identification code to said monitoring device for identifying the failed contactor.

In a typical method according to the invention for identifying a contactor by the detecting means of the contactor detector a variable describing the contactor state is measured for detecting a failure of a contactor, and an identification code is generated and sent by a programmable control unit of the contactor detector to a monitoring device for identifying the failed contactor.

A typical contactor unit according to the invention comprises at least one contactor and at least one contactor detector, which has been arranged into a functional relationship with a contactor, which contactor detector comprises detecting means for detecting a failure of a contactor. The contactor unit according to the invention further comprises a programmable control unit, which has been arranged to generate and send an identification code, with which the failed contactor can be identified. A typical monitoring unit according to the invention comprises at least one contactor and at least one contactor detector, which has been arranged into a functional relationship with a contactor, which contactor detector comprises detecting means for detecting a failure of a contactor. The monitoring unit according to the invention further comprises at least one monitoring device, which has been arranged into a functional relationship with a contactor detector. The contactor detector according to the invention further comprises a programmable control unit, which has been arranged to generate and send an identification code to said monitoring device for identifying the failed contactor.

In this context the contactor refers, for example, to a device, which comprises an electromagnetic coil, connectors in the ends of the coil, from which electric current can be supplied to the coil, and furthermore, a contact circuit arranged to be opened and closed, with which contact circuit the supplying electrical power network can be separated from the load and connected to the load, and which contact circuit is controlled by said electromagnetic coil. The contactor refers herein also to a so called semiconductor contactor, which is an entity formed by one or more semiconductor switches and a control unit constructed together with this/them, and with which semiconductor contactor a high current load is controlled with a low and/or little power consuming AC- or DC-voltage.

It has now been found that a failed contactor or a contactor that will soon fail can be readily and simply detected and identified from other contactors with the aid of a contactor detector, when a programmable control unit, which is arranged to send an identification code specific to the contactor in question, is arranged to the contactor detector. Thus, to an individual contactor or contactor group an identification code of their own can be arranged, on the basis of which identification code the contactor or contactor group can be identified upon its failing or when otherwise needed.

The function of a contactor can be represented, for example, in the following table, in which its different alternative functional states have been described. The following states, for example, describe the function of a contactor: electric current is fed through the coil the output voltage of a contactor is unequal to zero no electric current is fed to the coil the output voltage of a contactor is equal to zero electric current is fed through the coil the output voltage of a contactor is equal to zero no electric current is fed to the coil the output voltage of a contactor is unequal to zero

The first two lines of these functional states describe functional states, when a contactor functions in a normal way. The following two lines describe functional states, when a contactor functions abnormally, i.e. is failed. In addition to these functional states the response times elapsing for the opening and closing of the contacts of the contact circuit of a contactor can be measured with the contactor detector described in the invention. The failure of a contactor can be concluded, for example, from its functional states and/or from the change of its response times, whereupon an identification code can be formed on the basis of them. For example, when no electric current is fed to the coil, the contacts of a contactor should be open. If the output voltage of a contactor is then unequal to zero, it can be concluded from the functional state that the contactor contacts have melted together. Sometimes the contactor can operate normally, i.e. no discrepancies can be perceived in its functional states, but changes can occur in its response times, from which changes possible coming problems can be concluded. For example, the increase of the response times can anticipate the coming failure of a contactor.

The contactor detector comprises a programmable control unit, which can be arranged to generate and send an identification code for identifying a failed contactor and to receive an identification call sent by a monitoring device, by responding to which identification call the function of the contactor detector is ensured. When there are several contactor detectors, a specific identification code can be formed to each contactor detector, with which identification code it can be distinguished from the others. The identification code can be determined for control units, either so that already upon manufacturing each control unit is given an individualized identification code of its own, i.e. its "address", or so that individual identification codes of the control units are programmed to each control unit at their installation stage. In the latter case, when an individual control unit fails, it is easy to replace it with a corresponding control unit, to which it is programmed the same identification code than the failed control unit to be replaced had. In this case, no other changes need to be made to the monitoring system. When necessary, with the control unit the failure type of a failed contactor can be identified so that the information concerning failure type of a contactor is included in said identification code. The contactor failures, for example, the melting together of contactor contacts, the non-operation of a contactor and the changing of response times elapsing for the opening and closing of the contacts from the possible set values, can be identified and thus distinguished from each other on the basis of an identification code. Also the failure of the control unit of a contactor so that it keeps the contactor continuously switched on can be detected with the contactor detector system.

An identification code can be formed by switching a load on and off to operating voltage produced by the control unit to create pulses so that the contactor detector can be identified on the basis of an identification code. Operating voltage is loaded in pulses on the basis of the information transmitted by the detecting means, for example, the coil voltage of a contactor, the output voltage of a contactor, the response times elapsing for the opening and closing of a contactor and/or the number of the closings of a contactor. In this case, the control unit receives information from the detecting means concerning, for example, the indicated voltage values for forming the identification code. The values of the coil voltage and the output voltage can be compared with the known control values of the voltages and response times in the memory of the control unit. These control values can be programmed to the control unit beforehand or from the user interface unit of the monitoring device. When a failure is detected in a contactor on the basis of the comparations, the control unit generates an identification code, on the basis of which the failed contactor can be detected and identified from other contactors. The identification code can also contain information on the measured values for coil and output voltages of a contactor and the response times. Determination of the pulse ratio and the frequency of the identification code can be programmably realised in the control unit.

The identification code can thus also be formed on the basis of the number of the closings of a contactor. Typically, a predetermined service life, i.e. how many contacts a specific contactor can perform in a specific environment without failing, has been indicated for each contactor. In an embodiment of the invention the number of the openings and the closings of a contactor is calculated with the aid of the control unit of the contactor detector. The calculation of the openings or the closings of a contactor has thus been arranged in connection with the contactor, with which calculation the number of the contacts made by the contactor can be monitored. The number of the openings and the closings of the contactor calculated is then compared to the preset threshold value, upon exceeding of which an alarm is transmitted to the user interface unit of the monitoring device. In this way, a warning identification code can be formed, when the number of the contacts begins approaching the estimated service life of the contactor, for example, the number of the contacts exceeding 80% or 90% of the estimated number of the contacts. This enables the identification and replacing of a contactor that will soon fail before its failure and possible malfunction.

The control unit can be arranged to perform tasks programmed to it, for example, performing an A/D- and/or D/A-conversion, handling of the response times elapsing for opening and closing of the contactor contacts, saving the number of the closings of a contactor, handling of coil and output voltage information and forming of an identification code. Set values needed for performing the tasks, for example, values for the coil and/or output voltage and the response times elapsing for opening and closing of the contacts of the contact circuit of a contactor, can also be programmed to the control unit and saved into the memory. The identification code to be produced in the control unit, can be formed with a signal, which preferably consists of pulse shaped electric current, for example, square pulses. To this signal can be programmably defined, for example, the amplitude, pulse width, cycle time and frequency of a signal, which can be specific for each contactor detector and can thus be distinguished from each other. The frequency of the identification code can be about 1 kHz or 1-2 kHz. According to an embodiment of the invention the monitoring device can be programmed to priorize the identification codes received from several contactor detectors on the basis of their frequency. Upon sending the identification code from the control unit of the contactor detector to the control unit of the monitoring device the contactor, which is in contact with the contactor detector, can be identified, for example, on the basis of the contents of the identification code.

According to an embodiment of the invention the control unit comprises a microcontroller. The microcontroller can then comprise a processor (CPU), timer circuit, A/D-converter, memory units and input and output units (I/O). Commercially available programming devices can be used for programming the microcontroller. The programming devices typically comprise a programming software, which works, for example, in the computer environment. The computer, for example, a personal computer, can be connected, for example, via its COM-port with the RS- 232-bus to the microcontroller to be programmed. Through the bus program information can be transmitted to both directions. The programming language can be, for example, an assembly language. The clock signals of the control unit can be realised, for example, by a crystal oscillator, with which is produced, for example, a 10 or 20 MHz clock signal. The advantage of the microcontroller is its modifiability. The functions of such control unit can be programmably modified without needing to replace or add other components. Because the functions of the control unit are performed programmably, the number of components of the contactor detector can thus be kept rather low. Such digitally realised solution enables the small size of the contactor detector, in which case it can be readily mounted between the contactors and the terminal blocks. Small size also enables easy retrofit to already existing systems, which are already installed at the electrical cabinets.

The contactor detector according to the invention comprises detecting means for measuring a variable describing the contactor state. With the detecting means, for example, contactor's output and/or input voltage, current, time, frequency, phase, cycle time, amplitude, pulse width, pulse ratio, rise time and/or fall time of the signal, can be measured.

According to an embodiment of the invention the detecting means comprise first detecting means for detecting the output voltage of a contactor. The first detecting means comprise, for example, a resistance coupled to the first phase of the electrical power network, a first diode, which is connected in series with it, a second diode, which is connected in series with it, and after these a second resistance coupled in its one end to the cathode of the second diode and in its second end to the neutral wire of the electrical power network. The first detecting means can further comprise a third resistance coupled to the second phase of the electrical power network and a third diode, which is connected in series with it, the cathode of which diode is coupled to the connection point of the first diode and the second diode. The first detecting means can further comprise a fourth resistance coupled to the third phase of the electrical power network and a fourth diode, which is connected in series with it, the cathode of which diode is coupled to the connection point of the first diode and the second diode. The contactor detector can thus be coupled to a 1-, 2-, or 3-phase electrical power network.

According to another embodiment of the invention the detecting means of the contactor detector comprise second detecting means for detecting the coil voltage of a contactor, i.e. the voltage between the coil connectors. These detecting means comprise, for example, a first resistance coupled to the first connector of the coil, a diode, which is connected in series with the first resistance, a second diode, which is connected parallel with the first diode, and after these a second resistance coupled in its one end to the cathode of the second diode and in its other end to the second connector of the coil. When electric current is conducted to the contactor coil through its connectors, voltage is formed over the coil. When this coil voltage is coupled over the input terminals of the second detecting means, the coil voltage is rectified on the first and second diode, in which case the contactor detector can be used in connection with contactors operating with both AC and DC coil voltages. The current can be limited with said resistances. According to an embodiment of the invention the detecting means have been isolated from the control unit at least by one optocoupler or transformer. The control unit of the contactor detector can thus be isolated from the first detecting means by a first optocoupler and respectively the second detecting means can, when necessary, be isolated from the control unit by a second optocoupler. The input terminals of the first optocoupler can thus be coupled over the ends of the above-mentioned second resistance of the first detecting means. The output of the first optocoupler is then in a functional relationship with the first input of the control unit. Respectively, the input terminals of the second optocoupler can be coupled over the ends of the second resistance of the second detecting means, in which case the output of the second optocoupler is in a functional relationship with the second input of the control unit.

By optocouplers it is possible to arrange a so-called galvanic isolation between the detecting means and the control unit, in which case the galvanically isolated units have no common reference potential, for example, no common ground. As a decoupler may as well be used a transformer, in which case the electric current is transmitted between the primary and secondary windings of the transformer by aid of induction, but the conductors coupled to the coils of the transformer have no galvanic connection to each other.

The value of a variable describing the contactor state indicated by the detecting means, such as the value of the coil and/or output voltage, is typically analog, so it usually has to be digitized, so that it could be handled as digital in the control unit. This can be done before the control unit, preferably by a microcontroller. The digitizing of the voltage values can then be realised by entering the analog voltage values to the control unit through a separate A/D-converter. Typically, there are no memory units in the detecting means, so they cannot store information. The control unit then sends information to its memory units as the A/D-converter digitizes it. The sampling frequency can be, for example, 10 or 20 MHz. The A/D- converter to be used can be, for example, 8-, 10-, 12-, 14- or 16 bit, in which case information is transmitted from a converter to the control unit along a bus of a corresponding capacity. The values of a variable describing the contactor state obtained by the detecting means can be converted into a digital form also by amplifying the obtained analog signal sufficiently by an optocoupler. Then, for example, the signal values exceeding the specific determined frequency are converted into a digital value 1 , and the signal values being below this determined frequency are converted into a digital value 0.

In an embodiment of the invention an inner A/D-converter of the control unit, for example, a microcontroller, can be used for digitizing the coil and output voltages measured by the detecting means. The values indicated for the output voltage are then transmitted from the first detecting means through the first optocoupler to the first transistor stage, and the indicated values for the coil voltage are then transmitted from the second detecting means through the second optocoupler to the second transistor stage. Both of these transistor stages comprise, for example, a transistor and a direct voltage source connected to its collector through a resistance. Then, the operating voltage, for example, of +5 VDC is supplied from the direct voltage source to the transistor. A transistor base of the first transistor stage has been coupled to an emitter of the transistor of the first optocoupler. The transistor base of the second transistor stage has been coupled to an emitter of the transistor of the second optocoupler. In the first transistor stage the collector of the transistor has additionally been coupled to the first input of the control unit and in the second transistor stage the collector of the transistor has been respectively coupled to the second input of the control unit. The emitters of the transistors have been further coupled to the ground. Further, the collectors of transistors of the first and second optocoupler have been coupled to a direct voltage source, for example, of +5 VDC.

When the first optocoupler becomes conductive under the influence of the contactor output voltage supplied to its input terminals, in which case the collector- emitter junction of the transistor of the first optocoupler becomes conductive, voltage is supplied from the direct voltage source through said collector-emitter to the transistor base of the first transistor stage, in which case also its collector- emitter junction becomes conductive. Then, the signal, which is to be conducted to the input of the microcontroller is substantially in the ground potential of the transistor. In this case, the phase of the supplying electrical power network is switched on and it can be observed with the control unit.

When the collector-emitter junction of the transistor of the first optocoupler is not conductive, the collector-emitter junction of the transistor of the first transistor stage is not conductive. Then, the signal, which is to be conducted to the microcontroller to the input is substantially in the potential of the operating voltage. In this case, the phase of the supplying electrical power network is not switched on and thus also this can be observed with the control unit.

Respectively, when the second optocoupler becomes conductive under the influence of the contactor coil voltage coupled over its input terminals, in which case the collector-emitter junction of the transistor of the second optocoupler becomes conductive, voltage is supplied from the direct voltage source through said collector-emitter to the transistor base of the second transistor stage, in which case also its collector-emitter junction becomes conductive. Then, the signal coming to the microcontroller to the second input is substantially in the ground potential of the transistor. The voltage is coupled over the contactor coil and this can be observed with the control unit.

When the collector-emitter junction of the transistor of the second optocoupler is not conductive, the collector-emitter junction of the transistor of the second transistor stage is not conductive. Then, the signal coming to the microcontroller to the second input is substantially in the potential of the operating voltage, for example, of +5 VDC. In this case, no voltage has been coupled over the contactor coil and thus also this can be observed with the control unit.

According to an embodiment of the invention the contactor detector also comprises a signalling and power supply unit, the purpose of which is to receive and transmit further an identification code generated by the contactor detector, to supply operational energy to the control unit of the contactor detector and to possibly receive an identification call sent by the monitoring device, by responding to which call the functionality of the contactor detector is ensured. The signalling and power supply unit can be connected to the control unit of the contactor detector. The control unit of the contactor detector can be arranged to send an identification code to the signalling and power supply unit, which, on the basis of the identification code received from the control unit, loads the operational voltage taken by the signalling and power supply unit for providing the pulse shaped electric current and for sending it further. For example, the transistor of the signalling and power supply unit is then controlled with the identification code to be alternating conductive and non-conductive, in which case the time, when the transistor is conductive and respectively its time, when it is non-conductive, are determined by the identification code, its pulse ratio. For example, at a 50 % pulse ratio, the transistor conducts half of the cycle time of the identification code and stays non-conducting the other half of the cycle time. This pulse ratio can be programmably modified, when needed, by the control unit of the contactor detector so that a numerous group of different identification codes are provided, which are specific to each contactor detector.

The operating voltage taken by the signalling and power supply unit is, for example, +12 VDC, which it receives, for example, from an external voltage source. This voltage is converted in said unit, for example, by a linear regulator or direct voltage source to the operating voltage of the control unit, for example to

+3 - 5 VDC, and supplied to the control unit. According to an embodiment of the invention the contactor detector can comprise a signalling and power supply unit, which comprises a full bridge rectifier, a diode coupled to the output of the full bridge rectifier and further a direct voltage source connected in series with the diode, with which direct voltage source the operating voltage can be supplied to the control unit. Furthermore, the signalling and power supply unit can comprise a transistor stage coupled to the output of said full bridge rectifier and in parallel to said diode for sending further said identification code in case of failure of a contactor. The collector of the transistor of the transistor stage has been coupled through the resistance connected to the collector to the output of the above- mentioned full bridge rectifier, and the transistor base has been further coupled through series resistance to the output of the control unit.

In the contactor detector system according to the invention the contactor detector has been arranged into a functional relationship with the monitoring device. According to an embodiment of the invention the monitoring device comprises a programmable control unit, which can be arranged to receive and detect the identification code sent by the control unit of the contactor detector, with which identification code the failed contactor can be identified. This control unit can be similar to the control unit of the contactor detector, for example, a microcontroller. The power need of the control unit of the monitoring device can be obtained, for example, from a power supply and filtering unit, which receives its operating voltage from an external supply, the voltage of which is, for example, +24 VDC. The voltage taken by this power supply and filtering unit is filtered, for example, by a choke and a LC filter, and transmitted after that, for example, to a switched- mode voltage supply. The switched-mode voltage supply converts the operating voltage, for example, to +12 VDC, and feeds it on to the control unit of the monitoring device.

According to an embodiment of the invention the monitoring device comprises a signalling and power supply unit, which comprises an integrating operation amplifier circuit, with which the identification code generated by the contactor detector can be identified and detected. This is obtained by connecting the signalling and power supply unit through a bus connection, for example, a 2-wire cable bus, to a contactor detector. The signalling and power supply unit processes, for example, integrates the identification code received from the contactor detector. By the handling of the identification code the actual identification code can thus be distinguished from the electromagnetic noise pulses possibly induced thereto, which usually have shorter duration, and from the changes caused by environmental factors, which usually have longer duration. For example, the current consumption of the contactor detector changes under the influence of environmental factors, for example, change of temperature. By the handling of the identification code the changes occurring in the identification code can be distinguished, which changes do not describe the functional state and/or response time of a contactor, but which are caused by external interferences.

According to an embodiment of the invention the functional relationship between the contactor detector and the monitoring device of the contactor detector system has been arranged by a bus interface, preferably by a 2-wire cable bus, with which the identification code can be transmitted from the contactor detector to the monitoring device. With a 2-wire cable bus cost advantage can be achieved, because the 2-wire cable bus, being two-wired, has typically low installation costs compared to Profibus or RS485 bus, which are often used in industry, in which buses more wires are used than in the 2-wire cable bus. The bus interface can be created between the signalling and power supply units of the contactor detector and the monitoring device. Through the bus interface the operation voltage can be supplied to the contactor detector.

According to an embodiment of the invention the information is transmitted in the 2-wire cable bus between the monitoring device and the contactor detector so that the information from the contactor detector to the monitoring device is transmitted as a current message by pulse modulating the supply current of the contactor detector and the information from the monitoring device to the contactor detector in transmitted as a voltage message by pulse modulating the operating voltage.

According to an embodiment of the invention the monitoring device comprises a user interface unit, which is in a functional relationship with its control unit and with which the contactor failure according to the identification code and/or the type of failure of a contactor can be expressed. A display, for example a liquid crystal display, and a keyboard, can be included in such user interface unit.

According to an embodiment of the invention the monitoring device comprises an external device unit, which is in a functional relationship with its control unit. The external device unit can be, for example, a transistor circuit with several, for example, seven or eight, inputs and outputs. The external device unit can act, for example, as a driver for the devices connected to the external device unit. For example, different types of detectors and sensors, such as level switches, vibration sensors, thermal guards, electric motors or relays, can be external devices. With the aid of an external device unit also other external devices than contactors can be monitored with the monitoring device and determine other measurable variables, for example, vibration, pressure or temperature.

In the contactor detector system according to an embodiment of the invention a contactor relay, relay or the like, which is controlled by the monitoring device of the contactor detector system has been arranged in series with each of the contactors. A contactor relay is arranged between the supplying electrical power network and the contactor so that the voltage to be fed to a contactor passes through the contactor relay. When a contactor fails, a contactor detector sends an identification code to the monitoring device of the contactor detector system. The monitoring device receives an identification code from the contactor detector, in which case by concluding from the identification code the monitoring device can control the contactor relay off in the case of failure. The voltage source to the contactor is switched off by the contactor relay, in which case the failed contactor can be made currentless by the control independent from the production device.

Several contactor detectors can be arranged into a functional relationship with the monitoring device of the contactor detector system. In the monitoring device there can be, for example, four group outputs, and each contactor detector can be coupled to any of these outputs. In such contactor detector system there can be, for example 30, 40, 50, 60, 70, 80, 90 or 100 contactor detectors.

In a method according to an embodiment of the invention an identification code is sent from the contactor detector to a monitoring device in predetermined time slots. A time slot, after which it resends the identification code to the monitoring device, can be programmed to a contactor detector. When the contactor detector system is switched on, the identification code is repeatedly after the time slot sent to the monitoring device. An individual identification code can also be sent several times sequentially, for example, three times sequentially, in which case it can be assured that at least one of the sent identification codes reaches monitoring device without interference. If several contactor detectors have been connected to the same monitoring device, the time slots can be programmed so that each contactor detector sends its identification code in its turn, in which case the identification code is received at the monitoring device one identification code at a time. For example, the first contactor detector sends an identification code at the time point of 0 seconds, the second contactor detector sends an identification code in 0,1 seconds, the third contactor detector sends an identification code in 0,1 seconds after the previous one and so on. Thus, the contactor detectors of the contactor detector system have a so-called response order.

In a method according to an embodiment of the invention an identification call is sent from the control unit of the monitoring device to the control units of the contactor detectors of the contactor detector system. With the aid of the identification call, among other things, the clocks of the control units of the contactor detectors can be calibrated. Without calibration the clocks of the control units of individual contactor detectors cannot stay synchronized, but move to different times. This is normally caused by environmental factors, for example, by the fact that different contactor detectors are in different temperatures. An identification call can be sent from the monitoring device to the contactor detectors in appropriate predetermined time slots, for example, every 1 , 3, 5 or 10 minutes. The contactor detectors connected to the contactor detector system respond to the identification call by sending their identification codes back to the monitoring device in a specific predetermined response order. In this way, the contactor detectors can be arranged to ensure their working condition. It can be assured that the response order of the contactor detectors stays right by synchronizing the clocks of the control units of the contactor detectors with the aid of an identification call, in which case an individual contactor detector sends its identification code always in the time point determined to it. With the invention a real-time or an almost real-time calibration or testing of the contactor detectors can thus be obtained. It is clear that an individual contactor detector can at any time send an identification code indicating a failure or a change of the response times of a contactor to the monitoring device, although the contactor detector in question would not be in response turn at that moment. According to an embodiment of the invention the monitoring device can send an identification call also to an individual contactor detector to check its function. Then, from the control unit of the monitoring device an identification call is sent to a specific contactor detector, which responds to it by sending its identification code. In this way, the working condition of the contactor detector in question can be assured.

According to an embodiment of the invention the response times elapsing for the opening and closing of the contacts of the contactor contact circuit are measured with the contactor detector. The measurement of the response times can be arranged to the control unit of the monitoring device or of the contactor detector of the contactor detector system. For measuring the response times the control unit sets into the memory a time point t0joFF), at which the voltage over the terminals of the contactor coil has been switched off, and counts from that time point on a time point toFF. which elapses for the opening of all contactor contacts, in which case the output voltage of the opened contactor is zero. Respectively, from a set time point tojoN), at which the voltage over the coil connectors has been switched on, a time toN, is counted, which elapses for the closing of all contactor contacts, in which situation the contactor output voltage corresponds substantially to the voltage supplied from the network. This is obtained by measuring simultaneously the coil as well as the output voltage of a contactor with the aid of the detecting means.

In a method according to an embodiment time limits are programmed to the control unit for the response times t0N, toFF, about the exceeding of which warning information is transmitted to the user interface unit. The warning information is indicated, for example, on the display or with signal lights of the user interface unit, in which signal lights, for example, the switching on of a light of specific colour, for example yellow, means warning. The warning information can be transmitted to the user interface unit with the aid of an identification code. With the warning information the increase in the response times of a contactor, can be indicated, which fact may be predicted to indicate the expiration of the service life of the contactor in question. In a method according to an embodiment a second time limit is programmed to the control unit, about exceeding of which time limit alarm information is transmitted to the user interface unit. The alarm information can also be indicated on the display of the user interface unit, for example with red signal light. With the alarm information it can be indicated, for example, an immediate replacement requirement of an individual contactor. The warning and alarm information can thus be preferably used in determining the replacement requirement of contactors, because the response time t0N, t0FF slows down, for example, upon ageing of the contactor, in the overheating situation of the contactor, or upon the electric arc sparks caused by inductive loads trying to weld the contacts of the contactor contact circuit together in the opening situation.

In an embodiment of the invention the possible time limits or other variables causing an alarm have been programmed to the control unit of the contactor detector. Upon exceeding the alarm value of a variable the contactor detector generates an alarming identification code, which immediately causes an alarm and transmits the information to the user. In this way, additional delays can be avoided in the danger situation.

In a method according to an embodiment of the invention the electric current consumed by the contactor detector is measured by the monitoring device. In the control unit of the monitoring device the changes of the electric consumption, which changes are programmably determined to another control unit on the basis of their frequency, are distinguished on the basis of the measured electric consumption. Thus, the contactors can be individualized on the basis of the changes of the electric current of the contactor detector.

In a method according to an embodiment of the invention an identification code is sent from the contactor detector along a 2-wire cable bus to the monitoring device, from which operation voltage is simultaneously supplied to the contactor detector along the same 2-wire cable bus. In a method according to an embodiment of the invention the normal state of a contactor or the performed alarm can be stated from the user interface unit of the monitoring device of the contactor detector system, or the test state can be chosen from the user interface. In the test state the contactors can be tested in connection of the preventive maintenance without the alarm moving forward. The test state can thus be chosen from the user interface, for example, by switching off the operating voltage from the contactor detectors for a moment. In the method according to an embodiment of the invention the alarms are indicated in different ways depending on the type of the failure of a contactor, in which case the failure can easily be identified. The identification code corresponding to the alarm can be indicated by a device connected to the monitoring device or by a sound and light signal device belonging to it. The sound alarm can be switched off by the acknowledgement button of the user interface unit, but the signal light stays on, until the failure has been corrected. Upon the contactor contacts melting together the failure is indicated as described above, but with the monitoring device it is possible to control the chosen contactors off for decreasing the thermal stress.

In a method according to an embodiment of the invention an identification code is sent from each contactor detector to the monitoring device after the current of the contactor detector system has been switched on. Such self-testing of the system can also be started manually from the monitoring device.

In a method according to an embodiment of the invention information transmitted from the external device unit for monitoring other devices connected to the external device unit is received with the monitoring device of the contactor detector system. This information can be transmitted on to the user interface unit.

BRIEF DESCRIPTION OF THE FIGURES

In the following, the invention will be described in more detail with reference to the appended figures, in which Fig. 1 shows by way of an example a block diagram of the contactor detector according to an embodiment of the invention, and

Fig. 2 shows by way of an example a block diagram of the monitoring device according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE FIGURES

Fig. 1 shows by way of an example a block diagram of the contactor detector according to an embodiment of the invention. The contactor detector 100 is according to the block diagram divided into four functional blocks: control unit 101 , first detecting means 103, second detecting means 102 and signalling and power supply unit 104.

The contactor detector 100 is coupled according to Fig. 1 through the network connectors L1 , L2, L3, N of the first detecting means 103 to the supplying 3-phase electric power network so that to each phase, for example U, V, W, only one network connector has been coupled. A neutral wire is coupled to connector N. The contactor detector is additionally coupled through the coil connectors 107, 108 of the second detecting means 102 to the terminals of the contactor coil. Further, the contactor detector 100 has been coupled through the connectors 105, 106 of the signalling and power supply unit 104 to external devices, for example, to a monitoring device, which is described further below in Fig. 2. The contactor coil and the phases U, V, W of the electric power network have not been described in Fig. 1.

The purpose of the contactor detector 100 is to measure the voltage over the terminals of the contactor coil through the connectors 107, 108 and the output voltage of the contactor through the network connectors L1 , L2, L3, N, the contactor being coupled to the contactor detector 100, and to identify, how many of the phases U, V, W of the supplying electrical power network are then on or off. The purpose of the contactor detector 100 is further to measure the response times toFF and respectively t0N elapsing for the opening and closing of contacts of said contactor. The purpose of the contactor detector 100 is further to generate and send an identification code, with which the failed contactor can be individualized, and to possibly calculate the number of openings/closings of the contactor. The contactor detector has been adjusted to operate with the coil voltages of between 24 — 230 volts operating by the alternating current (AC) and direct current (DC) coupled to the terminals of the contactor coil.

The first detecting means 103 for detecting the output voltage of a contactor have been illustrated in Fig. 1. The first detecting means 103 comprise an output voltage measurement unit. In the output voltage measurement unit the analog output voltage is rectified and guided to the first input of the control unit 101. From the first input of the control unit 101 the analog rectified output voltage is transmitted to the control unit 101, with which the output voltage is converted to a digital value of the output voltage. This value is saved into the memory of the control unit 101.

The second detecting means 102 for detecting the voltage between the connectors of the contactor coil have been illustrated in Fig. 1. The second detecting means 102 comprise a coil voltage measurement unit. In the coil voltage measurement unit the analog coil voltage is rectified and guided to the second input of the control unit 101. From the second input of the control unit 101 the analog rectified coil voltage is transmitted to the control unit 101 , with which the coil voltage is converted into a digital value of the coil voltage. The digital value obtained this way is saved into the memory of the control unit 101.

The control unit 101 illustrated in Fig. 1 receives its operation voltage from the signalling and power supply unit 104 coupled to the control unit 101. This supplies direct voltage, for example of +5 VDC, to the control unit 101 and receives simultaneously an identification code generated and sent by the control unit 101 and sends an identification code on through its bus connectors 105, 106 to external devices, and receives an identification call sent by the monitoring device, by responding to which call the function of the contactor detector is assured. Fig. 2 shows by way of an example a block diagram of the monitoring device according to an embodiment of the invention. The monitoring device 200 is according to the block diagram divided into three functional blocks: second control unit 201 , second signalling and power supply unit 204 and power supply and filtering unit 205. The monitoring device according to Fig. 2 is further connected to the user interface unit 202 and to the external device unit 203.

The control unit 201 of the monitoring device 200 is according to Fig. 2 coupled through the connectors 206, 207 of the power supply and filtering unit 205 to an external power supply. The monitoring device 200 is through the external device unit 203 and its connectors 210 further coupled to other devices, for example, to relays, level switches or overheat protectors. Furthermore, the monitoring device 200 has been coupled to the contactor detector through the bus connectors 208, 209 of the second signalling and power supply unit 204. The external power supply, other devices and the contactor detector have not been illustrated in Fig. 2.

The control unit 201 of the monitoring device 200 receives its operation voltage, for example, of +12 VDC, from the power supply and filtering unit 205 and converts the received operation voltage further, for example, to +5 VDC, and supplies the changed voltage to the user interface unit 202 and to the second signalling and power supply unit 204. The purpose of the monitoring device 200 is to supply operation voltage, for example, of +12 VDC, through its bus connectors 208, 209 to the contactor detector, to receive simultaneously the identification code sent by the contactor detector and send identification calls through the same connectors 208, 209. The purpose of the monitoring device 200 is further to receive commands, for example, stop, start and interrupt commands, supplied from the user interface unit 202. The purpose of the monitoring device 200 is further to send information included in the identification code received from the contactor detector of the second control unit 201 to the user interface unit 202, in which the information can be indicated, for example, graphically on display, and additionally, when needed, for example, by a sound signal or signal lights. The monitoring device 200 can further be arranged to receive information transmitted from the external device unit 203 for monitoring other devices coupled thereto and for transmitting information on to the user interface unit 202.

The power supply and filtering unit 205 illustrated in Fig. 2 receives its operation voltage through its input connectors 206, 207 from an external supply, which supplies, for example, direct voltage of +24 VDC. Interferences and voltage are filtered in this unit 205. After this the operation voltage is converted, for example, by a decreasing switched-mode voltage supply, for example, of +12 VDC, and supplied to the second control unit 201.

It is apparent to the man skilled in the art that the invention is not limited exclusively to the examples described above, but that the invention can vary within the frames of the claims presented below. The dependent claims present some possible embodiments of the invention, and they are not to be considered to restrict the scope of protection of the invention as such.

Claims

1. A contactor detector (100), which can be arranged into a functional relationship with a contactor, which contactor detector comprises detecting means for detecting a failure of a contactor, characterised in that the contactor detector (100) comprises further a programmable control unit (101), which can be arranged to generate and send an identification code, with which the failed contactor can be identified.
2. A contactor detector according to claim 1 , characterised in that the detecting means comprise first detecting means for detecting the output voltage of the contactor.
3. A contactor detector according to claim 1 , characterised in that the detecting means comprise second detecting means for detecting the coil voltage of the contactor.
4. A contactor detector according to claim 1 , characterised in that the detecting means have been isolated from the control unit (101) by at least one optocoupler or transformer.
5. A contactor detector according to claim 1 , characterised in that the control unit (101 ) comprises a microcontroller.
6. A contactor detector system comprising at least one contactor detector (100), which can be arranged into a functional relationship with a contactor, which contactor detector comprises detecting means for detecting a failure of a contactor, characterised in that the contactor detector system further comprises a monitoring device (200), which has been arranged into a functional relationship with the contactor detector (100), and that the contactor detector (100) further comprises a programmable control unit (101), which can be arranged to generate and send an identification code to said monitoring device (200) for identifying the failed contactor.
7. A contactor detector system according to claim 6, characterised in that the monitoring device (200) comprises a programmable control unit (201 ), which can be arranged to receive and identify the identification code sent by the control unit (101) of the contactor detector (100), with which identification code the failed contactor can be identified.
8. A contactor detector system according to claim 6, characterised in that between the contactor detector (100) and the monitoring device (200) has been arranged a bus interface, preferably a 2-wire cable bus, with which the identification code can be transmitted from the contactor detector (100) to the monitoring device (200).
9. A contactor detector system according to claim 6, characterised in that the monitoring device (200) comprises a signalling and power supply unit (204), which comprises an integrating operational amplifier circuit.
10. A method for identifying a contactor, in which method a variable describing the contactor state for detecting the failure of the contactor is measured by the detecting means of the contactor detector, characterised in that an identification code is generated and sent to a monitoring device by a programmable control unit (101 ) of the contactor detector (100) for identifying the failed contactor.
11. A method according to claim 10, characterised in that an identification code is generated and sent by the programmable control unit (101 ) of the contactor detector (100) for identifying the type of the failure of the failed contactor.
12. A method according to claim 10, characterised in that the coil and output voltage of the contactor are simultaneously measured by the detecting means of the contactor detector for measuring the response times elapsing for the opening and closing of the contacts of the contactor.
13. A method according to claim 12, characterised in that for the response times toN, toFF, to the control unit is programmed a first time limit, upon exceeding of which warning information is transmitted to the user interface unit of the monitoring device, and/or the second time limit, upon exceeding of which alarm information is transmitted to the user interface unit of the monitoring device.
14. A method according to claim 10, characterised in that to the control unit of the contactor detector is programmed a time slot, in the intervals of which the contactor detector sends an identification code to a monitoring device.
15. A method according to claim 10, characterised in that the monitoring device sends an identification call to the control unit of the contactor detector, for example for calibrating the clock of the control unit.
16. A method according to claim 15, characterised in that the identification call is sent from the control unit of the monitoring device to at least two contactor detectors, whereby the contactor detectors respond to the identification call by sending their identification codes to the monitoring device in a predetermined response order.
17. A method according to claim 10, characterised in that the number of the openings and closings of the contactor are calculated by the control unit of the contactor detector.
18. A method according to the claim 17, characterised in that the number of the openings and closings of the contactor calculated is compared to the preset threshold value, upon exceeding of which an alarm is transmitted to the user interface unit of the monitoring device.
19. A contactor unit, comprising at least one contactor and at least one contactor detector (100) arranged into a functional relationship with a contactor, which contactor detector comprises detecting means for detecting failure of a contactor, characterised in that the contactor detector further comprises a programmable control unit (101 ), which has been arranged to generate and send an identification code, with which the failed contactor can be identified.
20. A monitoring unit comprising at least one contactor and at least one contactor detector (100) arranged into a functional relationship with a contactor, which contactor detector comprises detecting means for detecting failure of a contactor, characterised in that the monitoring unit further comprises at least one monitoring device (200), which has been arranged into a functional relationship with the contactor detector (100), and that the contactor detector (100) further comprises a programmable control unit (101), which has been arranged to generate and send an identification code to said monitoring device (200) for identifying the failed contactor.
PCT/FI2006/000018 2005-01-18 2006-01-17 Contactor detector, contactor detector system and method for identifying a contactor WO2006077279A1 (en)

Priority Applications (2)

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FI20050054A FI117256B (en) 2005-01-18 2005-01-18 The contactor detector, contactor detector system and method for identifying a contactor
FI20050054 2005-01-18

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US5825643A (en) * 1993-08-25 1998-10-20 Square D Company Programming device for a circuit breaker
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EP0957556A2 (en) * 1998-05-11 1999-11-17 Eaton Corporation Electrical switching device or trip unit acquiring predetermined settings from another electrical switching device or trip unit
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