GB2519342A - Detection of circuit integrity - Google Patents

Detection of circuit integrity Download PDF

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Publication number
GB2519342A
GB2519342A GB1318445.2A GB201318445A GB2519342A GB 2519342 A GB2519342 A GB 2519342A GB 201318445 A GB201318445 A GB 201318445A GB 2519342 A GB2519342 A GB 2519342A
Authority
GB
United Kingdom
Prior art keywords
component
circuit
temperature
integrity
sensing
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
GB1318445.2A
Other versions
GB201318445D0 (en
Inventor
William Henry Gardiner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
HEBER Ltd
Original Assignee
HEBER Ltd
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
Application filed by HEBER Ltd filed Critical HEBER Ltd
Priority to GB1318445.2A priority Critical patent/GB2519342A/en
Publication of GB201318445D0 publication Critical patent/GB201318445D0/en
Publication of GB2519342A publication Critical patent/GB2519342A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K13/00—Thermometers specially adapted for specific purposes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K3/00—Thermometers giving results other than momentary value of temperature
    • G01K3/08—Thermometers giving results other than momentary value of temperature giving differences of values; giving differentiated values
    • G01K3/10—Thermometers giving results other than momentary value of temperature giving differences of values; giving differentiated values in respect of time, e.g. reacting only to a quick change of temperature
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • G01K7/22—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/145—Indicating the presence of current or voltage
    • G01R19/15—Indicating the presence of current
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

An apparatus is disclosed for sensing the integrity of an electrical circuit, the apparatus comprising a first electrical component 14, the temperature of which changes upon the application of a current and which is operable upon application of the current. It further comprises a sensor component 20, e.g. a thermistor, operable to detect a change in temperature of the first component 14. The first component can either be an integral part of the circuit or an additional component incorporated into the circuit specifically to detect the operational integrity of the circuit. The apparatus may further comprise a switching means to switch in and out the first component.

Description

DETECTION OF CIRCUIT INTEGRITY
This invention relates to a method and apparatus for use in detecting or sensing the integrity of an electrical circuit, for example to ascertain whether or not a load is present therein or is connected thereto.
It is often desirable to be able to detect or sense whether an electrical circuit is operating correctly or as expected so that in the event of a fault, appropriate diagnostic techniques can be used to identify the fault and allow the repair or replacement of appropriate parts of the circuit to allow continued use thereof. The provision of means permitting such detection or sensing is especially advantageous in circumstances in which the circuit can continue to operate in its failed or faulty condition, as it may not be apparent to a user that the failure has occurred, and use of the circuit may continue until a subsequent catastrophic failure occurs. If the original fault can be detected, then it may be possible to repair the circuit at a convenient time, thereby avoiding the occurrence of a situation in which a device of which the circuit forms part is unexpectedly unavailable for use, potentially for an extended period of time, until such time as the circuit can be repaired or replaced. By way of example, repair may be undertaken as part of a scheduled maintenance operation if the presence of the fault can be readily detected.
One technique used in the detection of whether or not a circuit is functioning correctly involves checking for the existence of an open cilcuit load and lepoiting the existence of a fault condition in the event that such a load is sensed. The method or technique used in detecting the presence of such a load may involve introducing an appropriate series impedance into the circuit, applying a test voltage to the relevant part of the circuit and monitoring for a corresponding current flow through the impedance, or voltage drop across the impedance. In order to avoid excessive power dissipation, the voltage drop across the impedance must be very small, and so the sensing circuit used to monitor for the presence of the voltage drop must be of good sensitivity.
Where the technique outlined above is used in detecting or sensing the integrity of high voltage circuits, then it may be necessary to power the sensing circuit independently of the normal power supply for the circuit to maintain the electrical isolation therebetween.
The requirement to provide additional power supplies to operate the sensing circuit and S to inject the test voltage into the circuit adds significantly to the cost, size and complexity of the overall circuit, which is disadvantageous.
It is an object of the invention to provide an alternative method and apparatus for use in sensing or detecting the integrity of a circuit in which at least some of the disadvantages with known arrangements are overcome or are of reduced effect.
According to the present invention there is provided an apparatus for sensing the integrity of an electrical circuit comprising a first electrical component, the temperature of which changes upon the application of a current thereto to cause operation thereof, and a sensor component operable to detect a change in temperature of the first component.
The first component may comprise an integral part of the circuit, the integrity of which is being monitored. Alternatively, the first component may be an additional component incorporated specifically to allow the operation of or integrity of the circuit to be sensed.
The apparatus may include switch means operable to switch in and out the first component. Depending upon the nature of the first component and whether or not the first component forms an integral part of the electrical circuit being monitored, such switch means may also form an integral part of the electrical circuit. Alternatively, the switch means may comprise an additional component provided purely to permit the operation of the invention.
It will be appreciated that, in such an arrangement, by switching in or otherwise applying a current to the first component to cause a change in temperature thereof, and by detecting the change in temperature, an indication can be provided regarding the integrity of the circuit of which the first component is part or with which it is associated as the change in temperature indicates that the first component is live. The absence of a change in temperature indicates that a fault is present as the first component is not operating at a point in time when operation thereof is expected.
The invention also relates to a method of sensing the integrity of a circuit comprising applying a current to a first component the temperature of which changes upon the application of a current thereto to cause the operation thereof, and sensing a change in the temperature of the first component. In such an arrangement, the sensing of a change in temperature provides an indication that the circuit is functioning normally.
The invention will further be described, by way of example, with reference to the accompanying drawing, Figure 1, which is a schematic circuit diagram illustrating an apparatus in accordance with one embodiment of the invention.
Referring to Figure 1, a circuit 10 is illustrated which comprises a device 12 the operation of which is controlled by first and second switching devices 14, 16. By way of example, the device 12 may be switched on by the operation of the first switching device 14 which may comprise a triac or the like. Once the device 12 is switched on, it may be maintained in its on condition by the second switching device 16 which may take the form of a relay or the like. The first switching device 14 can thus be by-passed after the initial switching on of the device 12 by the operation of the second switching device 16, possibly in conjunction with the opening of, for example, a further switch 14a. However, depending upon the nature of the first switching device 14, the operation thereof may be such that there is no requirement to provide the further switch 14a. Such a switching arrangement may be thought to be advantageous in that the impedance of a triac once switched on is typically high, and so continued operation of the circuit with the triac in its on condition will result in excessive power dissipation and heat generation. The ability to by-pass' the triac by the operation of the second switching device 16 or relay providing a low impedance path, or where a further switch 14a is provided, by the opening thereof, thus allows operating efficiency savings to be made.
In accordance with the invention, an apparatus 18 is provided in order to allow sensing or detection of the operating integrity of the circuit 10. The apparatus 18 comprises a first component, the temperature of which varies upon the application of an electrical current thereto. In the arrangement illustrated, the first component takes the form of the first switching device 14 of the circuit 10 and so forms an essential part of the operation of the circuit 10. As described above, operation of the switch 14a (where provided) disconnects the first component/first switching device 14 from the remainder of the circuit 10.
The apparatus 18 further comprises a sensor component operable to monitor or be otherwise sensitive to the temperature of the first component, or to changes in the temperature of the first component. In the arrangement illustrated the sensing component comprises a thermistor 20 located adjacent or in the vicinity of the first component/first switching device 14. The resistance of the thermistor 20 varies in a known relationship with the temperature thereof, and by placing the thermistor 20 close to the first component/first switching device 14 it will be appreciated that the resistance of the thermistor 20 can be used to provide an indication of the temperature of the first component/first switching device 14. A meter 22 is provided to monitor the resistance of the thermistor 20 and thus output a signal indicative of the temperature of the thermistor 20 and first component/first switching device 14.
As mentioned above, in normal use, the first switching device 14 is switched to its on' position for a short period of time in order to control the switching on of the device 12.
When in its on' position the temperature of the first switching device 14 rapidly rises.
As the thermistor 20 is located adjacent or in the vicinity of the first switching device 14, the temperature of the thermistor 20 also rises, resulting in a corresponding change in the resistance thereof which is detected by the meter 22, thereby providing an indication that the circuit is operating as expected.
In the event of a failure which causes the first switching device 14 to become inoperable, for example a failure of the first switching device 14 itself, or a failure in the control arrangement whereby the operation of the first switching device 14 is controlled, or a failure in the electrical connections to the first switching device 14, the temperature S of the first switching device 14 will not rise at the point in time at which it is supposed to be occupying its on position. By monitoring the resistance of the thermistor 20 and noting that the resistance does not change, thereby providing an indication that the temperature of the first switching device 14 has not changed, an indication can be provided to the effect that the circuit has failed.
In the circuit described hereinbefore, the first switching device 14 is arranged to be by-passed after a relatively shod operating period by operation of the second switching device 16, thus the temperature rise which is sensed and used to provide an indication that the circuit is operating normally only occurs for a relatively short period of time.
Where the further switch 14a is provided, then the opening of that switch may control the point at which the first switching device 14 is by-passed. In other applications, the first component, the temperature of which is monitored to provide an indication of the integrity of the circuit may be arranged to be operated for longer periods of time or throughout the operation of the circuit. In such arrangements, it may be, for example, the initial temperature rise which is used to provide an indication that the circuit is operational, or the elevated temperature attained by the first component when operational may be monitored.
The apparatus and method described hereinbefore are advantageous in that the sensing circuitry is electrically isolated from the circuit 10. Detection of a temperature change can be undertaken reliably using only a few low cost components, thus the invention can be implemented in a simple and economic manner.
In the arrangement described hereinbefore the first component forms an integral part of the circuit 10, essential to the operation thereof, and the switch 14a used in controlling the operation of the first component also forms an integral part of the circuit, essential to the normal operation thereof It will be appreciated that this need not always be the case. By way of example, if a circuit includes a component, the operation of which it is desired to monitor, but the temperature of which does not change in use thereof, then it may be desirable to incorporate an impedance in the circuit, either in series with the component or parallel therewith, and to monitor changes in temperature of the S impedance to provide an indication as to whether or not the component is live. If it is desired for the component to be live for only a short period of time, then the associated control or switch arrangement which controls the operation of the component can also control the operation of the impedance (ie whether or not a voltage is applied thereto).
If it is desired to disconnect the impedance whilst the component is still live, having ascertained that the circuit is operating as expected, then an additional switch may be provided to allow separate control of the operation of the impedance. For such an arrangement to operate, the impedance may be arranged in parallel with the component, or a by-pass may be provided to ensure that switching out of the impedance does not impact upon the operation of the circuit as a whole.
It will be appreciated that whilst certain specific embodiments of the invention are described hereinbefore, a wide range of modifications and alterations may be made thereto without departing from the scope of the invention as defined by the appended claims.

Claims (11)

  1. CLAIMS: 1. An apparatus for sensing the integrity of an electrical circuit comprising a first electrical component, the temperature of which changes upon the application of a current thereto to cause operation thereof, and a sensor component operable to detect a change in temperature of the first component.
  2. 2. An apparatus according to Claim 1, wherein the first component comprises an integral part of the circuit, the integrity of which is being monitored.
  3. 3. An apparatus according to Claim 1, wherein the first component is an additional component incorporated into the circuit specifically to allow the operation of or integrity of the circuit to be sensed.
  4. 4. An apparatus according to any of the preceding claims, further comprising switch means operable to switch in and out the first component.
  5. 5. An apparatus according to Claim 4, wherein the switch means comprises an integral part of the circuit, the integrity of which is being monitored.
  6. 6. An apparatus according to Claim 4, wherein the switch means comprise an additional component provided specifically to allow the operation of or integrity of the circuit to be sensed.
  7. 7. An apparatus according to any of the preceding claims, wherein the sensor component comprises a component the resistance of which is dependent upon the temperature thereof.
  8. 8. An apparatus according to Claim 7, wherein the sensor component comprises a thermistor.
  9. 9. An apparatus according to Claim 7 or Claim 8, further comprising means for sensing the resistance of the sensor component.
  10. 10. A method of sensing the integrity of a circuit comprising applying a current to a first component the temperature of which changes upon the application of a current thereto to cause the operation thereof, and sensing a change in the temperature of the first component.
  11. 11. A method according to Claim 10 and using the apparatus of any of Claims ito 9.
GB1318445.2A 2013-10-18 2013-10-18 Detection of circuit integrity Withdrawn GB2519342A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1318445.2A GB2519342A (en) 2013-10-18 2013-10-18 Detection of circuit integrity

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1318445.2A GB2519342A (en) 2013-10-18 2013-10-18 Detection of circuit integrity

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GB201318445D0 GB201318445D0 (en) 2013-12-04
GB2519342A true GB2519342A (en) 2015-04-22

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GB (1) GB2519342A (en)

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3967169A (en) * 1974-01-05 1976-06-29 Ellenberger & Poensgen Gmbh Switching device for the protection of direct current devices
JPS60176076A (en) * 1984-02-23 1985-09-10 Fuji Xerox Co Ltd Fault detecting device of fixing device for electronic copying machine
EP1408594A2 (en) * 2002-10-10 2004-04-14 Sanyo Electric Co. Ltd DC ground fault detector and system-interconnected generation device using the DC ground fault detector
JP2006136161A (en) * 2004-11-08 2006-05-25 Panasonic Ev Energy Co Ltd Contactor fault detecting apparatus of electric motor-driven vehicle, method of detecting contactor fault, program and computer-readable recording medium
US20080055799A1 (en) * 2006-08-31 2008-03-06 Yazaki Corporation Apparatus and method for detecting abnormal conditions of a motor
JP2009051255A (en) * 2007-08-23 2009-03-12 Nsk Ltd Control device of electric power steering device
US20090296777A1 (en) * 2008-05-30 2009-12-03 General Electric Company Method and apparatus for detecting a fault in a brushless exciter for a generator
JP2010032395A (en) * 2008-07-29 2010-02-12 Tdk-Lambda Corp Contact failure detection device and switching power source
US20110141635A1 (en) * 2009-12-10 2011-06-16 Fabian Steven D Thermally protected GFCI
JP2013198256A (en) * 2012-03-19 2013-09-30 Toyota Motor Corp Electric vehicle

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3967169A (en) * 1974-01-05 1976-06-29 Ellenberger & Poensgen Gmbh Switching device for the protection of direct current devices
JPS60176076A (en) * 1984-02-23 1985-09-10 Fuji Xerox Co Ltd Fault detecting device of fixing device for electronic copying machine
EP1408594A2 (en) * 2002-10-10 2004-04-14 Sanyo Electric Co. Ltd DC ground fault detector and system-interconnected generation device using the DC ground fault detector
JP2006136161A (en) * 2004-11-08 2006-05-25 Panasonic Ev Energy Co Ltd Contactor fault detecting apparatus of electric motor-driven vehicle, method of detecting contactor fault, program and computer-readable recording medium
US20080055799A1 (en) * 2006-08-31 2008-03-06 Yazaki Corporation Apparatus and method for detecting abnormal conditions of a motor
JP2009051255A (en) * 2007-08-23 2009-03-12 Nsk Ltd Control device of electric power steering device
US20090296777A1 (en) * 2008-05-30 2009-12-03 General Electric Company Method and apparatus for detecting a fault in a brushless exciter for a generator
JP2010032395A (en) * 2008-07-29 2010-02-12 Tdk-Lambda Corp Contact failure detection device and switching power source
US20110141635A1 (en) * 2009-12-10 2011-06-16 Fabian Steven D Thermally protected GFCI
JP2013198256A (en) * 2012-03-19 2013-09-30 Toyota Motor Corp Electric vehicle

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Publication number Publication date
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