Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
  • G01R1/20—Modifications of basic electric elements for use in electric measuring instruments; Structural combinations of such elements with such instruments
  • G01R1/203—Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
  • G01R1/30—Structural combination of electric measuring instruments with basic electronic circuits, e.g. with amplifier
• • 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
  • G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
  • G01R19/2506—Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values ; Details concerning sampling, digitizing or waveform capturing

Definitions

• This invention relates to a current sensor intended for use in an electrical apparatus such as a residual current detection device, a current meter or a power meter.
• a current sensor comprising a metallic link member having two end portions of conductive material and an intermediate portion interconnecting the end portions, said intermediate portion being formed of a resistive material, and an integrated circuit analog to digital converter mounted on said link member, said converter having analog input terminals connected to respective ones of said two end portions and digital output terminals for connection to a processing apparatus.
• the converter is attached to the intermediate portion by a layer of electrically insulative adhesive material and the analog input terminals of the converter are connected to the end portions by wire bonds.
• the converter preferably includes a delta-sigma modulator which provides a high frequency one-bit digital data.
• One or more decimation filtering stages may be included in the converter.
• the converter may also have a voltage reference terminal for connection to a reference voltage source, the converter operating to provide digital output signals respectively representing the current flowing through said intermediate portion and digital output signals representing the voltage on one of said end portions.
• Figure 1 is a perspective view of one example of a current detector in accordance with the invention.
• Figure 2 is a sectional view of the detector
• Figure 3 is an elevation of the detector
• Figure 4 is a block diagram of a simple form of an electronic circuit for the detector
• FIGS 5 and 6 are block diagrams of more complex forms of electronic circuits.
• the detector shown in Figures 1 to 3 includes a rigid composite conductor strip having two end portions 13 of copper and an intermediate portion 14 of a resistive material such as manganin.
• the strips are formed by slicing up a sandwich formed by electron beam welding of the copper bars to opposite sides of a manganin bar.
• the shunts formed by the resistive portions 14 manufactured by this method may have a nominal resistance of 0.2m ⁇ to a tolerance of less than 5%.
• the resistance of adjacent slices from the sandwich may differ by as little as 2%.
• a signal pre-processing ASIC 15 is mounted on the manganin portion 14 by means of a layer of electrically insulating adhesive 16.
• Wire leads 17 connect two analog input terminals of the ASIC to respective ones of the copper end portions 13. Further leads connect terminals on the ASIC to conductors of a lead frame 18 parts of which are shown.
• the ASIC, the manganin portion, the wire leads and the lead frame conductors are all enclosed within a block 19 of electrically insulating encapsulation material for the protection thereof. Opposite ends of the copper end portions 13 project from the encapsulation block 19.
• the main block within the ASIC 15 consists of a single delta-sigma modulator 20.
• the output of the ASIC 15 in this case consists of a high frequency one-bit data signal train.
• the ASIC output is connected via a transformer or other isolation barrier 22 to a processor 23.
• the processor in this arrangement is configured to carry out one or more decimation filtering operations to convert the one-bit signal stream into a multi-bit digital valve at a lower frequency.
• the processor 23 may typically be configured to receive signals from a plurality of the detectors and to sum these signals to ascertain whether the current flows through the detectors are balanced. Such an arrangement can be used for residual current correction allowing an actuator to trip a switch if an unbalanced condition is found to exist.
• the processor 23 may alternatively or additionally compare the instantaneous current level with a trip level so that overcurrent tripping can be controlled.
• the ASIC is more complex and includes one or more of the decimation filtration stages 24 and a serial output driver 25 to transmit the bits of the multi-bit digital signal produced by the filtration stage 24 serially to the processor.
• the configuration of the processor can be simplified as part or all of the decimation filtration operation is carried out in the ASIC.
• the ASIC has a further analog input which can be connected to a reference voltage source.
• Two analog input stages 21 a and 21 b are present and these feed signals to two independent delta-sigma modulators 20a,20b.
• the outputs of the stages 22a,22b may, as shown, be connected to a common serial output stage or (not shown) separate serial output stages may be provided.
• Figure 6 may be modified by the omission of the two filtration stages 22a,22b where all filtration is to be carried out by the processor. Where voltage as well as current is monitored by the processor, precise calibration of the shunts can be achieved. This allows more accurate determination of the current balance in RCD applications. Moreover, as voltage and current are both being monitored to a high level of precision, accurate power consumption metering can be obtained.
• the processor can be programmed to recognise the transients which may occur when loads are switched in and out of circuit to avoid false tripping.
• Many other convenient functions can be programmed into the processor, made possible by the high precision of the current measurements capable of being carried out.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Measurement Of Current Or Voltage (AREA)
• Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
• Emergency Protection Circuit Devices (AREA)
• Switches That Are Operated By Magnetic Or Electric Fields (AREA)
• Arrangements For Transmission Of Measured Signals (AREA)
• Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
• Control Of Electric Motors In General (AREA)
• Protection Of Generators And Motors (AREA)

Priority Applications (12)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10834558

Family Applications (2)

Family Applications After (1)

Country Status (18)

Cited By (6)

Families Citing this family (31)

Citations (4)

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• 1998
  • 1998-06-30 GB GBGB9813982.7A patent/GB9813982D0/en not_active Ceased
• 1999
  • 1999-06-30 DE DE69904824T patent/DE69904824T2/de not_active Expired - Lifetime
  • 1999-06-30 CN CNB998081477A patent/CN1236318C/zh not_active Expired - Fee Related
  • 1999-06-30 CA CA002336018A patent/CA2336018C/en not_active Expired - Fee Related
  • 1999-06-30 GB GB0102014A patent/GB2357156B/en not_active Expired - Fee Related
  • 1999-06-30 CN CNB998081469A patent/CN1161620C/zh not_active Expired - Fee Related
  • 1999-06-30 KR KR1020007015087A patent/KR20010071700A/ko not_active Withdrawn
  • 1999-06-30 DE DE69912611T patent/DE69912611T2/de not_active Expired - Lifetime
  • 1999-06-30 ES ES99928134T patent/ES2189433T3/es not_active Expired - Lifetime
  • 1999-06-30 JP JP2000557153A patent/JP4326699B2/ja not_active Expired - Fee Related
  • 1999-06-30 AT AT99928134T patent/ATE230851T1/de active
  • 1999-06-30 US US09/720,683 patent/US6646430B1/en not_active Expired - Fee Related
  • 1999-06-30 AU AU45256/99A patent/AU770898B2/en not_active Ceased
  • 1999-06-30 NZ NZ508913A patent/NZ508913A/xx not_active IP Right Cessation
  • 1999-06-30 MY MYPI99002760A patent/MY121434A/en unknown
  • 1999-06-30 AU AU45250/99A patent/AU754847B2/en not_active Ceased
  • 1999-06-30 EP EP99928134A patent/EP1092158B1/en not_active Expired - Lifetime
  • 1999-06-30 NZ NZ508909A patent/NZ508909A/en not_active IP Right Cessation
  • 1999-06-30 US US09/720,782 patent/US6788067B1/en not_active Expired - Fee Related
  • 1999-06-30 DK DK99928134T patent/DK1092158T3/da active
  • 1999-06-30 AT AT99928140T patent/ATE253732T1/de active
  • 1999-06-30 EP EP99928140A patent/EP1092160B1/en not_active Expired - Lifetime
  • 1999-06-30 WO PCT/GB1999/002053 patent/WO2000000833A1/en not_active Ceased
  • 1999-06-30 KR KR1020007015086A patent/KR20010071699A/ko not_active Withdrawn
  • 1999-06-30 ES ES99928140T patent/ES2211106T3/es not_active Expired - Lifetime
  • 1999-06-30 GB GB0102016A patent/GB2357587B/en not_active Expired - Fee Related
  • 1999-06-30 PT PT99928134T patent/PT1092158E/pt unknown
  • 1999-06-30 WO PCT/GB1999/002060 patent/WO2000000834A1/en not_active Ceased
  • 1999-06-30 JP JP2000557154A patent/JP4416948B2/ja not_active Expired - Fee Related
  • 1999-06-30 MY MYPI99002761A patent/MY126429A/en unknown
  • 1999-06-30 CA CA002336015A patent/CA2336015C/en not_active Expired - Fee Related
  • 1999-07-28 TW TW088112772A patent/TW452651B/zh not_active IP Right Cessation
  • 1999-07-28 TW TW088112773A patent/TW438979B/zh not_active IP Right Cessation
• 2000
  • 2000-12-18 ZA ZA200007591A patent/ZA200007591B/en unknown
  • 2000-12-18 ZA ZA200007592A patent/ZA200007592B/en unknown

Patent Citations (4)

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