Fluke A40B Instruction Manual
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Fluke A40B Instruction Manual

Fluke A40B Instruction Manual

Precision ac current shunt set
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Via Acquanera, 29
22100 Como
tel. 031.526.566 (r.a.) fax 031.507.984
info@calpower.it
www.calpower.it
July 2008 Rev. 1, 7/09
© 2008-2009 Fluke Corporation. All rights reserved. Specifications are subject to change without notice.
All product names are trademarks of their respective companies.
A40B
Precision AC Current Shunt Set
Instruction Manual

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  • Page 1 031.526.566 (r.a.) fax 031.507.984 info@calpower.it www.calpower.it A40B Precision AC Current Shunt Set Instruction Manual July 2008 Rev. 1, 7/09 © 2008-2009 Fluke Corporation. All rights reserved. Specifications are subject to change without notice. All product names are trademarks of their respective companies.
  • Page 2 Fluke authorized resellers shall extend this warranty on new and unused products to end-user customers only but have no authority to extend a greater or different warranty on behalf of Fluke. Warranty support is available only if product is purchased through a Fluke authorized sales outlet or Buyer has paid the applicable international price.

  • Page 3: Table Of Contents

    Operating Information ..................10 Feature Descriptions..................10 Input/Output Connectors ................12 Maximum Current ..................13 Operating Environment ................. 13 Correcting for Current Shunt Error Contributions ........13 Output Voltage Measurement – Loading Effect..........14 Output Voltage Measurement Using a Fluke 5790A ........14...
  • Page 4 A40B Instruction Manual Output Voltage Measurement Using a Fluke 8508A ........15 Operating Instructions..................16 Introduction ....................16 Measuring Current..................16 Direct Read-out When Measuring Current............ 18 Theory of Operation................... 18 Coaxial Shunts....................18 Boxed Shunts....................19 Introduction ....................20 An Overview of Calibration Methods ............
  • Page 5 Estimating the Uncertainty of a 5790A Measurement ........... 17 Sample Calculation of Measured Current .............. 17 Single Junction Thermal Voltage Converters ............21 Fluke 792A AC/DC Transfer Standard ..............21 Fluke 5790A Measurement Standard ..............22 Other Error Sources and Solutions................. 23 List of Recommended Equipment................
  • Page 6 A40B Instruction Manual...
  • Page 7 Current Shunt - Simplified Electrical Diagram............19 Circuit Using a Reference Shunt Resistor to Determine Source Current....20 Sources of Error in AC Measurements ..............23 The Fluke Calibration System................24 Calibrating Gain Difference ................... 25 Characterizing Sensitivity ..................26 AC/DC Difference Sequence .................
  • Page 8 A40B Instruction Manual...

  • Page 9: Introduction And Specifications

    Introduction and Specifications About the Manual This is the Instruction Manual for the A40B Precision AC Current Shunt Set (hereafter referred to as the Current Shunt or Current Shunts). It contains all of the information a Calibration Technician needs to operate and maintain the Current Shunts. The manual is divided into the following sections: •...

  • Page 10: Symbols

    The following safety and electrical symbols may appear on the Current Shunt or in this manual. Do not dispose of this product as unsorted Risk of danger. municipal waste. Go to Fluke’s website for Important information. See manual. recycling information. DC (Direct Current) Warning.

  • Page 11: Product Description

    Introduction and Specifications Product Description The A40B Precision AC Current Shunt Set consists of 14 Current Shunts, a complement of adapters, and a rugged transit/storage case. The Current Shunts are designed for laboratory use in making AC-DC current measurements or absolute AC or DC current measurements.

  • Page 12: Electrical Specifications

    A40B Instruction Manual Electrical Specifications Current Shunt Absolute Accuracy The following table shows the 1-year absolute accuracy specification stated at k=2, approximately 95% confidence for the calibrated value. The specifications include 1-year stability, temperature effects over TCal ± 1 °C, and the measurement uncertainty of the calibrated value.

  • Page 13: Resistance Specifications

    Precision AC Current Shunt Set Electrical Specifications Resistance Specifications Uncertainty of Maximum Calibrated Power Nominal Deviation 12 Month Temperature Shunt Nominal Value at 95% Coefficient Resistance from Nominal Stability Coefficient Current Confidence Multiplier [1][2] (Ohms) Resistance (±ppm/ºC) (±μΩ/Ω) [2][3] (±ppm) (±μΩ/Ω) TCal (±μΩ/Ω) ±1ºC...

  • Page 14: Maximum Ac-Dc Difference

    A40B Instruction Manual Maximum AC-DC Difference [1][2] Maximum AC-DC Difference (±ppm) Shunt Nominal Current 1 kHz 10 kHz 30 kHz 100 kHz 1 mA 10 mA 20 mA 50 mA 100 mA 200 mA 500 mA 10 A 20 A...

  • Page 15: General Specifications

    Precision AC Current Shunt Set General Specifications General Specifications Dimensions (maximum) Height Width Overall Length Shunt Value mm (inches) mm (inches) mm (inches) 1 mA to 2 A 70 (2.75) 70 (2.75) 124 (4.9) 5 A to 20 A 130 (5) 130 (5) 210 (8.25) 50 A and 100 A...

  • Page 16: Preparing For Operation

    If there is any sign of physical damage, notify the carrier immediately. As part of the inspection process, check the contents against the list shown in Table 1. Report any shortages to the nearest Fluke Technical Service Center. See Contacting Fluke.

  • Page 17: Contacting Fluke

    General Maintenance/Cleaning. Repair any damage before proceeding. Instructions for contacting Fluke are provided earlier in this manual. 2. Functionally test each Current Shunt by applying the nominal current to its input. At nominal current, the output voltage for each Current Shunt should be approximately 0.8 volts.

  • Page 18: General Maintenance/Cleaning

    (see MIL-C-39012 for details). Defective connectors can be replaced but it is recommended the work be performed at a Fluke Service Center. Operating Information This section of the manual contains practical information the user needs to know before and after making a current measurement.
  • Page 19 Precision AC Current Shunt Set Operating Information Rear Front Passive Shunt (100 mA) Bottom Active Shunt (1 mA) fim005.eps Figure 2. Features and Connectors...

  • Page 20: Input/Output Connectors

    The inductance can also burden current sources beyond their capability. To help counter the effect, make sure the current connections are coaxial and as short as possible. A defective connector on a Current Shunt is replaceable. However, Fluke recommends the work be done at a Fluke Service Center.

  • Page 21: Maximum Current

    Precision AC Current Shunt Set Operating Information Maximum Current Each Current Shunt is marked at the input connector with its nominal (rated) current. Similarly, markings at the voltage output connector indicate the nominal voltage out for nominal current in. A table in the specifications section provides maximum currents to maintain performance and to avoid irreversible damage.

  • Page 22: Output Voltage Measurement - Loading Effect

    Figure 3. Loading Effect of the Measurement Device Output Voltage Measurement Using a Fluke 5790A The typical input impedance of a 5790A (input 1 or 2) is >10 MΩ (dc) in parallel with 70 pF. The 10 MΩ in parallel with the shunt resistance has a small effect on the lowest current value Current Shunts at DC.

  • Page 23: Output Voltage Measurement Using A Fluke 8508A

    Precision AC Current Shunt Set Output Voltage Measurement Using a Fluke 8508A The input impedance of an 8508A on its DC function is >10 GΩ and the loading effect for measuring DC current with any Current Shunt is negligible. The typical AC function (DC coupled) low frequency input impedance of an 8508A is 1 MΩ...

  • Page 24: Operating Instructions

    A40B Instruction Manual Operating Instructions Introduction This section of the manual describes how to measure both AC and DC current using any one of the Current Shunts. The procedures are based on the assumption that the user is familiar with the Operating Information and Specifications presented earlier in this manual.
  • Page 25 200 mA at 1 kHz, as documented in the 5720A's full verification procedure. Source: Fluke 5720A – 200 mA output at 1 kHz Measurement Equipment: Fluke Current Shunt, 200 mA (calibrated at 23 °C) and a Fluke 5790A Make the measurement and estimate the uncertainty using the information given in Table 6.

  • Page 26: Direct Read-Out When Measuring Current

    For Example: In the following scenario, a current source is measured with a 100 mA Current Shunt and a Fluke 8508A. Assumptions: • Calibrated DC resistance of the Current Shunt (z) = 7.999600 •...

  • Page 27: Boxed Shunts

    Precision AC Current Shunt Set Theory of Operation Current Input Voltage Output Connector - Inner Connector - Inner Current Input Segment Top Connector - Outer Side Copper Segment Bottom Side Copper Bulk Foil Resistor feh006.png Figure 4. Current Shunt - Simplified Electrical Diagram The PCB designated A in Figure 4 is copper clad on both sides.

  • Page 28: Introduction

    Neither of the descriptions contains detailed step by step procedures for calibrating the Current Shunts. Rather, the descriptions are meant to provide a foundation for the seasoned calibration technician to work with and use the Fluke method of calibrating Current Shunts.

  • Page 29: Potential Voltage Measurement Devices

    (draughts, heat source) Fluke 792A AC-DC Transfer Standard The Fluke 792A can be used to make AC-DC difference measurements and has many advantages over the SJTVC. See Table 9. It does, however, have one disadvantage that reduces its usefulness for this application. Unlike the single junction TVC, the 792A is subject to common-mode interference, particularly when used as the measurement device for the Reference Standard shunt.

  • Page 30: Dc Considerations

    The Reference Shunt is also a 10 mA Current Shunt, but its voltage is measured with a Fluke 792A, 700 mV range – input impedance more than 10 MΩ. The entire 10 mA current generated by the source passes through the Reference Shunt. Because of the shunting effect of the SJTVC, 6.7 mA flows in the UUT and 3.3 mA flows in the SJTVC;...

  • Page 31: Ac Considerations

    Devices with active input circuits generally have high input resistance and capacitance becomes more influential on frequency flatness. Tables 4, 5, and 6 provide typical values and errors for Fluke 5790A and 792A.

  • Page 32: The Fluke Calibration Method

    The Fluke Calibration Method The Fluke calibration method makes automated AC-DC difference and DC Resistance measurements. See Figure 7. The voltage outputs from the reference and UUT shunts are each detected with a 0.8 V, 5 mA SJTVC and a Keithley 2182A nanovoltmeter. A single manual intervention during the calibration disconnects the TVC assemblies and connects the shunt outputs to the nanovoltmeter secondary inputs.

  • Page 33: Recommended Tools And Equipment

    Nanovoltmeter 1 TVC assy Keithley 2182A Digital SJTVC Nanovoltmeter 2 feh020.eps Figure 8. Calibrating Gain Difference The Fluke 5720A produces an output of 0.8 V. The relative AC-DC difference of the SJTC assemblies is measured and applied as a correction.

  • Page 34: Tvc Sensitivity Characterization

    A40B Instruction Manual TVC Sensitivity Characterization The voltage output of a SJTVC output is proportional to the square of the applied voltage. Thus the device is inherently non-linear and transresistance gain or sensitivity changes with input current. Sensitivity characterization minimizes the resulting errors by determining mean sensitivity in a narrow band ±500 ppm from the nominal current.

  • Page 35: Uut Ac-Dc Difference Measurement Sequence And Calculations

    Precision AC Current Shunt Set Theory of Operation UUT AC-DC Difference Measurement Sequence and Calculations In order to minimise the effects of drift, the measurement sequence is symmetrical in the form AC1, +DC, -DC, AC2. The ±DC measurements cancel thermal emf and zero offset. The two AC measurements compensate for drift during the measurement.

  • Page 36: Current Source Dc Noise

    = Gain sensitivity of the Reference Standard measurement system Current Source DC Noise From some transconductance amplifiers, noise on DC can be problematic. The Fluke system addresses this problem by triggering the two nanovoltmeters at the same time so they integrate simultaneously to maximize noise immunity.

  • Page 37: Repair Procedures Including Disassembly And Reassembly

    The N-type connectors of the 10 mA, 20 mA and 50 mA boxed Current Shunts can be replaced after removing the cover plate on the underside, but it is recommended the Current Shunts be returned to a Fluke Service Center for repair. Other than battery replacement, do not attempt to service the 1 mA Current Shunt.

  • Page 38: End Plates And Guard Binding Post Replacement (Coaxial Shunts)

    A40B Instruction Manual End Plates and Guard Binding Post Replacement (Coaxial Shunts) Note The end plates have a small affect on the magnetic fields in the Current Shunt and should always be in place during operation of the Current Shunt.

  • Page 39: Input N-Type Connector Replacement (Coaxial Shunts)

    Precision AC Current Shunt Set Repair Procedures Including Disassembly and Reassembly Input N-type Connector Replacement (Coaxial Shunts) Use the following procedure to replace the type-N input connector: 1. Remove the input end plate (Figure 11- F ). 2. Remove the 3 mm screws, nuts and washers shown in Figure 11. 3.

  • Page 40: Output N-Type Connector Replacement (Coaxial Shunts)

    A40B Instruction Manual Output N-Type Connector Replacement (Coaxial Shunts) Use the following procedure to replace the N-type output connector: 1. Remove the output end plate (Figure 11- D ). 2. Remove the 3 mm screws, nuts and washers from the N-type connector.

  • Page 41: List Of Replaceable Parts

    List of Replaceable Parts User service is limited to replacing the parts identified in Figure 14 and listed in Table 13. To order replacement parts refer to Contacting Fluke earlier in this manual. feh009.eps Figure 14. Final Assembly – Typical Current Shunt from the Set Table 13.
  • Page 42 A40B Instruction Manual Via Acquanera, 29 22100 Como tel. 031.526.566 (r.a.) fax 031.507.984 info@calpower.it www.calpower.it...

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