IET Labs Inc. 1616 Test Set
Manufacturer:
Model:
1616
Date:
2001
Category:
Group:
Description:
Precision Capacitance Bridge
Information
The 1621 Capacitance-Measurement system is designed for the precise measurement of capacitors and capacitance standards. In the standards laboratory, its high resolution for capacitance and conductance make this system well suited for capacitance standards measurements. Its phase-indicating error meters facilitate rapid balancing. Convenient in-line readout maximizes accuracy of manual data recording and BCD outputs are provided for automatic data processing. The 1621 system measures either 3-terminal or 2-terminal capacitors. The transformer-ratio-arm circuitry of the bridge assures that 3-terminal measurements can be made accurately, even in the presence of large capacitances to ground. For instance, a ground capacitance of 1 ;uF produces an error of only 0.03% in the measurement of 1000-pF capacitor. This feature makes the assembly very useful for in situ measurements of ungrounded circuit capacitances. The 1616 Precision Capacitance Bridge, one of the 3 instruments in that system, may be obtained separately. The bridge will perform as described herein, if used with an Oscillator and detector equivalent to the CiR 1316 and 1238. NOTE This manual describes the 1621 system generally and provides its operating instructions. This manual also describes in detail the 1616 bridge only. A wide range of capacitances can be measured, extending from the resolution limit of 0.1 aF (10‘7pF) to a maximum of 10 /if, with internal standards, or farther with external standards. For 3-terminal unknown capacitors, a pair of coaxial terminals is provided; for 2-terminal coaxial "unknowns," a single precision connector facilitates exacting control of fringing effects. Since an important use of this bridge is the comparison of capacitance standards, another pair of coaxial terminals is provided on the bridge to which a 3-terminal reference standard can be connected and designated EXTERNAL STANDARD. The other standard is then connected to the selected UNKNOWN terminals, and the internal standards are used to complete the balance. If the ratio between the two standards is close to 0.1, 1., or 10, the accuracy of the measurement is equal to the accuracy of calibration of the reference standard, and the precision of comparison is 1 part in 10s (0.01 ppm) of a 10-pF capacitor (or even better for larger ones). 1.2 DESCRIPTION. Figure 1-1. 1.2.1 General. The 1621 Precision Capacitance-Measurement System consists of the 1616 Precision Capacitance Bridge with the 1316 Oscillator and the 1238 Detector, a complete system for the precise measurement of capacitance. Oscillator and detector are mounted above the bridge, in a pedestal cabinet, as pictured in the front pages (and Figure 1-2); or the three instruments may be rack mounted. Connecting cables, supplied, go neatly behind the assembly.

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Service and User Manual
Manual type:
Service and User Manual
Pages:
94
Size:
20.00 Mbytes (20969728 Bytes)
Language:
english
Revision:
Manual ID:
Date:
01 January 2001
Quality:
Scanned document, all readable.
Upload date:
04 February 2017
MD5:
0f18a413ef05df8c38d797519e504826
Downloads:
274
Information
CONDENSED OPERATING INSTRUCTIONS . ix SPECIFICATIONS ... x 1 INTRODUCTION 1.1 Purpose ... 1-1 1.2 Description ... 1-1 1.2.1 General ... 1-1 1.2.2 Bridge Circuit ... 1-1 1.2.3 Standards ... 1-2 1.2.4 Oscillator ... 1-2 1.2.5 Detector ... 1-2 1.3 Controls, Indicators, and Connections ... 1-3 1.4 Accessories ... 1-3 2 INSTALLATION 2.1 General ... 2-2 2.2 Dimensions ... 2-3 2.3 Environment ... 2-2 2.4 Bench Models ... 2-2 2.4.1 Cabinet Removal ... 2-2 2.4.2 Conversion For Rack Mounting ... 2-2 2.5 Rack Models ... 2-2 2.5.1 General ... 2-3 2.5.2 Installation ... 2-3 2.5.3 Conversion To Bench Use .. 2-3 2.6 Power-Line Connection ... 2-4 2.7 Line-Voltage Regulation ... 2-4 2.8 System Connections ... 2-4 2.8.1 Oscillator, Bridge, and Detector ... 2-4 2.8.2 BCD-Capacitance-Output Connector ... 2-4 2.8.3 BCD-Conductance-Output Connector ... 2-5 2.8.4 Analog Outputs ... 2-5 3 OPERATION 3.1 Preliminary Checks ... 3-1 3.2 Functional Self-Checks ... 3-1 3.3 Phase Adjustment ... 3-2 Section Page 3.4 Connection of Unknown Capacitor . 3-3 3.4.1 Three-Terminal Capacitors . 3-3 3.4.2 Two-Terminal Coaxial Capacitors ... 3-3 3.5 Balance and Readout ... 3-4 3.5.1 Readout Multiplier ... 3-4 3.5.2 Initial Settings of Lever Switches ... 3-5 3.5.3 Balance Procedures ... 3-5 3.5.4 Final Balance ... 3-6 3.5.5 Readout Correction ... 3-7 3.5.6 Units of Measurement ... 3-7 3.6 Parameters of The Unknown Capacitor ... 3-7 3.6.1 Series Equivalent Parameters ... 3-7 3.6.2 Dissipation Factor ... 3-8 3.7 Frequency ... 3-8 3.7.1 Setting The Frequency ... 3-8 3.7.2 Monitoring Frequency ... 3-8 3.7.3 Locking To a Frequency Reference ... 3-10 3.8 Voltage Level ... 3-10 3.9 Accuracy ... 3-10 3.9.1 Accuracy Versus Frequency and Cx ... 3-10 3.9.2 Accuracy Versus Temperature ... 3-11 3.9.3 Range and Dissipation Factor Limitations ... 3-12 3.9.4 Shunt Capacitance To Ground ... 3-12 3.9.5 Fringing Capacitance ... 3-13 3.9.6 Conductance Accuracy ... 3-14 3.10 Precision ... 3-15 3.11 External Standards ... 3-15 3.11.1 Range Extension To 111 Microfarads ... 3-15 3.11.2 Extension of C Resolution .. 3-16 3.11.3 Externally Determined Accuracy/ Comparisons ... 3-16 3.11.4 Test-Fixture Compensation . 3-17 3.11. 5 Range Extensions To 11 Microsiemans ... 3-17 3.12 Precise Comparisons ... 3-17 3.12.1 Balance Comparisons ... 3-17 3.12.2 Direct Substitution ... 3-17 3.13 Non-coaxial 2-Terminal Capacitors . 3-17 3.13.1 Unshielded 2-Terminal Capacitors ... 3-18 3.13.2 Shielded 2-Terminal Capacitors ... 3-18 3.14 Dc Bias ... 3-20 3.14.1 Normal Bridge Configuration/ Parallel Bias ... 3-21 3.14.2 Reversed Bridge Configuration/ Series Bias ... 3-21 3.14.3 Dc In The Ratio Transformer/ Demagnetization ... 3-22 3.15 Reversed Configuration ... 3-22 3.15.1 Explanation ... 3-22 3.15.2 Procedure ... 3-22 4 THEORY 4.1 Introduction ... 4-1 4.2 Properties of Capacitors ... 4-1 4.2.1 Basic Components of Capacitance ... 4-1 4.2.2 Inductive and Lossy Components ... 4-2 4.2.3 Frequency Characteristics .. 4-4 4.3 Basic Bridge Circuitry ... 4-5 4.3.1 Elementary Capacitance Bridges ... 4-5 4.3.2 Transformer-Ratio Bridges . 4-5 4.4 Circuitry of The 1616 Bridge ... 4-7 4.4.1 Excitation ... 4-7 4.4.3 Capacitance Standards ... 4-7 4.4.4 Conductance Standards ... 4-8 4.4.5 External Standards ... 4-9 4.4.6 Zero Adjust ... 4-9 4.5 C-Standards Accuracy ... 4-9 4.5.1 Calibration ... 4-9 4.5.2 Sealing ... 4-10 4.5.3 Thermal Lag ... 4-10 Section Page 4.6 G-Standards Accuracy ... 4-9 4.7 Ratio Accuracy ... 4-11 4.7.1 Residual Impedances ... 4-11 4.7.2 Example With 1:1 Ratio ... 4-12 4.7.3 The 10:1 Ratio ... 4-13 4.7.4 The 1:100 Ratio ... 4-13 4.7.5 C Offset Due To Induction . 4-14 4.7.6 Ground Circuit Impedance . 4-14 5 SERVICE and DIAGRAMS 5.1 GR Field Service ... 5-1 5.2 Minimum Performance Standards .. 5-1 5.2.1 General ... 5-1 5.2.2 Zero Setting, Offsets, and Sensitivity ... 5-3 5.2.3 Capacitance Accuracy ... 5-3 5.2.4 Capacitance Ratios ... 5-3 5.2.5 Conductance Accuracy ... 5-4 5.3 Dissassembly ... 5-5 5.3.1 Knobs ... 5-5 5.3.2 Cabinet Removal ... 5-5 5.3.3 C-Box Removal ... 5-5 5.3.4 The G Box ... 5-7 5.4 . Recalibration and Adjustments ... 5-7 5.4.1 Internal Capacitance Standards ... 5-8 5.4.2 Conductance Multipliers .. . 5-8 5.4.3 C301/Setting Zero C ... 5-8 5.4.4 Lever-Switch Stiffness ... 5-8 5.4.5 Maintenance Note On Switches ... 5-8 5.5 Trouble Analysis ... 5-9 5.5.1 Mechanical Damage ... 5-9 5.5.2 BCD Circuits ... 5-9 5.5.3 Non-Repairable Subassemblies ... 5-9 5.5.4 Typical Parameters ... 5-9 5.6 Parts Lists and Diagrams ... 5-9

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