10-kV High-Accuracy DC Voltage Divider

A high-accuracy voltage divider based on the Hamon/Rayleigh ratio principle has been made for the absolute measurement of the volt and also for building up the voltage scale to 10 kV. It is composed of 100 equal resistors of nominal value 100 k? and an adjustable 100-k? resistor with taps at 10 and 1 k?. By using appropriate connections, a total 10-M? divider with 1-k? output is constituted in which various voltage ratios up to 104 can be obtained. A guard circuit is provided to minimize the leakage currents. The calibration of the divider is simplified by using parallel or series-parallel connection of resistance elements so that all comparisons are made at a ratio of 1:1. For 10 kV only, two comparisons are required. The measurement of performance of the divider and the analysis of errors have been made. The most important factor affecting the voltage ratio is self heating, for which a correction is necessary. The total error would be less than 0.58 ppm.     

An Optimized Design for a Low-Frequency Inductive Voltage Divider

A theoretical investigation of the causes of error in multidecade two-staged inductive voltage dividers (IVD) has been made and from this an optimized design for the frequency band 10-400 Hz has been evaluated. A three-decade divider rated at 0.6 times frequency has been constructed and calibrated and the errors of voltage division do not exceed the design limits of 5 × 10-9 of input.     

直流电阻分压器的非线性机理研究

针对电阻分压器在直流低电压分压时出现的非线性现象,采用独立影响因素的分析方法,对直流电阻分压器的非线性机理进行了研究.通过分析和实验验证,确定了造成非线性的原因是工作电流的变化导致电阻分压器输出热电势的变化.据此,建立了非线性数学模型,提出了非线性修正方法.利用该方法,±200μV直流电压输出非线性误差小于5 nV.     

Simple Divider Yields Low-Frequency Calibration Pulses

A single-stage pulse-frequency divider is presented which operates on 60 Hz to yield low-frequency pulses. The divider exhibits unusual stability against disrupting influences and the resulting pulses have exceptional timing accuracy. For example, the 1-second pulses (division by 60) are reliable over an ambient temperature range of from -40 to + 80°C. Division by 300, yielding pulses at 5-second intervals, is reliable from + 5 to + 45°C. Timing accuracy of the pulses is equal to the average line-frequency accuracy-typically ±0.02 percent.     

10-kY 10-mA DC Supply with 0.1-ppm Stability

A 10-kV stabilized supply with a dc capacity of 10 mA has been constructed. Its drift rate measured over time intervals greater than about 1 minute and extending to times of more than 10 hours is about 1 part in 107 per hour. For shorter times from 1 second to 1 minute the peak-to-peak deviation from the mean is about 2 mV at 9.2 kV or ±1 part in 107. This performance has been achieved by the use of an initially well regulated commercial 10-kV supply in a closed-loop control system. High dc loop gain has been achieved by the use of a chopper-stabilized amplifier, and a guarded resistive divider of special design. The reference voltage is made up of a bank of unsaturated standard cells enclosed in a temperature-controlled air bath whose short term temperature stability is ±0.001°C. The control resistive divider, together with a measuring divider and a guard divider, are enclosed in an oil bath whose temperature is controlled near ambient to within ±0.01°C.     

Flexible and transparent electrothermal film heaters based on graphene materials

High-performance and novel graphene-based electrothermal films are fabricated through a simple yet versatile solution process. Their electrothermal performances are studied in terms of applied voltage, heating rate, and input power density. The electrothermal films annealed at high temperature show high transmittance and display good heating performance. For example, the graphene-based film annealed at 800 °C, which shows transmittance of over 80% at 550 nm, can reach a saturated temperature of up to 42 °C when 60 V is applied for 2 min. Graphene-based films annealed at 900 and 1000 °C can exhibit high steady-state temperatures of 150 and 206 °C under an applied voltage of 60 V with a maximum heating rate of over 7 °C s(-1) . For flexible heating films patterned on polyimide, a steady-state temperature of 72 °C could be reached in less than 10 s with a maximum heating rate exceeding 16 °C s(-1) at 60 V. These excellent results, combined with the high chemical stability and mechanical flexibility of graphene, indicate that graphene-based electrothermal elements hold great promise for many practical applications, such as defrosting and antifogging devices.     

Optimization of the internal admittance load of an inductivevoltage divider for low ratio error

The distributed capacitances between the strands of an inductive voltage divider degrade the voltage ratio. A calculation scheme to convert the distributed capacitances into equivalent concentrated capacitances at the taps is given. An optimized connection scheme for the strands is calculated to produce concentrated capacitances which are as equal and as small as possible. Capacitors are added at the taps for optimum equalization. The relative error of the output voltage for a 120-V:10-V divider has been reduced to less than 1×10^-7 in phase and less than 1 μrad in quadrature, at a frequency of 50 Hz     

Multistable bridge element for pulse counters

Conclusions The above circuit can be used as a multistable pulse-position storage element in designing decimal counting decades for digital and computer devices, and also a frequency divider with a large ratio from 2 to 100.By utilizing the stabilizing properties of the bridge circuit, the scaling factor is maintained at a constant value in the temperature range of –20 to + 60°C with supply voltage variations of ±2% and replacement of circuit components.Bearing in mind the advantages and simplicity of this circuit it is advisable to organize mass production of such elements with integrated microcircuits.Translated from Izmeritel'naya Tekhnika, No. 10, pp. 41–43, October, 1973.     

Coaxial Capacitive Dividers for High-Voltage Pulse Measurements in Intense Electron Beam Accelerator With Water Pulse-Forming Line

In this paper, a new coaxial capacitive divider is investigated. The electrical characteristics of the capacitive divider are theoretically analyzed, and the parameters of the capacitive divider are calculated and measured. Its rise time is about 8 ns, and the divider ratio is over 2000. The divider is employed to measure the pulsed high voltages of an intense electron beam accelerator with a water pulse-forming line (PFL) in our laboratory. The capacitive divider can directly measure the diode voltage within nanoseconds, and when combined with an integrator, it can measure the PFL charging voltage with a duration of several microseconds. Compared with conventional resistance dividers, the capacitive divider has more advantages, such as compactness, stability, a relatively high divider ratio, a fast response time, and not much of an effect on the accelerator.      

Low blank isotope ratio measurements of rhenium, osmium, and platinum using tantalum filaments with negative thermal ionization mass spectrometry

Platinum is most commonly used as a filament for Re and Os isotopic measurements, but it contains impurities of Re and Os. Tantalum is low in platinum group elements (PGE) and in Re, but it is not used for negative thermal ionization mass spectrometry because of high electron emission and high reactivity with O(2). High thermal electron emission from Ta distorts the preoptimized ion source optics. In addition, Ta consumes O(2), leaving little for samples, but O(2) is essential for isotopic ratio measurements of PGE and Re as they are measured as negatively charged oxides, such as OsO(3)(-) and PtO(2)(-). These problems are solved by prebaking a filament to remove tantalum oxides before sample loading, keeping relatively high filament temperatures and high O(2) pressures (P(O)((2))) during the sample run, and lowering the potential difference between the filament and the draw-out plate. At P(O)((2)) of ～1 × 10(-)(5) Torr in the source, strong (>10 V) stable (>6 h) peaks of ReO(4)(-), OsO(3)(-), and PtO(2)(-) are obtained at 750 °C for Re, 850 °C for Pt, and over 900 °C for Os. Accurate isotopic ratio measurements of Re, Os, and Pt at picogram levels are possible using Ta filaments.     

Frequency Stabilization of Ar+ Lasers by Saturated Absorption in External 127I2 Cells (at 582 THz)

The frequency of commercial Ar+ lasers at 582 THz was stabilized by an external device mainly consisting of a 127I2 cell, two photodetectors, an electronic divider, and a conventional servo loop, using the 3f locking technique. The symmetry of the 3f signals was tested by two methods. In the neighborhood of the central zero crossing at separations of up to ±300 kHz no asymmetry could be detected within 4 × 10-13 v. The stabilized frequency?being independent of the modulation width?is reproducible to better than ±2 × 10-11 v. From the small dependence of the frequency on the I2 vapor pressure of -5 kHz/Pa an uncertainty of less than ±4 × 10-11 v is assumed. Thus the selected 127I2 lines at v = 582 THz/? = 515 nm should be promising candidates as optical frequency or wavelength standards.     

Efficient driving-capability programmable frequency divider with a wide division ratio range

A programmable frequency divider with close-to-50% output duty-cycle, with a wide division ratio range, is presented. The proposed divider has also provisions for binary division ratio controls, and has demonstrated operation at frequencies as high as 3.5 GHz. With the above features, the proposed divider can be used in phase-locked loops, and is capable of driving various clocked circuits, which need different clock frequencies. The proposed divider has division ratios from 8 to 510, but it can easily be extended to higher ranges by simply adding more divider stages. The divider circuit has been realised in a 0.18-mum RF CMOS process. Test results show that the output duty-cycle is 50% when the division ratio is an even number. For odd division ratios the worst-case duty-cycle is 44.4% when the division ratio is 9. The output duty-cycle becomes closer to 50% when the division ratio is an increasing odd number. For each division ratio, the output duty-cycle remains constant for different chips, with different input frequencies from gigahertz down to kilohertz ranges, and with different power supply voltages.     

Isolated-Section Inductive Divider and Its Self-Calibration

A high-precision isolated-section inductive divider, designed for self-calibration, has been developed. In this new design principle, the two major sources of ratio error, excitation current and current through stray capacitance between sections of divider windings, have been greatly reduced by the use of a separate excitation winding and a guard for the divider winding. In a self-calibration divider ten divider winding sections are electrostatically isolated from each other by their guards. The divider can be calibrated by internal exchange of the winding sections and comparison with an auxiliary divider having a fixed nominal ratio of 0.1, similar to the calibration of a resistive divider. The design principle is also applied to another divider in which a second winding is added. This divider can be used for a high-precision multidecade divider and for the calibration of other ininductive dividers using a "boot-strapping" method. Construction details of the dividers, sources of errors, results of self-calibration, and evaluation of uncertainties are presented. The uncertainties of the self-calibration are estimated to be ±3 X 10-9 of the input at 100 Hz to 1 kHZ, and ±30 X 10-9 at 10 kHz.     

Optical, thermo-optic, electro-optic, and photoelastic properties of bismuth germanate (Bi(4)Ge(3)O(12))

To assess the suitability of bismuth germanate as an electro-optic material for high precision applications, we have confirmed and extended previous data on its refractive index, electro-optic tensor element r(41), and thermal expansion coefficient. In addition, we have measured the thermo-optic coefficient dn/dT, the temperature dependence of the electro-optic coefficient, and the stress-optic tensor elements. From the stress-optic tensor elements and previously published data, we have computed the strain-optic tensor elements. The index of refraction is given, to a good approximation, by the single-term Sellmeier equation, n(2) - 1 = S(0)λ(0)(2)/[1 - (λ(0)/λ)(2)], with S(0) = 95.608 μm(-2) and λ(0) = 0.1807 μm. The thermo-optic coefficient is 3.9 × 10(-5)/°C at 632.8 nm and 3.5 × 10(-5)/°C at 1152.3 nm. The electro-optic tensor element varies between approximately 1.05 and 1.11 pm/V over the spectral range of 550-1000 nm; its normalized effective change with temperature is approximately 1.54 × 10(-4)/°C. The thermal expansion coefficient is 6.3 × 10(-6)/°C over the range 15-125 °C. Values of the stress-optic tensor elements are q(11) - q(12) = -2.995 × 10(-13) m(2)/N and q(44) = -0.1365 × 10(-12) m(2)/N. The strain-optic tensor elements are p(11) - p(12) = -0.0266 and p(44) = -0.0595.     

Calculating precision voltage dividers

Conclusions In adjustable voltage dividers the resistance of the jumpers and the insulation resistance between the contacts of the switches in the jumper circuits cause a positive systematic error of the division factor.The effect of the resistance of the jumpers increases as the resistance of the sections of the transformed portion of the voltage divider decreases, which is one of the causes which limit the reduction of the voltage-divider resistance. The effect of the insulation resistance between switch contacts in the jumper circuits increases as the resistance of the sections of the transformed part of the voltage divider increases. This latter factor is one of the causes limiting the increase in the resistance of the voltage divider.These conclusions apply equally to measurement of a ratio of resistances under conditions in which the method of series-parallel transformation is used.Translated from Izmeritel'naya Tekhnika, No. 6, pp. 62–63, June, 1971.     

Common error sources in using a series-resistors-type voltagedivider below the level of 0.01 ppm

A series-resistors-type voltage divider is one of the most commonly used dividers. We have carefully analyzed various error sources such as leakage current, normal mode rejection ratio of the voltmeter, temperature coefficient, and others. The KRISS' 10:1 divider which was used for 10-V calibration was chosen for this study. Here, we would like to describe some common error sources and their effects which should be taken into account in the level of 10^-8 or below for the series-resistors type voltage dividers     

高准确度直流电阻分压箱的校准

分析了直流电阻分压箱的技术指标和校准水平，提出了等分测量的校准方法，进行了不确定度分析，给出了验证方法。结果表明：用该方法校准的分压箱，比率误差为１０＾－７量级。     

A 1-MHz Binary Inductive Voltage Divider with Ratios 2n to 1 or 6n dB

A voltage divider with ratios of 2n to I or 6n dB is obtained by cascading n binary dividers, each having a voltage ratio of 2 to 1. A theoretical analysis results in an expression for the ratio error. Several techniques are given for reducing this error. A voltage comparator is described for eliminating errors due to external loading of the divider. An experimental cascaded binary divider with a total of 42 dB in seven 6-dB steps is described. The attenuation of the divider was measured with a precision waveguide-below-cutoff attenuator at 1 MHz. The divider and attenuator values agree within the uncertainty of the attenuator and measuring system at 1 MHz.     

Comparative High Voltage Impulse Measurement

A facility has been developed for the determination of the ratio of pulse high voltage dividers over the range from 10 kV to 300 kV using comparative techniques with Kerr electro-optic voltage measurement systems and reference resistive voltage dividers. Pulse voltage ratios of test dividers can be determined with relative expanded uncertainties of 0.4 % (coverage factor k = 2 and thus a two standard deviation estimate) or less using the complementary resistive divider/Kerr cell reference systems. This paper describes the facility and specialized procedures used at NIST for the determination of test voltage divider ratios through comparative techniques. The error sources and special considerations in the construction and use of reference voltage dividers to minimize errors are discussed, and estimates of the measurement uncertainties are presented.     

Pulsewidth Modulation DC Potentiometer

This instrument uses pulsewidth modulation techniques in which a crystal oscillator, frequency divider, and preset counter replace the resistive divider to form a precision potentiometer. The smoothing of the time-division intervals to a steady-state direct current without introducing prohibitive time constants is solved by a "sectional average" integrating circuit. This utilizes a short time-constant integrator combined with a switched unity-gain buffer amplifier in the feedback to integrator input. This switch, integrate, and sample-and-hold circuit provides output within ±0.1 percent of the eventual steady-state value in less than 400 ms after a step change and within ±0.001 percent in 600 ms. The system provides digital compatibility with tape, cards, digital voltmeters, etc. An engineering prototype has 7 decade dials covering a 0-100.0000-volt range with ±(0.1 ppm + 5?V) voltage-ratio accuracy and, ±0.05 ppm/50°C temperature coefficient and ±0.05 ppm/ 10-week long-term stability, and it is expected that this may be improved.