Capacitance Standards

Capacitance Standards

 

standard (electrical) capacitors, characterized by highly stable nominal capacitance (constant calibration). Such standards are used mainly for accurate measurements conducted with capacitance meters and q-meters. Capacitance standards are divided into two groups: (1) constant capacitance of 0.5 pF (picofarad) to 0.1μF and (2) variable capacitance of up to 0.002 μF. The dielectric in the standards is usually a high-grade mica, a ceramic with low dielectric losses, and air. The temperature coefficient is usually 10-5-10-6 deg-1 and the loss tangent is tan δ = 10-3-10-4. Measures of capacitance are carefully shielded during accurate measurement in order to reduce any capacitive coupling with surrounding objects.

REFERENCE

Valitov, R. A., and V. N. Sretenskii. Radiotekhnicheskie izmereniia. Moscow, 1970.
References in periodicals archive ?
NIST plans to transfer the frequency dependence data to the Farad Bank and other reference capacitance standards, so that in the near future, improved capacitance calibrations will be available from NIST for the entire audio frequency range.
This compares favorably with the total relative uncertainty of 4X 10 (-8), which is achieved for the highly optimized comparisons against the calculable capacitor that are performed as part of the regular maintenance of NIST's primary bank of capacitance standards.
Recent work at NIST has resulted in a factor of three decrease in the uncertainty for certain of the highest-level calibrations of fused-silica capacitance standards.