Accuracy is defined as the difference between the measured value or reading and the true or accepted value. This is also referred to as the absolute accuracy. There is also a relative accuracy which reflects the difference between the measured value and a secondary reference standard. The secondary reference standard can typically be traced to an absolute standard or value through what is called a calibration chain.

Avoiding Errors
Avoiding measurement errors page discusses common errors and techniques to reduce errors.
Avoiding Errors Link


Abbreviated as C (as in LCR). A capacitor is a passive component comprised of two conductors separated by a dielectric. A capacitor stores charge, blocks DC flow and allows AC flow based on frequency and capacitor design.

The ratio of charge on either plate of a capacitor to the potential difference (voltage) across the plates. When a voltage is applied, current flows immediately at a high rate and then decays exponentially toward zero as the charge builds up. If an AC voltage is applied, an AC current appears to flow continuously because the polarity of the voltage is reversed at the frequency of the applied voltage. The waveform of this current is displaced in time from the applied voltage by 90°.
Seen in: Capacitance Measurement, Capacitance Meter

Related to “Capacitance”: Capacitance Standards LCR Meter


Charging Current
An insulated product exhibits the basic characteristics of a capacitor. Application of a voltage across the insulation causes a current to flow as the capacitor charges. This current instantaneously rises to a high value as voltage is applied then exponentially decays to zero as the DUT becomes fully charged. Charging current decays to zero much faster than dielectric absorption.

Related to “Charging Current”: Megohmmeters

Direct current, non-reversing polarity. The movement of charge in one direction, such as that from a battery. Describes both current and voltage.

Related to “DC”: Precision Voltage and Current Source

Dielectric Absorption
The physical aspect where insulation appears to absorb and retain an electrical charge slowly over time. Apply a voltage to a capacitor for an extended period of time and then quickly discharge it to zero voltage. Leave the capacitor open circuited for a period of time then connect a voltmeter to it and measure the residual voltage. The residual voltage is caused by the dielectric absorption of the capacitor.

ESR equivalent series resistance
ESR stands for equivalent series resistance, the same quantity that is also called Rs. A single resistive value of a capacitor representing all real losses. These losses in a capacitor are: dielectric loss, leakage resistance, and loss in actual series resistance. ESR is typically much larger than the series resistance of leads and contacts of the component, especially at higher frequencies.
ESR is a measure of the loss in a capacitor and is related to D by: ESR = Rs = D/ ωC where ω =2πf.

An acronym for Institute of Electrical and Electronic Engineers, a professional association of engineers.

IEEE 488
General Purpose Interface Bus (GPIB) - an industry standard definition of a parallel bus connection for the purpose of communicating data between devices.

A term used with alternating current circuits to describe the "ac resistance" to the flow of current through a circuit when an ac voltage is applied across the terminals of that circuit. Impedance is a complex quantity composed of real (in phase with voltage) and reactive (out of phase by 90°) components. Impedance is calculated as voltage divided by current. Impedance is the sum of alternating current oppositions (capacitive reactance, inductive reactance and resistance).
Z = R + jX


Seen in: Impedance Meter
Related to “Impedance”: LCR Meter

Abbreviated L (as in LCR). An inductor is a coil of wire. It is used to create electromagnetic induction in a circuit.

The property of a coil to oppose any change in current through it. If the turns (coils) of the wire are stretched out, the field intensity will be less and the inductance will be less. Unit of measure is the Henry (H).

Related to “Inductance”: LCR Meter

Inductance Meter
An inductance meter measures inductance or "L" as in LCR. LCR meters are sometimes referred to as inductance meters for their ability to perform inductance testing.

Related to "Inductance Meter": LCR Meter

Inductive Reactance
A measure of how much the counter electro-magnetic force (emf) of the coil will oppose current variation through the coil.

The protection against flow of current, as between a circuit of a product and the ground reference. Materials that prevent current flow are referred to as insulators or dielectrics.

Related to "Insulation": Megohmmeters

Insulation Resistance
Characteristic of an insulating material that being subject to voltage, indicates a resistance such that the value of leakage current which flows through it stays within acceptable limits.

Insulation Resistance Tester
An insulation resistance tester measures a component’s insulation and gives a whole, quantifiable value. An insulation resistance tester uses direct current or DC.

Related to "Insulation Resistance Tester": Insulation, Insulation Resistance

LCR Meter
A LCR meter, Inductance (L), Capacitance (C), and Resistance (R), is a piece of electronic test equipment used to measure the impedance (inductance, capacitance, resistance) of a component.
*See LCR Meters from IET Labs

The resistance ranges the test instrument uses for reference in making the measurement.

Reactive Component
The component of an AC voltage, current, or impedance that is 90° out of phase with the "real" or in phase component. Reactive components are associated with capacitive or inductive circuits.

Real Component
The component of a voltage, current, or impedance that is in phase with the "real" component. Real components are associated with purely resistive circuits.

The difference between successive measurements with no changes in the test setup or test conditions.

Similar to repeatability but adds the element of what could be expected under real life conditions. Reproducibility would take into account the variability in things like fixtures, where the DUT being tested is removed from the fixture and re-inserted.

The smallest value that can be shown on the display in a digital instrument. LCR meters typically specify a measurement range that is the largest and smallest value that can be shown on that meter’s display. The smallest increment on an analog meter

Resistance (R)
The electrical characteristic that impedes the flow of current through a circuit to which voltage has been applied. Resistance is calculated by Ohm's Law as voltage divided by current (for DC circuits). For AC circuits, it is the in-phase or "real" component of impedance. Units are expressed in ohms (Ω).

RS232 An industry standard definition for a serial line communication link or port.

The AC output voltage of most LCR meters can be programmed to select the signal level applied to the DUT. AC voltages are RMS values. Generally, the programmed level is obtained under an open circuit condition. A source resistance (Rs, internal to the meter) is effectively connected in series with the ac output and there is a voltage drop across this resistor. When a test device is connected, the voltage applied to the device depends on the value of the source resistor (Rs) and the impedance value of the device. Some LCR meters do have voltage leveling which keeps the output voltage at the programmed value as the impedance of the DUT varies.