Ring electrode measuring method

Ring electrode measurement method: Precise resistance measurement of insulators and semiconductors

The Determination of high electrical resistances This places special demands on measurement technology and methodology. Particularly with insulators and semiconductors in the upper resistance range (from approx. 10⁴ Ω·cm), the Measurement with concentric ring electrodes established as a reliable procedure.

This method enables a defined current flow and forms the basis for reproducible and standard-compliant measurement results – especially in materials testing and quality assurance.

Operating principle of ring electrodes

Measuring heads with concentric ring electrodes They consist of an inner and an outer electrode. An electric field is created between these electrodes, through which the current is directed across the sample surface or through the material.

Ring electrode measurement with measuring head — Ring electrode measurement measuring heads

This defined geometry allows the current distribution to be described precisely – a crucial prerequisite for calculating the specific resistance.

Constant voltage method at high resistances

For very high resistance values (typically Rx > 20 MΩ), the constant voltage method is used.

Since the currents involved are extremely low, increased test voltages of up to 1000 V are used. This enables stable measurement conditions and improves signal evaluation without distorting the material properties.

Guard technology for stable measurement results

A major problem when measuring high resistances is interference from leakage currents or environmental conditions. To reduce these effects, the so-called [missing term] is used. Guard technology for use. An additional connection is used, which is at ground potential and creates a defined reference system.

This technique ensures that unwanted currents are specifically diverted without affecting the actual measurement – a crucial factor for precise results in the high-resistance range.

Influence of electrode geometry

The Geometry of the ring electrodes has a direct influence on the measurement result. Therefore, Correction factors used, which depend solely on the dimensions of the measuring head used.

Modern measurement systems like the Hiresta-UX incorporate these correction factors. automatically for the respective measuring headsWhen selecting the appropriate measuring head, the corresponding factor is taken into account directly, which simplifies the application and reduces sources of error.

These factors enable the conversion of the measured resistance to the specific resistance and ensure that measurement results remain comparable.

Measuring head	d2 (cm)	d1 (cm)	RCFs	RCFv
UR-SS	0.6	0.3	9.065	0.071
URS	1.1	0.59	10.09	0.273
UR	3.0	1.6	10.00	2.011
UR-100	5.32	5.0	100	19.63
UA	-	-	1.050	-
U-Type JBox	7.0	5.0	18.85	19.63

Measuring instruments for the ring electrode method

Conductivity meter for material testing in the laboratory — Use in development and quality assurance

Specialized high-resistance measuring devices are used for the practical implementation of this measurement method. A typical example is the Hiresta UXthat for the Measurement of surface and volume resistances is designed for high-resistance applications.

The system works with corresponding Ring electrode measuring heads and supports both the constant voltage method and the guard technique, enabling precise and standard-compliant measurement results.

Relationship between resistance and specific resistance

The calculation of the specific resistance is based on the current density between the concentric electrodes.

By defining the current distribution, both the surface current density and the electric field within the measurement area can be determined. This results in an exact description of the material behavior – independent of the specific sample shape.

Typical areas of application

The ring electrode measurement method is used in various industries, especially when high resistances and reliable material characterization are required: