OM 22 benchtop micro-ohmmeter is used for 4-wire measurement of very low resistance values up to 20 KΩ with an accuracy of 0.03% RDG and a 0.1 µΩ resolution. Programmable, it is particularly suited for use on test benches with repetitive measurement tasks. The reliability and accuracy of the measurements is improved by a low temperature coefficient of 10 ppm/°C, automatic removal of EMF parasites before each measurement, metal temperature compensation and compensation of ambient temperature.

With three current waveforms available -continuous, pulse or AC current- from 100 µA to 10 A and high flexibility of trigger and sampling conditions, OM 22 low resistance ohmmeter covers a wide range of applications: Cable resistance and resistivity measurement, inductive resistance measurement (motors and transformers winding resistance),contact resistance measurement (connectors, switches, relays…),test of low power electrical components (fuses…) and heat sensitive devices, metallisation / earth bonding and ground continuity measurement.

OM 22 is a programmable instrument, ideal for use on test benches: it has 6 configurations to be modified and recalled by users upon request through the 6 direct keys on the front board. Every configuration defines every measurement aspects: range, current waveform and value, number of measurements per cycle with temporisation, storage conditions, temperature compensation, measuring unit, metal under test, calculations of coil heating or W/km, alarm settings, maximum measurement voltage, analogue output, trigger conditions.

If necessary, OM 22 configurations can be modified through LOG OM data management software delivered in the standard package.

Up to 1,000 samples can be stored inside the instrument and be recalled directly on the display or on computer via LOG OM.

Powered from mains or from rechargeable batteries in option, the electronic calibration of the instrument is performed without any internal adjustment.

Resistance measurement
Range Resolution Accuracy at 90 days(23°C ±1°C) Measuring current Voltage drop
2 mΩ 0.1 μΩ 0.05% + 0.3 μΩ 10 A 20 mV
20 mΩ 1 μΩ 0.05% + 2 μΩ 10 A 200 mV
20 mΩ 1 μΩ 0.05% + 3 μΩ 1 A 20 mV
200 mΩ 10 μΩ 0.05% + 10 μΩ 10 A 2 V
200 mΩ 10 μΩ 0.05% + 20 μΩ 1 A 200 mV
200 mΩ 10 μΩ 0.05% + 30 μΩ 100 mA 20 mV
2 Ω 100 μΩ 0.05% + 100 μΩ 1 A 2 V
2 Ω 100 μΩ 0.03% + 200 μΩ 100 mA 200 mV
2 Ω 100 μΩ 0.03% + 300 μΩ 10 mA 20 mV
20 Ω 1 mΩ 0.03% + 1 mΩ 100 mA 2 V
20 Ω 1 mΩ 0.03% + 2 mΩ 10 mA 200 mV
20 Ω 1 mΩ 0.03% + 3 mΩ 1 mA 20 mV
200 Ω 10 mΩ 0.03% + 10 mΩ 10 mA 2 V
200 Ω 10 mΩ 0.03% + 20 mΩ 1 mA 200 mV
200 Ω 10 mΩ 0.03% + 30 mΩ 100 µA 20 mV
2 kΩ 100 mΩ 0.03% + 100 mΩ 1 mA 2 V
2 kΩ 100 mΩ 0.03% + 200 mΩ 100 µA 200 mV
20 kΩ 1 Ω 0.03% + 1 Ω 100 µA 2 V


Further features
Configurations 6 configurations available, to be modified if necessary with LOG OM software delivered in standard
Resistance types Inductive resistances: Coils, transformers, motor windings...Non-inductive resistances: Earth bonding, coating, contact resistances...
Measuring current Internal or external sourceDC current from 100 µA to 10 AContinuous, pulsed or pulsed alternated
Measurement time < 1 s in direct current mode< 1,5 s in pulse current mode< 2 s in alternate current mode
Measurement trigger conditions Manual or automatic trigger from 2 measures/s to 1 measure/9h, allowing a single operator to be able to perform measurements
EMFs Automatic compensation of EMF parasites before each measurement for a greater accuracy
Temperature compensation Choice of metal temperature coefficientChoice of ambient temperature (programmed or measured with external probe)Temperature compensation at 20°C: Resolution: 0.1°C, accuracy: ±0.5°C(R20 = Resistance compensated at ambient temperature equal to 20°C
Temperature coefficient beyond operating range < 10% accuracy/°C
Relative measurements Display L = R-R0 or L = 100 x (R-R0)/R0 in %Where L: read value, R: measured value and R: reference value either recalled from memory or entered by the operator
Coil heating calculation Coil heating calculation according to ambient temperature, original coil resistance at ambient temperature, coil resistance once heated and coil material
Alarms 2 programmable thresholds with visual and sound signal and relay outputs
Outputs Two relays (1 A / 220 VAC)1 analogue output 0 – 2.5 V (load >= 2.5 kΩ, resolution: 10 mV, accuracy: ±10 mV)
Calibration Digital calibration without internal adjustment


General specifications
Size 225 x 88 x 310 mm
Weight 2 to 3 kg depending on options
Display LCD 26,000 counts, 16 figures lighted, 11.5 mm high
Power supply 115 / 230 V (50 / 60 Hz)
Battery with internal charger(option) Type: 12 V battery packBattery life: 2 to 8 h according to useCharging time: 14 h
Communication ports RS 232 in standardIEEE 488-2 in optionAllows programming, data management and unit calibration directly from a computer
Storage capacity 1,000 measurements with average, minimum and maximum valueMemory reading directly on the display or through digital and analogue interfaces


Environmental specifications
Reference range 23°C ±1°C (RH: 45 to 75% w/o condensing)
Operating reference range 0 to 50°C (RH: 20 to 80% w/o condensing)
Limit operating range -10°C to +50°C (RH: 10 to 80% w/o condensing)
Storage temperature limits -30°C to +55°C(-15°C to +50°C for model with battery)
Protection IP IP40 according to EN60529
Maximum altitude 2,500 m


Safety specifications
Protections Electronic protection for ‘voltage’ wiresFuse protection for ‘current’ wiresProtection against ‘current’ circuit breaking during inductive resistance measurements
Class In accordance with EN 61010-1Category III, pollution 2
Rated voltage 50 V
Chocks and vibrations EN61010-1
EMC conformity Immunity:EN 50082-1/1992Conducted and radiated emissions:EN 55022, class BRadiated: IEC 801-3/1984Conducted: IEC 801-4/1988Electrostatic discharges: IEC 801-2/1991