The MMR-630 Series meters are professional portable instruments for measuring very low resistances. Due to their special measurement algorithm they can be used for both resistive and inductive type of a specimen that makes

MMR-630 series perfect instruments for electricians testing electrical junctions, motors and power transformers windings. The results can be stored in the internal memory and send to a computer via serial interface. A quick PASS/FAIL test function with results displayed and acoustically indicated simplifies measurements considerably.

  • Measurement of resistive object type:
    • welded and soldered connections, equipotential bonding, earth wire,
    • terminals and connectors, rail welded joints, cables and wires,
    • measurement 4-pole method.
  • Measurement of inductive object type:
    • coils (motors and transformers), low resistance coils.
  • Range selection autoranging or manual (measurement of inductive object type).
  • Selectable measurement mode adjusted to object type:
    • for resistive objects - fast mode (3 seconds),
    • for inductive objects - long mode with automatic discharge after measurements (or with lower accuracy - shorter mode).
  • Selectable measurement mode adjusted to application:
    • normal mode - after pushing „START” button,
    • automatic mode - since test leads are connected to the object meters automatically starts measurement with dual direction current flow and gives average result - what eliminates eventual DC voltage on tested object,
    • continuous mode - every 3 seconds for resistive objects or continuous measurement for inductive objects.
  • Window mode:
    • this option enables setting an upper and a lower limit between which the average measurement result is bound to appear. The results outside of this range will be indicated by two long audible signals and the symbols.
  • MMR-630 is designated not to be effected by interference up to 20 mV and to show noises from 20 to 100 mV (so in edge conditions even 5 times higher than measured drop of potential).
  • Memory store for up to 990 results and a communications facility for transferring data from the device to a PC.

Electric security:

  • type of insulation: double, according to EN 61010 - 1 and IEC 61557
  • measurement category: CAT III 300 V acc. to EN 61010 - 1
  • protection class acc. to EN 60529: IP54

Other technical data:

  • meter’s power supply: battery package SONEL/Ni-MH 4,8 V
  • battery charging time: approx. 2,5 hours
  • number of measurements with the current of 10 A: 300
  • auto-off time: 120 seconds
  • immunity to interference: additional error ≤1% for voltage 50 Hz ≤100 mV RMS
  • maximum leads resistance for the 10 A current: 0,1 Ω
  • maximum inductance of the tested object: 40H
  • accuracy of the test current: ±10%
  • resistance measurement time:
    • with the selected resistive object type with the bidirectional current: 3 seconds
    • with the selected inductive object type, dependant on the resistance
    • and inductance of the object: a few minutes (max. 10)
  • dimensions: 295 x 222 x 95 mm
  • weight: approx. 1,7 kg

Rated operational conditions:

  • operation temperature: 0...+40°C
  • storage temperature: -20...+60°C

MMR-620 microohmmeter conforms the following directives or standards according to CE requirements.

Low Voltage Directive (LVD) 73/23/EEC, 93/68/EEC.

EN 61010 - 1:2001 Safety requirements for electrical equipment for measurement, control and laboratory use. General requirements . 
EN 61010 - 031:2002: Safety requirements for electrical equipment for measurement, control and laboratory use. Safety requirements for hand-held probe assemblies for electrical measurement and test.

Electromagnetic compatibility (EMC) 89/336/EEC, 92/31/EEC, 93/68/EEC.

EN 61326:1997+A1:1998+A2:2001 Electrical equipment for measurement, control and laboratory use - EMC requirements.

Resistance measurement

MMR-630 Current Accuracy
Range Resolution
0...999,9μΩ 0,1μΩ 10 A ±(0,25% m.v. + 2 digits)
1,0000...1,9999 mΩ 0,0001 mΩ
2,000...19,999 mΩ 0,001 mΩ
20,00...199,99 mΩ 0,01 mΩ 1 A
200,0...999,9 mΩ 0,1 mΩ 0,1 A
1,0000...1,9999 Ω 0,0001 Ω
2,000...19,999 Ω 0,001 Ω 10 mA
20,00...199,99 Ω 0,01 Ω 0,1 mA
200,0...1999,9 Ω 0,1 Ω 0,1 mA

- input impedance of the voltmeter: ≥200 kΩ

„m.v.” - measured value.

Complete device information
Manufacturer site:


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Sonel MMR-630 Micro-ohmmeter

  • Brand: Sonel S.A.
  • Model: MMR-630
  • Product Number: WMGBMMR630
  • Availability: 2 to 14 days order processing
  • 0.00€

Tags: Sonel, MMR-630, Micro-ohmmeter