The MMR-620 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-620 a perfect instrument for electricianstesting 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. The MMR-620 meter can also be used for testing the quality of the junctions in a production process via the interface.

• 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.

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

Resistance measurement

- input impedance of the voltmeter: ≥200 kΩ

„m.v.” - measured value.