Transformer & Switchgear
Off-line Testing

Digital Resistance Meter - Model DRM-100™
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The DRM-100 instrument can precisely measure contact resistance on circuit breakers, switches, bus bar joints and other lowresistance devices in a high voltage environment.

Digital Resistance Meter Instrument Features
  • Precise contact resistance measurement
  • True DC current is automatically ramped up and down
  • Test cycle programmable from 10-60 seconds
  • Large, bright, high resolution, color screen
  • Continuous mode for trouble shooting
  • High accuracy and resolution
  • Emergency OFF button and auxiliary grounding terminal for safety
  • High strength and waterproof Instrument case for rough field use
  • Test leads and accessories in separate carrying case
  • Also available with internal memory, printer, USB port. Model DRR-100
  • Color screen
  • Auto ranging

Up to 100 Amps of pure DC current is smoothly ramped up and down automatically to prevent current transients that can lead to unwanted operation of protection relays. Output current is preset by operator to a value between 10-100 Amps and is maintained for a preset time period between 10-60 seconds.

A 20-Amp continuous mode is also provided to aid in trouble shooting by allowing the operator to move and
relocate the potential leads during testing.

The DRM Instrument is specifically designed for rough usage and to function reliably in energized EHV substations where high electrical and magnetic fields are frequently present.

The DRM Instrument was also designed to function accurately and reliably with up to 1000 VAC of noise present on the device under test - a common condition in energized transformer stations.

Test results are displayed in extra large font on the bright color LCD screen.

Membrane switch buttons surround the screen for setting the test current, test time and for initiating the test.

The DRM uses the 4-terminal method of resistance measurement to eliminate the effects of lead resistance.