Specifications for the Vanguard Auto-Ohm 100 Ampere Micro-Ohmmeter

Vanguard_Auto-Ohm100The Vanguard Auto-Ohm 100 Ampere Micro-Ohmmeter applies a true DC current from 10A to 100A to the resistance load to be tested. Any test current setting can be selected by using the function control knob on the front panel.

The Vanguard Auto-Ohm 100 Ampere Micro-Ohmmeter controls the test current’s rise and fall rates by using a switching DC power supply and a current regulator circuit.

The Auto Test Mode feature can be initiated simply by applying the sensor cables’ leads across the two points of interest, making the measurement of a sequence of several resistance values in a breaker contact very convenient.

Since a true DC ramped current is passed through the breaker contacts, no magnetic transient is induced into the breaker’s current transformer. This can prevent the risk of inductively tripping a breaker control (bus differential relay). The resistance reading is displayed directly in micro-ohms or milli-ohms. No calculations are required to compensate for lead resistances.

Vanguard Auto-Ohm 100 Ampere Micro-Ohmmeter specifications:


Portable micro-ohmmeter

Physical Specifications

16.8”W X 12.6”H x 12.0”D (42.7 cm x 32.0 cm x 30.5 cm); Weight: less than 21 lbs (9.5 kg)

Input Power

100 – 240 Vac, 50/60 Hz

Resistance Reading Range

1 micro-ohm – 300 milli-ohms (1 micro-ohm resolution); Accuracy: ±1% reading, ± 1 count

Test Current Range

Thermally-protected DC power supply, 10 Amperes – 100 Amperes

Test Duration

5 seconds – 120 seconds, selectable


1-inch high back-lit LCD Screen (16 characters by 2 lines); viewable in bright sunlight and low-light levels

Internal Test Record Storage

Stores and can display last 3 readings

Computer Interface

RS-232C port (19,200 Baud) for factory calibration and diagnostics


Designed to meet IEC61010 (1995), UL61010A-1, CSA-C22.2 standards


Operating: -10°C to 50° C (15°F to +122° F); Storage: -30° C to 70° C (-22°F to +158° F)


90% RH @ 40°C (104°F) non-condensing


2,000m (6,562 ft) to full safety specifications


30-foot (#1AWG) test cables, ground cable, power cord


Transportation case, 15-foot test cables, C-clamps, Handspike

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