An ohmmeter is an instrument used to measure the electrical resistance of a conductor. In normal usage, the ohmmeter operates by using the voltmeter to measure a voltage drop, then converting this reading into a corresponding resistance reading through Ohm's law. If the current is known, the voltage drop across the unknown resistance may be read to give the resistance directly. If the current is not known, or if it is not possible to measure the voltage across the unknown directly, reading the voltage drop across a known resistance in the same circuit will give the current, and once this voltage is subtracted from the total drop for the circuit, the voltage drop across the unknown, and thus its resistance, may be found, and displayed on the ohmmeter. A micro-ohmmeter is an ohmmeter for the measurements of very low resistances.
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High accuracy Megohmmeter |
1 kΩ -100 TΩ; 0.5% |
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High accuracy Micro-Ohmmeter
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The GenRad 1863 Megohmmeter is the choice for production and inspection tests. The 1863 will measure
resistance at any of five common test voltages up to 500VDC, has fewer controls, and is the lower priced model. It is the best selection for those applications requiring a lesser voltage and resistance range.
The GenRad 1864 Megohmmeter is the choice for more demanding applications. It is the more flexible of the two instruments. The test voltage can be set to any value from 10VDC to 109VDC in 1-volt steps and to 1090VDC in 10 volt steps. Thus the 1864 can be set to any common, or uncommon test votage for ceramic, mica or paper capacitors, or other devices. The reverse resistance of rectifiers can be readily measured; the low test voltages are especially useful in measuring solid state diodes. An additional range permits measurements up to 200TW (2 x 1014W)
LOM-510A Micro-Ohmmeter
The LOM-510A Micro-Ohmmeter has 4½ digits, 002% basic accuracy and 1 μΩ resolution. Its 4-terminal measurement technique eliminates lead resistance errors and 80 dB of ac noise rejection provides rock-steady readings even in noisy locations The micro-ohmmeter comes with rugged 4-terminal test clips and a large selection of optional probes,
