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  2. Four-terminal sensing - Wikipedia

    en.wikipedia.org/wiki/Four-terminal_sensing

    Four-point measurement of resistance between voltage sense connections 2 and 3. Current is supplied via force connections 1 and 4. In electrical engineering, four-terminal sensing (4T sensing), 4-wire sensing, or 4-point probes method is an electrical impedance measuring technique that uses separate pairs of current-carrying and voltage-sensing electrodes to make more accurate measurements ...

  3. Contact resistance - Wikipedia

    en.wikipedia.org/wiki/Contact_resistance

    Because contact resistance is usually comparatively small, it can be difficult to measure, and four-terminal measurement gives better results than a simple two-terminal measurement made with an ohmmeter. In a two-terminal measurement (as with a typical ohmmeter), the current used to make the measurement is injected through the measurement leads ...

  4. Kelvin bridge - Wikipedia

    en.wikipedia.org/wiki/Kelvin_bridge

    The operation of the Kelvin bridge is very similar to the Wheatstone bridge, but uses two additional resistors. Resistors R 1 and R 2 are connected to the outside potential terminals of the four terminal known or standard resistor R s and the unknown resistor R x (identified as P 1 and P′ 1 in the diagram).

  5. Ohmmeter - Wikipedia

    en.wikipedia.org/wiki/Ohmmeter

    An analog ohmmeter. An ohmmeter is an electrical instrument that measures electrical resistance (the opposition offered by a circuit or component to the flow of electric current). Multimeters also function as ohmmeters when in resistance-measuring mode. An ohmmeter applies current to the circuit or component whose resistance is to be measured.

  6. Post office box (electricity) - Wikipedia

    en.wikipedia.org/wiki/Post_office_box_(electricity)

    A typical post office box is in a wooden box with a hinged lid and a metal or bakelite panel showing circuit connections. Coils of wire are wound non-inductively, mounted in the body of the box, and have a negligible temperature coefficient. Pairs of ratio arms are each 5 10 20 ohms. Resistance arms contains a number of coils from 1 to 5000 ...

  7. Portable appliance testing - Wikipedia

    en.wikipedia.org/wiki/Portable_appliance_testing

    A common label for certifying that a device has been tested. In electrical safety testing, portable appliance testing (PAT inspection or PAT testing) is a process by which electrical appliances are routinely checked for safety, commonly used in the United Kingdom, Ireland, New Zealand and Australia.

  8. Multimeter - Wikipedia

    en.wikipedia.org/wiki/Multimeter

    A multimeter (also known as a volt-ohm-milliammeter, volt-ohmmeter or VOM) [1] is a measuring instrument that can measure multiple electrical properties. [ 2 ] [ 3 ] A typical multimeter can measure voltage , resistance , and current , [ 4 ] in which case can be used as a voltmeter , ohmmeter , and ammeter .

  9. Megohmmeter - Wikipedia

    en.wikipedia.org/wiki/Megohmmeter

    Megohmmeter M1101M. A Megohmmeter or insulation resistance tester, is a special type of ohmmeter used to measure the electrical resistance of insulators. [1] Insulating components, for example cable jackets, must be tested for their insulation strength at the time of commissioning and as part of maintenance of high voltage electrical equipment and installations.