Search results
Results from the WOW.Com Content Network
A multimeter can use many different test probes to connect to the circuit or device under test. Crocodile clips, retractable hook clips, and pointed probes are the three most common types. Tweezer probes are used for closely spaced test points, as for instance surface-mount devices. The connectors are attached to flexible, well insulated leads ...
Insulation testers that relied on a hand cranked generator operated on the same principle. This ensured that the indication was wholly independent of the voltage actually produced. Subsequent designs of ohmmeter provided a small battery to apply a voltage to a resistance via a galvanometer to measure the current through the resistance (battery ...
A minimum acceptable resistance value is usually specified (typically in the mega ohm (MΩ) range per circuit tested). Multiple circuits having a common return may be tested simultaneously, provided the minimum allowable resistance value is based on the number of circuits in parallel. Five basic isolation test configurations exist: [3]
Conductivity could in principle be determined using the distance between the electrodes and their surface area using Ohm's law but generally, for accuracy, a calibration is employed using electrolytes of well-known conductivity.
Variations in the electrical conductivity and magnetic permeability of the test object, and the presence of defects causes a change in eddy current and a corresponding change in phase and amplitude that can be detected by measuring the impedance changes in the coil, which is a telltale sign of the presence of defects. [5]
Multifunction testers are able to perform continuity tests (or low ohms resistance tests) and insulation resistance tests (or high ohms resistance tests) and they may also be able to perform earth fault loop impedance tests, prospective short-circuit current tests, earth electrode tests and RCD tests.
The original AVOmeter was designed to measure direct current (3 ranges, 0.12, 1.2 & 12 A), direct voltage (3 ranges, 12, 120 & 600 V) and resistance (single range, 0 - 10,000 ohms, 225 ohms mid-scale). All ranges could be selected by a single rotary switch which set both the function and the range value.
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.