To isolate bus faults, all power source circuits connected to the bus are opened electrically by circuit breakers responding to relay action, by direct-acting trip devices on low-voltage circuit breakers, or by fus.
[pdf] An un-amplified analog multimeter combines a meter movement, range resistors and switches; VTVMs are amplified analog meters and contain active circuitry. For an analog meter movement, DC voltage is measured with a series resistor connected between the meter movement and the circuit under test. A switch (usually rotary) allows greater resistance to be inserted in series with the meter movement to read hi.
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