時間：2011-03-11 23:18來源：藍天飛行翻譯 作者：航空 點擊：次
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voltage spike (electrical disturbance). A sudden, short-duration surge of high voltage along a power line or in a piece of electrical equipment. Voltage spikes are induced into the system by lightning or by some inductive equipment being turned off. These high-voltage spikes can damage many types of semiconductor devices. Surge protectors are used to bypass voltage spikes to ground, so they cannot cause damage. voltammeter (electrical measuring instrument). An instrument that can measure both volts and amperes. A switch is built into the instrument to change its function. volt-amp. The basic unit of apparent power in an AC circuit. A volt-amp is the product of the circuit voltage and all of the current, regardless of its phase. A volt-amp differs from a watt in that a watt is a measure of true power and is the product of the circuit voltage and only that current in phase with it. voltmeter. An electrical measuring instrument used to measure electrical pressure. Most of the commonly used voltmeters are actually current measuring instruments in series with a high resistance which limits the amount of current that can flow through the meter. The deflection of the meter pointer is proportional to the voltage across the meter and resistance combination. voltmeter multiplier. A precision resistor in series with a voltmeter mechanism used to extend the range of the basic meter or to allow a single meter to measure several ranges of voltage. voltmeter sensitivity (electrical measuring instrument specification). The amount of current needed to move the pointer of a voltmeter across its full scale. Voltmeter sensitivity, which is expressed in terms of ohms per volt, is found by dividing the total resistance of the meter by its full-scale voltage. volt-ohm-milliammeter. See VOM. |
