FREQUENCY METERS

1-50 The pointer on the right-hand dial (fig. 1-46) registers 1 kilowatt-hour, or 1,000 watt-hours, for each division of the dial. A complete revolution of the hand on this dial will move the hand of the second dial one division and register 10 kilowatt-hours, or 10,000 watt-hours. A complete revolution of the hand of the second dial will move the third hand one division and register 100 kilowatt-hours or 100,000 watt-hours, and so on. Figure 1-46.—Watt-hour meter. Accordingly, you must read the hands from left to right, and add three zeros to the reading of the lowest dial to obtain the reading of the meter in watt-hours. The dial hands should always be read as indicating the figure which they have LAST PASSED, and not the one they are approaching. Q60. Why would you use a hook-on voltameter instead of a multimeter? Q61. What electrical quantity is measured by a wattmeter? Q62. What electrical quantity is measured by a watt-hour meter? Q63. What is the quantity shown on the watt-hour meter in figure 1-46? FREQUENCY METERS All alternating voltage sources are generated at a set frequency or range of frequencies. A frequency meter provides a means of measuring this frequency. Two common types of frequency meters are the vibrating-reed frequency meter and the moving-disk frequency meter. Vibrating-Reed Frequency Meter The vibrating-reed frequency meter is one of the simplest devices for indicating the frequency of an ac source. Vibrating-reed frequency meters are usually in-circuit meters. They are used on power panels