Common use of Frequency Response Clause in Contracts

Frequency Response. 4The crest factor of a Watt-hour meter is often provided for both current and voltage. For current, it is the ratio of the peak current to the RMS current in a specific current range. When only one crest factor is given, it is usually for current. An average True RMS Watt-hour meter has a crest factor in the range of 2:1 to 6:1. Another issue to consider when selecting a Watt-hour meter is the frequency response rating of the meter. Electronic equipment that contains switching power supplies causes harmonics (odd harmonics typically up to the 21st). These harmonics must be accounted for in measurement, or the energy and power consumption will be inaccurate. Accordingly, EPA recommends that manufacturers purchase Watt-hour meters that have a frequency response of at least 3 kHz. This will account for harmonics up to the 50th, and is recommended by IEC 555. Manufacturers will probably want a meter that can provide resolution of 0.1 W. Accuracy Another feature to consider is the resulting accuracy that can be achieved. Catalogues and specification sheets for Watt-hour meters typically provide information on the accuracy of energy and power readings that can be achieved at different range settings. When measuring a product that is very close to the MOU specifications, Partners will need to set up a test that will provide greater accuracy. For example, if the resulting accuracy for a Watt-hour meter at the test settings is + 0.5 W, then be sure the measured power consumption of the MFD or upgradeable digital copier is within at least 0.5 W of the MOU specification. Watt-hour meters should be calibrated every year to maintain their accuracy. QUESTIONS AND ANSWERS REGARDING TESTING PROCEDURES FOR ENERGY STAR® MULTIFUNCTION DEVICES AND UPGRADEABLE DIGITAL COPIERS Q: Are these testing requirements mandatory?