| 摘要 |
<p>An auto-ranging system for an electronic watt-hour meter includes a current transformer for measuring the electrical current in at least one line of an electrical power consuming system. The measured current is converted to a voltage which is proportional to the measured current by means of a current/voltage converter. A means responsive to the output of the current transformer incrementally varies the gain of the current/voltage converter inversely as the level of the measured current reaches each of a plurality of successively increasing discrete current levels. The output of the current/voltage converter is multiplied by the line voltage which is detected by a potential transformer with the output of the multiplier being coupled to an analog-to-pulse rate converter. The analog-to-pulse rate converter generates a pulse train having a pulse rate which is proportional to the product signal at the output of the multiplier. A means responsive to the output of the current transformer incrementally varies the pulse rate of the pulse train as the measured current reaches each of the successive plurality of discrete current levels so that the pulse rate varying means compensates the variance of the gain of the current-to-voltage converter. Thus, a watt-hour meter is provided which has a substantially constant gain and an exceedingly large dynamic range.</p> |
