| 摘要 |
In the direct measurement of thermal energy transferred in heating or air conditioning installations, the difference between voltages from outflow and return flow temperature sensors is integrated during a first timing period and then discharged during a second timing period with a constant current to operate a gate passing a number of pulses proportional to the voltage difference. The first and second timing periods are initiated by impulses from a volume flow sensor. During non-timing-period intervals a reference voltage capacitance is set by integrating circuit feedback. In collection of data from a plurality of thermal energy transfer meters, inputs from the meters are scanned at rates greatly exceeding the pulse frequencies to increment or decrement the count in digital filter stages of corresponding pairs of counters depending upon whether sensed voltage levels are opposite or equal to the last accepted voltage level as recorded in a most significant stage of the digital filter.
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