| 摘要 |
<p>The electric power measuring appts. includes a power-current converter (1) for detecting the electric power of a line to be measured w.r.t. both the directions of one and the opposite, and an integrator (3) receiving the output of the converter. A circuit (4) discriminates the level of the output of the integrator. A circuitry (5,6,7,8) inverts the direction of change in the integrator output by applying a constant current, having the opposite polarity to the input of the integrator from the converter, to the integrator in addition to the input from the converter in response to the discrimination signal. Measuring units (12,14) obtain pulse frequency dependent on the change of the integrator output. Switches (21,22) are adapted to change over the polarity of the input of the integrator from the power-current converter. A controller circuit (9,10) changes over the switches and selects one of the measuring units according to the direction of power transfer, when the direction of power transfer is inverted, such that the integrator output exceeds a predetermined level. Power measurement w.r.t. both the directions of one and the opposite can be thus exactly performed by use of only one current-frequency converter. The electric power measuring appts. is, therefore, suitable for electric power measurement w.r.t. the two directions of energy transfer.</p> |
