To carry out selection of respective circuits and power calculation on the basis of a regular signal by means of a selector by providing the selector periodically selecting one of inputs and a central processing unit CPU calculating power on the basis of an output from a hold circuit.
In a measurement monitoring device 50, an R-S voltage 51 and an S-T voltage 52 are inputted, and measurement of circuit is carried out in circuits 1-N. From the circuit 1, an R-phase current 531 and a T-phase current 541 are inputted to the device 50, and the voltages 51, 52 are common in all of the circuits. For measurement, the voltage 51 is transformed to a proper voltage value by means of a transformer VT57, while the S-T voltage is transformed into a proper voltage value by means of a transformer VT58. A current matching each circuit is transformed into a proper current value by means of a transformer CT for measurement. That is, in the circuit 1, the R-phase current 531 and the T-phase current 541 are transformed by means of transformers CT591, CT601 individually. An amplified signal is held in a sample and hold circuit 75 and taken into an A/D converter on the basis of a signal 76 outputted from a CPU 77, and then, the signal value is converted into a digital value so as to be stored in a memory 82.
GOTOU SATOKO
MARUNOUCHI SATORU
SAKAI SATOSHI
KIMURA TOSHIKO
NAKAJO ENGINEERING CO LTD
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