Rectifying Electrical Measuring Instrument

Rectifying Electrical Measuring Instrument 

a device used to measure the characteristics of an alternating current. It consists of a current rectifier and a permanent-magnet instrument, which measures either the mean value of the rectified current or the relation between the mean values of rectified currents. Semiconducting instruments usually serve as the rectifying element.

A rectifying electrical measuring instrument may be used to measure voltage, current intensity, frequency, phase, or power. In a simplified circuit of this instrument for measuring the intensity of an alternating current, diodes form the double half-period circuit of rectification, and the mean value of the rectified current is measured with a permanent-magnet instrument. The switching of a current into the circuit in a series with a rectifying circuit of added resistance permits the use of this circuit to measure the AC voltage. The scale of the permanent-magnet instrument is usually calibrated in effective values of the voltage or intensity of an alternating current with a sinusoidal form. In actuality, the deviation of the indicator of the permanent-magnet device is proportional to the mean value of the voltage and current intensity. The rectifying electrical measuring instrument is rarely used for measuring power.

As a rule, these instruments are all-purpose multi-limit measuring devices with a high degree of sensitivity. Their disadvantages include a low degree of accuracy and the dependency of readings on the form of the AC curve and on the temperature of the surrounding environment.

REFERENCES

Arutinov, V. O. Elektricheskie izmeritel’nye pribory i izmereniia. Moscow-Leningrad, 1958.
Kurs elektricheskikh izmerenii, part 1. Edited by V. T. Prytkov and A. V. Talitskii. Moscow-Leningrad, 1960.

V. P. KUZNETSOV