SU911395A1 - Device for testing ac measuring instruments - Google Patents

Description

I

This invention relates to a measurement technique and can be used to calibrate alternating current devices.

A device for calibrating a device comprising a signal generator, a voltage indicator, a relationship meter, and a voltage divider U. is known.

The closest in technical essence to the invention is a device comprising a generator of calibrated signals and a calibration instrument t, 2l.

A disadvantage of the known devices is low calibration accuracy.

The purpose of the invention is to improve the accuracy of calibration of ac measuring instruments having an output signal in the form of a direct current.

This goal is achieved by the fact that, in a device containing a calibrated test signal generator and an exemplary DC test device, the calibrated test signal generator contains N parallel branches connected to the reference-frequency generator and consisting of each element of adjustable delay . Dani phase shift,. Counter, digital-analog function generator with filter / low frequencies at the output, with the output of each branch connected to a switch connected

10 with a turning instrument with a measuring instrument and with a test apparatus under test.

Since the magnitude of the steps of the digital-analog function generator is set with the aid of constant current equipment and the same apparatus, the value of the constant component at the output of the alternating current device being tested, it is possible to achieve the same accuracy as that

20 constant current.

The drawing shows a block diagram of the proposed three-channel device.

The device comprises a reference frequency generator 1, adjustable delay elements 2-k, counters, digital-analog generators 8-10 functions combined with low-pass filters, a rotatable device 11, a DC measuring device 12 and a switch 13.

To obtain the required accuracy of the calibrated test signals, all discrete states of the counters 5-7 are set alternately, while using the switch 13 they connect the calibration measuring device 12 to the outputs of the generators 8-10 and, by adjusting the parameters of the generators, achieve the calculated values of the signals from their outputs.

Then set the required frequency value, oscillator 1, set the appropriate code values to the control inputs of the 2-elements of the adjustable delay, and the calibration measuring device 12 is connected by a switch 13 to the output of the device 11 to be turned on.

The error of the device to be tested 11 is defined as the difference between the calculated value of the signal at its output for the given parameters of the signals from the generators 8-10 and the actual value of the output signal of the device being turned.

The proposed device greatly simplifies the process of calibration of measuring devices in a wide range of frequencies, phases, amplitudes and forms of b - - lines.

Claims (2)

1. USSR author's certificate, If, cl. G 01 R 35/00, 19b9. 2. Work of the institutions of the Committee. Issue 39 (99). L., Standartgiz, 19bO, p. 130lifl.