SU197001A1 - DEVICE FOR AUTOMATIC TESTING OF ELECTRIC MEASUREMENT INSTRUMENTS - Google Patents

Description

Devices for automatic calibration of electrical measuring instruments are known, comprising an input driver applied to a scanned device, a reference signal source, a differential device, the output of which is connected through a key circuit with a device for recording the results of calibration, a device for tracking a pointer of a scanned device, and a registration registration device. pointer with check marks, which controls the key scheme.

The proposed device differs from the known ones in that it is equipped with a switch for the rate of change of the input signal associated with the input driver and the output switch of the key circuit; two gauges of the accuracy of the instrument being scanned, for example, measuring devices of a time-pulse converter, the inputs of which are connected to the output of the said key circuit, and the outputs are connected to a dynamic error calculating device, for example, to a digital computing device; a subtraction circuit, one input of which is connected to the output of the dynamic error calculation device, the other - to the output of one of the error meters of the device being scanned, and the output is connected to the device for recording the results of verification.

This difference allows to exclude a dynamic error of verification.

The drawing shows a functional diagram of the described device. The scale of the instrument 1 to be checked is in the field of view of the device 2 for registering registrations of the pointer with the points being checked, and the pointer is in the field of view of the device 3 for tracking the pointer. Devices 2 and 3,

rigidly interconnected form a mobile unit 4. The output of the registration device is connected via a delay circuit 5 to the switch 6 of the reference signal source 7 and to one of the inputs of the key circuit

8. The output of the source of the reference signal 7 is connected to the first input of the differential device. The second input I of which is communicated through the scale converter W with the driver // input signal, and the output through

the amplifier 12 is connected to the second input of the key circuit 8. The input driver is in communication with a calibrated instrument. The switch 13 of the rate of change of the input signal controls the driver //

and the switch 14 of the output of the key circuit, connecting the output of the latter either to the meter 15 or to the meter 16 of the accuracy of the instrument being turned. The outputs of the meters 15 and ./5 are connected to the device 17

This is connected with the first input of the subtraction circuit 18, the second input of which is connected to the output of the meter 16 of the instrument being scanned, and the output with the device 19 for recording the results of the calibration.

The proposed device works as follows.

In the initial state before the start of the scanner, the indicator of the instrument being scanned / is aligned with the zero point of the scale and is in the field of view of the pointer tracking device 3. In the zero view of the registration registration device 2, there is either only one zero mark, or another number of neighboring marks depending on the principle of operation of device 2, which can be used, for example, a device containing an optical system, a slit aperture and a photoelectric converter with an electronic device that outputs a signal at the moments of combining the pointer with calibrated marks.

As an indicator tracking device, for example, a slit-aperture optic-electronic tracking system with a photoelectric converter or a television tracking system can be used. The output of the key circuit 8 is connected to the error meter 15. When the input signal, for example, linearly increasing, is sent from the imaging unit 7 / to the rotating instrument / instrument, the pointer of the latter begins to move along the plates. The pointer tracking device moves the movable unit 4 following the pointer. At the same time, the input signal through the scaled converter 10, set in accordance with the measurement limit of the device under test, is fed to the second input of the differential device 9, the first input of which receives an exemplary signal from the source of the reference signal corresponding to the first test point of the device 1. The difference of these signals is the output of the differential device 9 is amplified by the amplifier 12 and is fed to the second input of the normally closed key circuit 8. At the time of passage, the pointer over the first point being checked A control electrical impulse appears at the output of the registration device 2 in combination, opening the key circuit 8 for the time determined by the duration of this impulse. During this time, the amplified difference signal passes through the key circuit to the input of the error meter 15. The latter measures this signal, which is proportional to the accuracy of instrument 6i for the first calibrated mark, and the speed of the AC, the change in the input signal.

As an error meter, it can be used, for example, when checking on direct current, a time-pulse converter device that converts the voltage of a difference signal in a time interval filled with exemplary frequency pulses, the number of which in this interval is proportional to the difference signal being measured . The control pulse from the output of the registration registration device 2 also goes to the switch 6 of the source of the reference signal 7 through the delay circuit 5. Through the delay time determined by the required time for measuring the error, the switch 6 connects to the differential device 9 a reference signal corresponding to the second check mark sckal In this case, the key scheme is already closed, and the difference signal is not

passes on the gauge of overlap. At the moment of combining the pointer with the second calibrated mark, the described measurement cycle repeats and after it finishes, the switch connects the reference signal corresponding to the third calibrated mark to the first input of the differential device 9, thereby preparing the device for calibrating this third point of the gauge. Similarly, all other verified (digitized) scale marks are calibrated with a continuous increase in the input signal to the maximum value and a subsequent reverse decrease to zero at the rate of its change.

With such a signal, the meter 15 determines the number of errors Sis, ofj, ... o / g 3 | as the input signal rises and the number of bugs is 5h (1) ofSl (i) (t)

nosthey tiiy, chu, ... oiy, ... oiy when wowing

input signal at a rate of 1 / s (where m is the number of scales to be checked). When the decreasing input signal reaches a zero value, the switch 13 changes the input signal, activates a different rate of change Vc, the input signal of the driver // from zero to the maximum and vice versa and connects the output of the key circuit to the meter 16 using the switch 14.

Similarly, as described above, the process of registering the overlapping moments of the pointer with all calibrated marks occurs when the signal increases from zero to the maximum value and decreases from the maximum value to zero at a speed of EF, and the corresponding errors are measured.

Thus, the meter 16 determines the number of errors 6 () gfO)

with increasing input signal and p d

„“ (1) (2) (0l (t)

faults zy, y. .. razu., when the input signal decreases at a speed UszDevice of dynamic error calculation determines the values of dynamic errors for each calibrated mark, when the P increases, the input signal decreases at the speeds - Us, and Vc ,.

scale marks the dynamic error will be defined as

, (0 -.

6 (0

D2u -;

J p - 1

As a dynamic error calculation device 17, a digital computational device, drying, exists, its sequential storage of measured error values 6iB and 6iy for all verifiable scale marks at the input speed Vci and calculating dynamic errors 6d2v and bd2 can be used respectively, for increasing and decreasing of its input signal for the speed of EE. change it.

The dynamic errors of bdz and bdzu from the output of the device 17 successively as the pointer passes at a speed Vcj arrive at the first input of the subtraction circuit 18, the second input of which receives the errors 63 and Sjy for the corresponding, their adjustable marks from the output of the device. At the output of subtraction circuit 18, the difference of these values is obtained, which is proportional to the sought error of the calibrated scale marks, with the dynamic error minus, their increasing values of the input signal, i.e., for some i-th mark

, (i) (0 (0 3 (0 IO - (O

OOB - 02в - Од ,,, оу - JZy - Jflov

D2u

The final results of the BCV and TOC verification for all calibrated scale marks, determined respectively when the input signal increases and decreases, are recorded by the device 19 for recording the results of the calibration, for example, on a light board or recorded on a chart paper, or are in the form of a protocol of verification results.

Thus, the application in the proposed device two meters error

of the instrument being checked, switched by a switch depending on the rate of change of the input signal, the dynamic error calculation device and the subtraction scheme, which subtracts the dynamic error from the calibration result, eliminates the influence of the dynamic error and allows such a device to automatically calibrate the devices of the highest classes accuracy with a fairly small calibration time.

Subject invention

A device for automatic calibration of electrical measuring instruments, containing an input signal driver supplied to the instrument being scanned, a reference signal source, a differential device, the output of which is connected through a key circuit with a device for recording the results of calibration, a device for tracking the indicator of the instrument being scanned, and an indicator register registration device with verifiable scale marks, which controls the key scheme, characterized in that, in order to eliminate the dynamic verification error, it is equipped with reklyuchatelem speed variations of the input signal associated with the generator input

signal and switch output key circuit; two gauges of the accuracy of the instrument being checked, for example, measuring devices of a time-pulse converter, whose inputs are connected to the output

said key circuit, and the outputs are connected to a dynamic error calculation device, for example, a digital computing device; a subtraction circuit, one input of which is connected to the output of the dynamic error calculation device, the other - to the output of one of the meters of the scanned instrument, and the output is connected to the device recording the results of verification.