SU457949A1 - Device for automatic checking of electricity meters - Google Patents

Description

one

The invention relates to electrical measuring equipment and can be used in the adjustment and calibration, in the manufacture or repair of mass electrical measuring instruments of electrical energy.

Similar devices are known that contain one or several exemplary devices with pulse sensors, pulse sensors of turns of meters being turned, pulse counters and program-switching blocks, have complex circuits with a large number of measuring channels depending on the number of calibration modes.

To simplify devices and allow independent and parallel verification of a large number of counters with one set of exemplary instruments, each calibrated meter is connected in the proposed device to the circuit of exemplary instruments through a separate software-matching unit, which is simultaneously connected to the pulse meter of the meter being turned on. As the pulse counter, reversible counters of limited capacity are used, the number of reverses of which determines the sign of the error of the counters.

In the drawing is a block diagram of the proposed device.

It consists of a centralized unit of exemplary devices, which includes one

or several exemplary electricity meters 1, G ... with pulse sensors 2, 2 ... allowing to obtain a significant number of pulses per revolution of the disk. The number of pulses taken in one revolution is determined by the expression:

-Tp

taken for

. where n is the number of pulses, one turn of the disk;

7- error from the discreteness of reference.

So with a given reference error equal to 0, 1% (the most appropriate value) imp / rev. In the case of setting a measurement cycle equal to t revolutions, the number of pulses received per revolution, respectively, decreases by a factor of t.

The need to install several exemplary devices arises when verification is necessary to be carried at different power factors. According to the standards in force in the USSR, it is necessary to install two exemplary devices operating in the mode and co8f 0.5.

The same circuits, in which exemplary devices are included, by means of program-switching blocks 3.3 ... include test instruments 4.4 ..., near the disks of which the sensors 5.5 ... are located. The outputs of the sensors are connected to permitting inputs pulse counters 6.6 ... with the second, counting inputs of which are connected to the outputs of the rotational speed sensors of exemplary devices 2.2 ... There are connected to the output circuits of the pulse counters 6.6 ... counting printing blocks 7.7 ....

Common to the entire device are the blocks 1.1 ..., 2.2 ... and 8. The blocks 3.3 ...- 7.7 ... are installed depending on the number of electric power meters to be turned.

For testing (calibrations) in different modes, the meter being turned on is included in the model circuit through a special software switching unit 3, which contains, besides the switches (relays), a matching element, for example, current and voltage transformers.

The pulse counters are subtractive, in the memory of which, before the measurement is started, a certain number is inserted by the signal from the software device, which decreases when the counting pulses arrive at the input. When going through the zero state, the counter switches to the summation of pulses while simultaneously issuing a signal about a change in the sign of the error.

The program-switching unit 3 automatically switches the turned-on meter 4 into the mode according to a given program, simultaneously input the required number into the memory of the meter 6, and connects the input of this meter to the sensor 2 of that exemplary device, the circuit of which is turned on by the meter being turned on. However, the counting of pulses does not occur, because a pulse from the sensor 5 of the instrument being scanned has not arrived at the permissive input of the pulse counter.

When the mark on the disk of the scanned device passes the sensor 5, a command pulse is generated, allowing the start of the count in block 6 and the counting of the pulses from block 2 begins. This count continues until the second pulse from the speed sensor 5 arrives ending one full turn. After this pulse arrives, the counting in block 6 is stopped and, from block 3, the command is sent to the block-print unit 7, which records the number of pulses remaining in the counter. This number will be proportional to the failure rate of the device under test, since with zero failure by the time of the prohibitory impulse from unit 5, the impulse counter will be in the zero state.

In the case of a positive gauge of the instrument being tested, a pulse fixing the end of one turn of the disk of this instrument will come to the input of counter 6 earlier than the recorded number is subtracted from its memory and, therefore, the remaining number will correspond to the error value, and the sign of the error will be written into 1 positive.

With a negative error of the test device, the prohibiting impulse should come after the number recorded in it has been subtracted from counter 6. However, when the counter reaches the zero position, it switches to the summation of pulses. Naturally, in this case, after the prohibiting impulse arrives, counter 6 will count the number of impulses proportional to the fault rate. However, a sign of discrepancy

will be recorded in block 7 by the inverse, because at the moment when the counter 6 passes through the zero position from it, block 7 sends a signal about the polarity change of the fault.

When it comes to verification

devices with obviously low error values (in the production process after adjustment operations), the device can be further simplified by installing 6 pulse counters in it with a reduced memory capacity

and having executed them under the scheme "subtraction - summation - subtraction. In this case, the magnitude of the error is still determined by the number recorded in the pulse counter memory, while the sign of the error is determined by

the number of counter switches from one counting mode to another. With an even number of faults, the sign is positive, with an odd number - negative. It is easy to decipher this position with the help of a scheme fixing the “even-odd” delivery, for example, using a normal trigger.

Subject invention

1- A device for automatic calibration of electrical energy meters, containing one or several exemplary devices with pulse sensors, pulse sensors of turns of countable meters, pulse counters, program-switching blocks, characterized in that, in order to enable a large number of independent and parallel calibration counters with one set of exemplary devices,

Each calibrated meter is connected to the circuit of exemplary devices through a separate software matching unit, which is simultaneously connected to the pulse meter of the meter being turned on.

2. Device n. 1, characterized in that, in order to simplify and increase its power, reversible counters of limited capacity are used as pulse counters, the number of reverses of which

determines the sign of error of the counters.