SU1485137A1 - Method of measuring effective ac voltage - Google Patents

Description

The invention relates to electrical engineering. The purpose of the invention is to increase the measurement speed - is achieved by the fact that the measured voltage is detected, form an auxiliary voltage, the pulse frequency of which is set. The invention relates to electrical measurement technology.

The purpose of the invention is improving the measurement performance.

On Fig, 1 shows a timing diagram explaining the essence of the method; on Fig, 2 is a block diagram of devices for implementing the method.

Measured voltage and _k (s)

(figa) detect, highlighting, for example, a positive half-cycle. The first auxiliary voltage 1C (s) is formed (Fig. 16), the pulse frequency of which is proportional to the voltage and _k (s), and the duration is constant. The detected voltage υ _χ (ϋ)

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They are proportional to the detected voltage, and the duration is constant, the detected voltage is integrated over the intervals of the auxiliary voltage pulses, a linearly varying voltage is formed and integrated. The formation and integration of a linearly varying voltage at time intervals between the moments of the end of the auxiliary voltage pulses and the moments of equality of the results of integration of the detected voltage and the linearly varying voltage and determination of the effective voltage value by measuring the total duration of these time intervals makes it possible to reduce the measurement time to a half-period of the measured voltage. A device for implementing the method is described. 2 ill.

integrate, and integration is carried out only at intervals of the action of the pulses and <(b). By the moment of the end of the positive half-cycle of the voltage and _k (C), the integrated voltage and _{int (} (g) (Fig. 1c) are proportional to the square of the effective voltage value υ _χ (κ) .

At time C _(at shear first voltage, and (c) pulse begin to form second auxiliary linearly increasing voltage and ₄ (c), by integrating the voltage which is obtained _ing2 and (c) (1D), at the time of equality and _"um , ( ^c ^) ^{, e} and _ith ^ (^ 2.) pause

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the formation of stresses and ^ (c5 and and _int ^ (s). So get the first time interval With _r "] (Fig, -1D).

by a cut of the second impulse 11, (1;) at the moment of time, the formation of the voltage u ^ (C) of the s' level and _r (£ ₂ ) = u and _r (b ^) and the voltage and _nth (s) from the level ^and int r (C ₃ ) · Integration is continued until the time bd-, when both _ing1 (C) = and _Yigg (1: _h .>. A second time interval is obtained

And so on, right up to the end of the positive half-interval and _to (c).

The sum of all the intervals obtained is 15 Έ [[, [Lee ^ З ··· is proportional to the current voltage напряжения _χ (ΐ;). The measurement time of the actual voltage value according to this method is half the 20 period of this voltage '.

A device for implementing the method comprises a control unit 1, a switch 2, a voltage-to-frequency converter 3, an amplifier-driver 4, ge ~. 25 sawtooth nerator 5, switches 6 and 7, inverter 8., integrators 9 and 10, element 11, comparison unit 12, trigger 13 ,. block 14 counters, generator 15 counting pulses, 30

The input of the converter 3, the input of the amplifier-driver 4 and the first input of the key 2 are connected to the input of the device, the output of the key 2 is connected to the first input of the key 7, the first output of the converter 3 is connected to the second input of the key 2, and the second output is connected to the first input of block 1 and the second input of the trigger 13. The output of the amplifier-driver 4 is connected to the input of the inverter 8 and to the second input of the key 7, the output of which is connected to the first input of the integrator 10, the second input of which is connected to the output of the element And 11, the third input of the block 1 and the second input of the integrator 9 , Inverter 8 output nen with the first input of the element And 11, the output of the integrator 10 with the second input of the block 12, the output of the block 1 through the generator 5 is connected to the first input of the key 6, the output of which is connected to the first input of the integrator 9. The output of the integrator 9 is connected to the first input of the block 12, the output of which is connected to the second inputs of block 1, key $$ b and of the element And 11 and with the first input of trigger 13, the output of trigger 13 is connected to the first input of block 14, the second input of which is connected to the output37

generator house 15, and the output is the output of the device.

The method is as follows.

At the moment of the transition of the measured voltage u ^ (C) from the region of negative value to the region of positive, the amplifier-driver 4 is triggered by the signal from which the key 7 opens. Through the key 2, controlled by the voltage-to-frequency converter 3, and the key 7, the converted measured voltage is supplied to the first input of the integrator 10. By the cutoff of each of the pulses and, (C) at time moments C ,, C ,,,., C ₍ · a signal appears at the second input of converter 3, which is fed to the first input of block 1 and to second trigger input 13, by this signal Lock 1 comprises a work sawtooth voltage generator 5, and the trigger 13 allows the unit 14 count pulses from the generator 15. The sawtooth voltage output from the generator 5 through the switch 6 is supplied to a first input of the integrator 9. The voltage and _BMI, (ϊ) output from the integrator 10 and voltage

^{with you} x ⁰ Yes ^and integrator 9 are compared by block. 12. At the moments of their equality,.,., ,, block 12 generates a signal that is fed to the second inputs of block 1 and key 6, as well as to the first input of trigger 13. By this signal, block 1 stops the sweep of the ramp voltage at the generator output 5, the key 6 disconnects the first input of the integrator 9 from this voltage, and the trigger 13 prohibits the counting of pulses to the block 14.

At the time of the transition of voltage _to (c) from the region of positive value to the region of negative amplifier, the driver 4 locks the key 7, stopping the flow of the measured voltage to the input of the integrator 10,

In block 14, at this moment, a sum of impulses is formed, proportional to the sum of all time intervals' 1 ^ - Ϊ "1 + ι" 1 ·

The signal from the output of the amplifier-former 4 is inverted by the inverter 8, and “1” is set at the first input of the element And 11. At the time when the next (last) comparison _occurs and _{ICht <} (b) and and _mtg (s) at the output of the block 12 a signal appears,

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by which the next sweep of the sawtooth voltage and its integration is made. At the same time, the element And I1 gives a signal through which block 1 resets the generator 5 and the integrators 9 and 10.

Claims (1)

Claim A method of measuring the effective value of the alternating voltage, which consists in linearly detecting the measured voltage, forming the first auxiliary voltage, the pulse frequency of which is set proportional to the detected measured voltage, and the duration constant, integrate the detected measured voltage at intervals of 20 pulses of the first auxiliary voltage, form the second auxiliary ramp voltage and integrate it, characterized in that, in order to improve performance, the second auxiliary ramp voltage is formed and integrate at time intervals between the moments of the end of the pulses of the first auxiliary voltage and the moments of equality of results integrating the detected measured voltage and the second auxiliary ramp voltage The measured voltage is determined by measuring the total duration of the time intervals la. half period of the measured voltage, Phase 1 1485137 Riga 2