SU1429054A1 - Meter of mean square value of voltage of single pulse of random shape and duration - Google Patents

Abstract

The invention relates to electrical measuring and pulse engineering and can be used in testing devices, for example, to measure the current characteristics of circuit breakers. The purpose of the invention — extending the functionality by measuring the pulse duration — is achieved in that the meter of the rms voltage of a single pulse of random form and duration, containing a signal sensor 1, quad 4, reference element 8, integrator 13, comparator 2, trigger 9 , two counters 15, 18, a digital-to-analog converter 17, a multi-range integrator 6, a switching key 5, a source of reference voltage 10, a generator of 14 clock pulses, two blocks 7, 16 calculating the order, two g keys 3, 11, adder 19, key control unit 20. 2 Il.

Description

WITH

Yu

SP

I The invention relates to a pulse technique and can be used to test devices, for example, g | 1 to remove the current characteristics of a protection circuit, I the purpose of the invention is to enhance the functionality by measuring the pulse duration,

Figure 1 shows the block diagram of the I-meter rms value of a single pulse of random size and duration; FIG. 2 - time ™ foam diagrams for his work

The proposed meter contains a signal sensor 1, a comparator 2, a first key 3, a quad, a rator 4, switching 1Ts key 5, a multi-range integrator 6, the first block 7 calculating order, element 8 comparison, 9, source 10 reference voltage , | the second key 11, the third key 12, the first | integrator 13, the generator 14 of these pulses, the first counter 15, the second block 16 for calculating the order,; a digital-to-analog converter 17, a second counter 18, an adder 19, a control block 20,

The output of sensor 1 is connected to the input of comparator 2 and the first key 3, the output of comparator 2 is connected to the counting input of trigger 9, the input of the resolution of the first counter 15 and the control input of the first key 3, the output of which is combined with the output of the first integrator 13 and connected to the jc input Quad 4, the output is connected to the common contact of the switching key 5. The open contact of this key is connected to the input of the multi-range integrator 6, and the short circuit is connected to the analog input of the diffraction analogue converter, which digital inputs are connected The outputs of the first counter 15 are entered. The control input of the switch of key 5 is combined with the input of the resolution of the second counter 18, the first input of the key control unit 20 and is connected to the forward output of the trigger 9, the first reset input of which is connected to the output of the comparison element 8, one input of which is connected to the output of the digital-to-analog converter and the second input to the output of the multi-channel integrator 6 and the input of the first power calculation unit 7, the first output to the control input of the multi-channel integrator

6, and the second output is with the first input of the adder 19, the low-order bit of the code of which is connected to the second input of the key management unit 20. The second input of the adder 19 is connected to the first output of the second calculating unit 16, the input of which is connected to the overflow output of the first counter 15 5, and the second output to the input Yt-setting of this counter 15, the counting inputs of the first and second counters 15 and 18 are combined and connected to the generator of 1.4 clock pulses s, and the Reset inputs of these counters are combined with the second input Reset trigger 9 and connected to the Reset bus. The first and second outputs of the key management unit 20 are connected respectively to the control, the inputs of the second and third keys 11 and 12J, whose inputs are combined and connected to the output of the voltage source 10, and the outputs to the inputs of the first integrator 13,

The meter works as follows.

The multi-range integrator 6 with the order calculation unit 7 is made, for example, as an operational amplifier, the inverting input of which receives an integrating signal through a resistor, and switches the capacitance and bones to the feedback circuit of the operational amplifier. The ratio of the constant integration time of the integrator at different limits &.1510; 100, the integration starts with the shortest time constant G, (capacitance C included, in the feedback circuit of the operational amplifier). When the voltage at the output of the integrator reaches a certain threshold value, the threshold device connects the secondary capacitance C, the capacitance C 9C, and the charge redistribution on the capacitances, the voltage at the output of the operational amplifier decreases 10 times (this is equivalent to the integrator Before that, he worked with a constant time Cj 10 t,). Further integration is carried out with a capacity of C + C. YuS, i.e. 10 times more constant time. If the output voltage is inte-. the grator once again reaches the threshold value, the third capacity C, 9 is connected in the same way (C, - (- C). Thus, the time constant

multi-limit integrator 6 can take the value of sG, 10 cl. At the end of the integration cycle at the output of the primary integrator, the voltage is proportional to the integral of the input value, and the first calculator 7 for calculating the order at the second output gives the value code e, i.e. order of integrable value.

The first counter 15 is binary for 10 bits, when the value of the number reaches the counter, a pulse appears at the exit of the counter overflow, the arrival of the order of the second calculator 16, which, by the installation input, sets the content equal to 15 in the counter and switches it the counting input in such a way that the clock frequency starts to arrive at it 10 times less than before the overflow. At the next overflow, this procedure is repeated.

Thus, at the end of the measurement cycle, a binary code of the measured time interval is stored in the meter 15.

Change in the range of 100.-.- YuOO

ten

and on

the second output of the second order calculator 16 is the number of the counter range or the order of this number.

The digital-to-analog converter 17 represents a multiplier-divisor GAL.

The key management unit 20 is a combinational circuit that operates as follows. When there is a logical 1 signal at the first input of block 20 from the output

At time t, the comparator 2 triggers, the first switch t 3 turns on, and the voltage Ua (t) falls into the input of the quadrant 4. The voltage at the quadrature input is described by the expression

U (t) K, -U2 (t) K -K | X4t), (2) where K (is the conversion factor

quad.

From the output of the quadrant 4, the voltage and (t) enter the input of the integrator 6 through the opening contacts of the switching key 5. At the output of the integrator 6, the voltage increases according to the law -

U4 f U, (t) dt. (3)

Figure 2 at time t shows the transition of the integrator to the second limit. In general, the signal at the integrator output by the time t is described by the expression

and -T, - j x4t) df 10, (4)

25 where C

ZO

35

the intrinsic integration time is constant at the first limit, e is the number of the integrator limit at which the integration, recorded in the first block 7 of the order calculation, ended.

In addition, the input comparator Resolution of the counter 15 permits the counter to count the pulses from a generator of 14 clocks and, by the time t in it and in the second calculator 16, the duration of the measured pulse is formed, which

integrator 6, then if the youngest is 40, you can imagine

the row at the output of the adder 19 is equal to O (i.e., the sum signal at the output of the adder is even), key 11 is turned on, if the low-order bit at the output of adder 19 is 1 (i.e., the signal is odd), key 12 is turned on.

In the initial state, the counters 15 and 18 and the trigger 9 are in the zero state. From the output of the sensor 1, the voltage is O. At the time t, (Fig. 2), the voltage of the sensor 1 begins to increase.

The voltage at the output of the sensor is described by the expression

T. nx 10

MS

45

50

- fj - II l. I y

where n is a binary number in the range of 100.0-1000.5, the counter is recorded 15, and a is the order of the number T in

In block 16, the calculation of the p At the instant of time tj, by closing the first key 3 and the back of the front pulse arriving at the countable trigger 9, its single state is tilted.

The adder 19 produces the sum of the codes entered into it from the outputs of the first block of the order and the second block 16 in the order. U (t) Kg.X (t),. (1) where K is the conversion factor

sensor, X (t) - measured value.

0 can be imagined

T. nx 10

MS

five

0

five

- fj - II l. I y

where n is a binary number in the range of 100.0-1000.5, recorded in the counter 15, and is the order of the number T in the second

block 16, calculating the order. At time tj, the first key 3 is closed, and by the falling edge of the pulse arriving at the counting input of the trigger 9, it is tilted to the one state.

The adder 19 performs the summation of the codes received at its 2 inputs from the outputs of the first order calculation unit and the second order calculation unit 16. The signal from the output of the trigger 9 switches the switching key 5, allows the counter 18 to produce an account

In particular, it acts on its counting input from the generator output of 14 clocks and ylks, and also affects the key management of the DB 20; The signal from the output of this block, depending on the signal arriving at its first input from the output of the adder 19, includes the first switch 11 or the second switch 12. From the voltage input of the reference voltage 1C, the voltage U is fed to the input of the integrator 13. The output voltage integrator 13 is changed by law

 .one

. II

P.

i

dt

s

wl

e s /,

X 10

with

R

 ten

(five)

- constant integration integrator time 13. Moreover, if the second key II is open, then C 0, if the third key 1 is open: then C 1.

The voltage U is fed to the input to: the driver 4 and through the switching key 5 to the analog input of the digital-to-analog converter. The output of the UJUI 17 voltage is described by the expression

and,. „„ 7 r-TUL t. X 10. (6)

  (- “i At time t (FIG. 2), when the voltage at the output of the multi-range -G | O integrator 6 becomes equal to the voltage at the output of the D / A converter 17, the fusion element 8 will reset trigger 9 to zero. For this time point d considering expressions 4 and 6, equality is true

% K5 f X (t) dt X 1 about I ys-Uon t X

(7)

from here

10-%

i4

t2

- € 4cl

X2 (t) dtX10, (8)

IrlliisJ

; P

TH is the time interval of the transformation t. 0-t proportional to the measured value

X2 (t) dt X 10

(9)

where K is the conversion factor

... To L1

According to expression (9), in the counter: 18 after the conversion, a number code is stored that is proportional to the mantissa of the measured rms value

five

0-

five

0 5

0

five

0

five

The pulse, and the order of this value is formed at the output of the adder 19, the division by 2 of this value according to the exponent) (9) is carried out by rejecting the least significant bit of the code value. Using the value C, the conversion of the exponent to an even value is performed. Figure 2 also shows the process of measuring the rms value when the value (-1 + d) in expression (8) is an odd number.

Claims (1)

Invention Formula Measuring the rms value of the voltage of a single random pulse and the duration of the sensor, quad, comparison element, dividing unit, integrator, characterized in that, in order to expand functional capabilities. it introduced a comparator, trigger, two counters, digital-analog. converter, multi-limit integrator, switching key, voltage source, pulse generator, two order calculation blocks, two keys, adder and key control block, the comparator input is connected to the sensor output, and the output is from the trigger input input The resolution of the first counter and the control input of the first key, whose input 11 is connected to the output of the sensor, and the output is combined with the output of the first integrator and connected to the input of the quad, the output of which is connected to the common switch key, the disconnecting contact of which is connected to the input of the multidirectional integrator, the closing contact with the analog input of the digital-to-analog converter whose digital inputs are connected to the outputs of the first counter, and the control switching input of the key is combined with the input of the second counter, the first input of the key management unit and connected to direct output of the trigger, the first input of which Reset is connected to the output of the reference element, one input of which is connected to the output of the digital-to-analog converter, and v swarm - yield mnogopredelnogo integrator and the input of the first calculating unit -por order ;, whose first output is connected to a control input 1c tsemu integrator, and the second to the first input of the adder, the lower bit of the output of which is connected to the second input of the control unit with keys, and the second input to the first output of the second calculation unit, the input of which is connected to the output Overflow of the first counter, and the second output to the input The HOBjca of the first counter, the counting counter of which is combined with the counting input of the second counter and connected to the output Out one Out in 2 clock generator and inputs Reset counters are combined with the second input Reset trigger and connected to the Reset bus, while the first and second outputs of the key management unit are connected respectively to the control inputs of the second and third keys, the inputs of which are combined and connected to the source of the reference voltage and outputs to the inputs of the first integrator. / :: / V l