CN2107023U - Power frequency parameter measuring apparatus - Google Patents
Power frequency parameter measuring apparatus Download PDFInfo
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- CN2107023U CN2107023U CN 91229525 CN91229525U CN2107023U CN 2107023 U CN2107023 U CN 2107023U CN 91229525 CN91229525 CN 91229525 CN 91229525 U CN91229525 U CN 91229525U CN 2107023 U CN2107023 U CN 2107023U
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Abstract
An electric power frequency parameter measuring apparatus is improved on the present basic of the digital power meter with a current/voltage changer, a voltage/current changer, a direct current difference amplifier and a plurality of input select switches. The electric power frequency parameter measuring apparatus has multi-functions and can measure voltage, electric current and power. The utility model has the advantages of high precision, low cost, small size, and portability.
Description
The utility model belongs to electric power surveying instrument technical field.
The digital power meter of existing power, have precision height (being better than 0.05 grade), volume advantage little, easy to carry, can be used for the laboratory calibrates as standard scale, also can be used for on-the-spot actual measurement, blemish in an otherwise perfect thing be to measure average power, can not satisfy the actual needs of measuring voltage, electric current.And having the multi-function power table of measuring multiple parameter, Dian Lu Complex is assorted, cost is high, volume is big, is not easy to again carry.
The purpose of this utility model is to provide a kind of electric power power frequency parameter measurement instrument, can measure power, voltage, electric current, and has precision height, cost is low, volume is little, easy to carry advantage.
Basic design of the present utility model is: on the basis of existing digital power meter, increased the current/voltage transducer, voltage/current transducer, direct current differential amplifier, voltage comparator input selector switch, the modulator input selector switch, the triangular-wave generator input selector switch, the connection Guan Department of appropriate change primary circuit has realized a-table-multi-purpose.
Specified below in conjunction with drawings and Examples.
Fig. 1 is existing digital power meter circuit block diagram.
The circuit block diagram of the power frequency parameter measuring instrument that Fig. 2 provides for the utility model.
Fig. 3 is the current/voltage converter circuit schematic diagram of power frequency parameter measuring instrument.
Fig. 4 is the voltage/current converter circuit schematic diagram of power frequency parameter measuring instrument.
Fig. 5 is the direct current differential amplifier circuit schematic diagram of power frequency parameter measuring instrument.
In Fig. 1,1 is that voltage input end, 2 is that current input terminal, 3 is that voltage transformer (VT), 4 is that current transformer, 5 is that voltage comparator, 6 is that modulator, 7 is that triangular-wave generator, 8 is that filtering and impedance transformer, 9 are that canonical reference voltage generator, 10 is that analog/digital (A/D) transducer, 11 is a digital indicator.When measuring power, voltage U and electric current I are imported from voltage input end 1 and current input terminal 2 respectively, become small-signal U1 and the I1 that is directly proportional with U and I through mutual inductor 3 and 4, respectively input voltage comparer 5 and modulator 6.The triangular wave U3 that U1 and triangular-wave generator 7 produce compares in voltage comparator 5, Shu Chu Mai Red voltage U 2, the frequency of U2 is identical with U3, the dutycycle of U2 is directly proportional with the amplitude of U1, be inversely proportional to the amplitude of U3, and the amplitude of U3 is directly proportional with the value of the DC reference voltage U4 of canonical reference voltage generator 9 generations, thereby the amplitude of the dutycycle of U2 and U4 is inversely proportional to.Because U4 is constant, thereby the dutycycle of U2 is to be determined by the amplitude of U1.Modulator 6 is equivalent to a current switch, and controlled by U2 switching time, and the width of the current impulse I2 of its output is by the modulation of U2 duty of ratio, and amplitude is determined by I1.
We represent the instantaneous value of corresponding electric current I, voltage U with lowercase i, u, and then i2 has represented iu, i.e. the instantaneous power of institute's slowdown monitoring circuit.I2 becomes DC current I3 through filtering and impedance transformer 8, be equivalent to I2 has been carried out on average time T, thereby I3 has represented the average power of institute's slowdown monitoring circuit, I3 becomes DC voltage U5 through the output sample resistance of transducer 8, U5 has also represented the average power of institute's slowdown monitoring circuit, become digital signal through A/D transducer 10, deliver to digital indicator 11 and show.
Above conclusion can be expressed as follows with mathematical expression: the average power R α U5 of institute's slowdown monitoring circuit, i.e. U5=K 1/ (T) S
T OIudt(1), (K is than routine Department number), and K α 1/ (U4), u α u1, i α i1, U4 is a constant, so variable U5=K1 1/ (U4) 1/ (T) S that is changed to of (1) formula
T OU1i1dt(2) (K1 is a Bi Li Department number).
In Fig. 2,1-11 is identical with Fig. 1, increased the current/voltage gearbox 12 that input is connected with current transformer 4 outputs, the voltage/current transducer 13 that input is connected with voltage transformer (VT) 3 outputs, the direct current differential amplifier 14 that input is connected with filtering and impedance transformer 8 outputs.An input end of voltage comparator 5 connects the back contact K1-1 of the input selector switch K1 of voltage comparator 5, and the output of voltage transformer (VT) 3 connects the selection contact K1-2 of K1, and the output of transducer 12 connects the selection contact K1-3 of K1.An input end of modulator 6 connects the back contact K2-1 of the input selector switch K2 of modulator 6, and the output of transducer 13 connects the selection contact K2-2 of K2, and the output of current transformer 4 connects the selection contact K2-3 of K2.The input end of triangular-wave generator 7 connects the back contact K3-1 of the input selector switch K3 of triangular-wave generator 7, and canonical reference voltage is sent out the selection contact K3-2 of the output connection K3 of device 9, and the output of direct current differential amplifier 14 connects the selection contact K3-3 of K3.
When measuring power, K1-1 and K1-2 are connected, K2-1 and K2-3 connect, K3-1 and K3-2 connection, this and the electric principle of digital power meter (Fig. 1) are identical.
When measuring electric current, K1-1 and K1-3 are connected, K2-1 and K2-3 connect, and K3-1 and K3-3 connect, and electric current I to be measured is from current input terminal 2 inputs.Compare with Fig. 1 (during power scale), just with the output voltage U 7 of transducer 12 U1 that replaced, with the output voltage U 6 of direct current amplifier 14 U4 that replaced, voltage input end 1 becomes open circuit, and U6 U5, U7 I1, so can replace U4 with U5, I1 replaces U1 substitution (2) formula, Bi Li Department is counted the corresponding adjustment of K1 change K2 into, obtain U5=K2 1/ (T) 1/ (U5) S
T OI1i1dt can get U5=through arrangement
, i.e. U5 α I1 and represented the effective value of I1, and I1 I are so U5 has also represented the effective value of I.
When measuring voltage, K1-1 and K1-2 are connected, K2-1 and K2-2 connect, and K3-1 and K3-3 connect, and voltage U to be measured is from voltage input end 1 input.Compare with Fig. 1 (during power scale), just with the transducer 13 output current I4 I1 that replaced, with the output voltage U 6 of the direct current amplifier I4 U4 that replaced, current input terminal 2 open circuits, and U6 α U5, I4 α U1, so available U5 replaces U4, U1 replaces I1, and substitution (2) formula is counted K1 with Bi Li Department and is changed to K3 and obtains U5=K3 1/ (T) 1/ (U5) S
T OU1u1dt is through arrangement, U5=
, i.e. U5 α U1, and represented the effective value of U1, and U1 α U, so U5 has also represented the effective value of U.
In Fig. 3, current/voltage transducer 12 is by operational amplifier IC1, and the follower that IC2 forms, proportional amplifier IC3, ratio are adjusted resistance R 2, R3, R4, R5 formation.Electric current I to be measured is through current transformer 4 output current I1, delivers to through sample resistance R1 and selects contact K2-3, delivers to the input end of modulator 6 when measuring electric current and power with back contact K2-1 connection.The R1 two ends connect the positive input terminal of IC1 and IC2 respectively, and the output terminal of IC1 and IC2 is connected negative input end separately respectively, and receive the positive and negative input end of IC3 respectively through R2, R3.The output terminal of IC3 connects the positive input terminal of IC3 through R4, and connects and select contact K1-3, when measuring electric current and back contact K1-1 connect, IC3 output voltage U 7 is delivered to the input end of voltage comparator 5.The IC3 negative input end is through R5 ground connection.
Electric current I to be measured becomes I1 through current transformer 4, the I1 ac voltage signal that R1 takes out of flowing through, and through follower IC1, IC2, the ratio of determining according to R2 and R4, R3 and R5 is sent into IC3 and is carried out the ratio amplification, and realization I1 is to the conversion of U7.But IC1, IC2 Mining operational amplifier LM301, IC3 can use OP07, the desirable 1K of R2 and R3, the desirable 7K of R4 and R5, K1 and K3 can select analog switch CD4053 for use.
In Fig. 4, current-limiting resistance R6, sample resistance R7, current transformer N, follower IC4 form voltage transformer (VT) 3.Voltage/current transducer 13 is made of alteration switch K4, voltage U to be measured is added on the elementary of current transformer N through R6, on R7, become voltage U 1 through mutual inductor N conversion, output to selection contact K1-2 through follower IC4, when measuring power and voltage, connect the input end of delivering to voltage comparator 5 with back contact K1-1.U1 forms electric current I 4 through R7 and delivers to selection contact K4-3 and K2-2, and K4 and K2 switch keep synchronously.When measuring voltage, K2-2 and back contact K2-1 connect, and K4-2 and back contact K4-1 connect, and U1, I4 are through the secondary formation loop of R7, K4, K2, modulator 6 and mutual inductor N, and I4 delivers to the input end of modulator 6.When measuring electric current and power, back contact K2-1 disconnects with selecting contact K2-2, connects with K2-3, back contact K4-1 disconnects with selecting contact K4-2, connect with K4-3, U1, I4 are through the secondary formation loop of R7, K4 and mutual inductor N, and I4 is input modulator 6 no longer.K4-2 is an idle contact, and K4-1 is connected with a secondary end and the modulator 6 of mutual inductor N, and K4-3 is connected with K2-2, and is connected with the secondary other end of mutual inductor N through R7, and the R7 two ends are connected with IC4 two input ends.K4 can select analog switch CD4053 for use.
In Fig. 5, direct current differential amplifier 14 is by operational amplifier IC5, IC6, IC7, and ratio is adjusted resistance R 9, R10, R11, R12 composition; The DC voltage U5 that takes out from the output resistance R8 two ends of filtering and impedance transformer 8, the positive input terminal of input follower IC5, IC6, the output terminal of IC5, IC6 connects negative input end separately respectively, and receive the positive and negative input end of IC7 respectively through R9, R10, the output terminal of IC7 is connected with the positive input terminal of IC7 through R11, and connects selection contact K3-3.When measuring voltage and voltage, select contact K3-3 and back contact K3-1 to connect, the output voltage U 6 of IC7 is through K3 input triangular-wave generator 7; The negative input end of IC7 is through R12 ground connection.
The enlargement factor of amplifier 14 is by the ratio decision of R9 and R11, R10 and R12, be to design according to transducer 12 and 13 De Department numbers, R9 and R10 get 1K in this example, and R11 and R12 get 6.2K, IC5, IC6, IC7 can use operational amplifier OP07 or LM308, and K3 can select analog switch CD4053 for use.
The power frequency parameter measuring apparatus that the utility model provides has the following advantages:
1, has the several functions of measuring power-frequency voltage, electric current, power, realize a-table-multi-purpose.
2, precision height (can reach 0.05 grade), cost is low, ratio of performance to price height.
3, volume is little, and is easy to carry.
Can make power-frequency voltage table, the use of power current table separately.
Claims (4)
1, a kind of power frequency parameter measuring instrument, by ac voltage input 1, alternating current input end 2, voltage transformer (VT) 3, current transformer 4, voltage comparator 5, modulator 6, triangular-wave generator 7, filtering and impedance transformer 8, canonical reference voltage generator 9, analog/digital (A/D) transducer 10, digital indicator 11 is formed, it is characterized in that, has the current/voltage transducer 12 that input is connected with current transformer 4 outputs, the voltage/current transducer 13 that input is connected with voltage transformer (VT) 3 outputs, the direct current differential amplifier 14 that input is connected with filtering and impedance transformer 8 outputs, the input selector switch K1 of voltage comparator 5, the input selector switch K2 of modulator 6, the input selector switch K3 of triangular-wave generator 7; An input end of voltage comparator 5 connects the back contact K1-1 of K1, and the output of voltage transformer (VT) 3 connects selects contact K1-2, the output of transducer 12 to connect selection contact K1-3; An input end of modulator 6 connects the back contact K2-1 of K2, and the output of transducer 13 connects selects contact K2-2, the output of current transformer 4 to connect selection contact K2-3; The input end of triangular-wave generator connects the back contact K3-1 of K3, and the output of reference voltage generator 9 connects selects contact K3-2, the output of direct current differential amplifier 14 to connect selection contact K3-3.
2, power frequency parameter measuring instrument as claimed in claim 1 is characterized in that, the follower that current/voltage transducer 12 is made up of operational amplifier IC1, IC2, proportional amplifier IC3, ratio adjustment resistance R 2, R3, R4, R5 constitute; Electric current I to be measured is through current transformer 4 output current I1, delivers to through sample resistance R1 and selects contact K2-3, delivers to the input end of modulator 6 when measuring electric current and power with back contact K2-1 connection; The R1 two ends connect the positive input terminal of IC1 and IC2 respectively, and the output terminal of IC1 and IC2 is connected negative input end separately respectively, and connect the positive and negative input end of IC3 respectively through R2, R3; The output terminal of IC3 connects the positive input terminal of IC3 through R4, and connects and select contact K1-3, and with back contact K1-1 connection, IC3 output voltage U 7 is delivered to the input end of voltage comparator 5 when measuring electric current; The IC3 negative input end is through R5 ground connection.
3, power frequency parameter measuring instrument as claimed in claim 1, it is characterized in that, voltage/current transducer 13 is made up of alteration switch K4, back contact K4-1 is connected with a secondary end and the modulator 6 of the current transformer N of voltage transformer (VT) 3, K4-3 is connected with K2-2, and be connected with the secondary other end of mutual inductor N through sample resistance R7, the R7 two ends are connected with IC4 two input ends; Voltage to be measured becomes voltage U 1 through voltage transformer (VT) 3, and U1 forms electric current I 4 through sample resistance R7 and delivers to selection contact K4-3 and K2-2, and K4 and K2 switch keep synchronously; When measuring voltage, K2-2 and back contact K2-1 connect, and K4-2 and back contact K4-1 connect, and U1, I4 are through the secondary formation loop of the current transformer N of R7, K4, K2, modulator 6 and voltage transformer (VT) 3, and I4 delivers to modulator 6 input ends; When measuring power and electric current, back contact K2-1 disconnects with selecting contact K2-2, connects with K2-3, back contact K4-1 disconnects with selecting contact K4-2, connect with K4-3, U1, I4 are through the secondary formation loop of R7, K4 and current transformer N, and I4 is input modulator 6 no longer.
4, power frequency parameter measuring instrument as claimed in claim 1 is characterized in that, direct current differential amplifier 14 is made up of operational amplifier IC5, IC6, IC7, ratio adjustment resistance R 9, R10, R11, R12; The DC voltage U5 that takes out from the output resistance R8 two ends of filtering and impedance transformer 8, the positive input terminal of input follower IC5, IC6, the output terminal of IC5, IC6 connects negative input end separately respectively, and receive the positive and negative input end of IC7 respectively through R9, R10, the output terminal of IC7 is connected with the positive input terminal of IC7 through R11, and connects selection contact K3-3; When measuring electric current and voltage, select contact K3-3 and back contact K3-1 to connect, the output voltage U 6 of IC7 is through K3 input triangular-wave generator 7; The negative input end of IC7 is through R12 ground connection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 91229525 CN2107023U (en) | 1991-12-02 | 1991-12-02 | Power frequency parameter measuring apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 91229525 CN2107023U (en) | 1991-12-02 | 1991-12-02 | Power frequency parameter measuring apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2107023U true CN2107023U (en) | 1992-06-10 |
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ID=4935008
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 91229525 Granted CN2107023U (en) | 1991-12-02 | 1991-12-02 | Power frequency parameter measuring apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2107023U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1330965C (en) * | 2005-06-24 | 2007-08-08 | 东南大学 | Oscilloscope condition triggering method based on finit state machine |
| CN1330969C (en) * | 2004-08-25 | 2007-08-08 | 江苏省电力公司南京供电公司 | Power frequency parameter tester and testing method for high tension transmission line |
| CN100422749C (en) * | 2003-02-12 | 2008-10-01 | Iad信息自动化及数据处理有限公司 | Measuring system comprising an intelligent sensor head and having a reduced power consumption for medium-voltage or high-voltage systems or in mining, and method therefor |
| CN108365759A (en) * | 2018-03-30 | 2018-08-03 | 佛山科学技术学院 | A kind of current/voltage converter circuit |
-
1991
- 1991-12-02 CN CN 91229525 patent/CN2107023U/en active Granted
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100422749C (en) * | 2003-02-12 | 2008-10-01 | Iad信息自动化及数据处理有限公司 | Measuring system comprising an intelligent sensor head and having a reduced power consumption for medium-voltage or high-voltage systems or in mining, and method therefor |
| CN1330969C (en) * | 2004-08-25 | 2007-08-08 | 江苏省电力公司南京供电公司 | Power frequency parameter tester and testing method for high tension transmission line |
| CN1330965C (en) * | 2005-06-24 | 2007-08-08 | 东南大学 | Oscilloscope condition triggering method based on finit state machine |
| CN108365759A (en) * | 2018-03-30 | 2018-08-03 | 佛山科学技术学院 | A kind of current/voltage converter circuit |
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| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |