CN202443051U

CN202443051U - Voltage measuring instrument

Info

Publication number: CN202443051U
Application number: CN2011205738235U
Authority: CN
Inventors: 孙笑声
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-12-30
Filing date: 2011-12-30
Publication date: 2012-09-19
Anticipated expiration: 2021-12-30

Abstract

A voltage measuring instrument is used for measuring DC voltage. In the measuring instrument, a first stepping disc is a measuring disc composed of 23 1 ohm resistors; a second stepping disc is composed of a measuring disc and a replacing disc, wherein the measuring disc is composed of 10 0.1 ohm resistors; a third stepping disc is also composed of a measuring disc and a replacing disc, wherein the measuring disc is composed of 10 0.1 ohm resistors; contacts of a forth stepping disc and a fifth stepping disc are connected with corresponding contacts of the measuring disc of the third stepping disc, thus the forth stepping disc and the fifth stepping disc are not provided with resistors, a special connecting wire is adopted in the second stepping disc, thus voltage of a lead wire resistor inside the voltage measuring instrument is almost reduced to zero, and zero potential influences can be omitted when using the voltage measuring instrument to measure.

Description

Pressure measuring instrument

Technical field

The utility model relates to the instrument that DC voltage is measured.

Background technology

Current for the pressure measuring instrument that five step discs are arranged, in the connection between five step discs, telophragma generally adopts switch to switch, and so just produces the variation of contact resistance, brings restriction to resolution.In order to overcome this problem, generally adopt big brush with the increase contact area, and adopt silver-carbon/carbon-copper composite material; Application number 200810121910.X discloses the new method that the pressure measuring instrument that five step discs are arranged solves the switch contact resistance variation; Its five step discs all are made up of measuring disk and replacement dish; Do not contain bracket panel, on each measuring disk and the replacement dish resistance is arranged all, measuring disk and replacement dish on its five step discs have been formed bridge circuit in circuit; Its maximum defect is that error is not independent; In case the measuring disk point error of indication surpasses allowed band, just can't problem identificatioin come from which resistance, this makes troubles to identifying with maintenance.

The utility model content

The purpose of the utility model is a kind of pressure measuring instrument that five step discs are arranged of design, and it does not adopt bridge circuit, and error can be independent like this, and latter two step disc has only measuring disk, do not have resistance on the measuring disk, and this can reduce cost, and reduces the instrument volume.

The technical scheme of the utility model is taked like this: from the anodal terminal of the external 3V working power of pressure measuring instrument E through 44 Ω resistance R ₀, the adjustable resistance R that constitutes by 21 3 Ω resistance _P1, the adjustable resistance R of range of adjustment between 0～3.2 Ω _P2, the adjustable resistance R of range of adjustment between 0～0.15 Ω _P3, the negative pole terminal of getting back to external 3V working power E through five step discs is again formed pressure measuring instrument work loop; External standard cell E _NAnodal terminal is set up resistance R through the double-point double-throw switch K that is connected to galvanometer G between two normally closed contacts to 1018 Ω ₁, again through constituting temperature compensation dish W to external standard cell E by 20 0.05 Ω resistance _NThe negative pole terminal is formed the pressure measuring instrument standard loop; Be used to connect measured " U _X" two terminals, anodal terminal through five measuring disk after, form the pressure measuring instrument equalizing network through the double-point double-throw switch K that is connected to galvanometer G between two normally closed contacts to the negative pole terminal again; It is characterized in that first step disc has measuring disk I; It has 0,1,2 ... 23 totally 24 gears; Except that the 0th, the 1st contact; All the other respectively keep off between the contact and to connect one of 1 Ω resistance, second step disc by have 0,1,2 ... 10 totally 11 gears measuring disk II with have 0,1,2 ... The 10 replacement dish II ' compositions of totally 11 gears, measuring disk II is except that the 0th, the 1st contact; Measuring disk II respectively keeps off with replacement dish II ' and is connected one of 0.1 Ω resistance between the contact; Measuring disk III that the 3rd step disc is made up of 10 0.1 Ω resistance and the replacement dish III ' that is made up of 10 0.1 Ω resistance form, the corresponding contact connection in each contact on the measuring disk V of the measuring disk IV of the 4th step disc, the 5th step disc and the 3rd step disc on the measuring disk, adjustable resistance R _P3Electronegative potential one end be circuit node C; Be divided into two-way behind the electric current process node C: the one tunnel connects the Metal Contact ring of replacement dish II ' in second step disc; Replacement dish II ' the 10th contact connects the 23rd contact of measuring disk I; The 1st contact of measuring disk I is through connecting the Metal Contact ring of measuring disk II behind one 1 Ω resistance, the 0th contact of measuring disk I connects the 10th contact of measuring disk II, and the 0th contact tie point of the 0th contact of measuring disk II and measuring disk III is circuit node A; The 1st contact of measuring disk II is through CC node A behind one 0.1 Ω resistance, and the Metal Contact ring of the measuring disk V of the 5th step disc is through 100K Ω resistance R ₄The Metal Contact ring of back and measuring disk IV is through 10K Ω resistance R ₅After be connected in circuit node B, the 10th contact of replacement dish III ' is through 999 Ω resistance R ₆B is connected with circuit node, and circuit node A is through 112.486 Ω resistance R ₃The CC Node B, Node B is divided into two-way: the one tunnel through 1018 Ω setting resistance R ₁20 the 0.05 Ω resistance of process temperature compensation dish W are to circuit node C again, and another road is through 113.2222 Ω resistance R ₂C is connected with circuit node, and node C connects the negative pole terminal of the external 3V working power of pressure measuring instrument E; Be used to connect measured " U _X" two measure terminals, anodal terminal is connected with the Metal Contact ring of measuring disk I, the negative pole terminal is connected with the 10th contact of measuring disk III after through the double-point double-throw switch K that is connected to galvanometer G between two normally closed contacts.

Through above technical scheme, first step disc need not the replacement dish, and the 4th, the 5th step disc is replacement dish not all; And four, all there is not resistance on the measuring disk of the 5th step disc; Five step disc errors are independent, and the error that back two dish synchronised forward (FWD)s come is consistent, and this brings convenience for debugging and maintenance; Also make pressure measuring instrument simple in structure, volume-diminished, thus reduced production cost; When five measuring disk resets of pressure measuring instrument; The internal wiring combined potential of pressure measuring instrument is an A point current potential; Some current potentials are " 0 "; So the zero potential of this pressure measuring instrument is very little, the thermoelectrical potential of back three several μ V of each branch road of step disc all is connected in the 1V voltage drop, so thermoelectrical potential is to " U _X" two measure the terminals influence and can ignore;

Description of drawings

Accompanying drawing is the utility model schematic circuit.

In Fig. 1; The resistance of measuring disk II and last 10 * 0.1 Ω of replacement dish II ' in second step disc, each is made up of expression measuring disk II and replacement dish II ' the resistance of 10 0.1 Ω, in like manner last 23 * 1 Ω of measuring disk I; Expression measuring disk I form adjustable resistance R by 23 1 Ω resistance _P1The expression adjustable resistance R of last 21 * 3 Ω _P1Constitute by 21 3 Ω resistance.

In Fig. 1, thick black line is represented the Metal Contact ring on step disc and the temperature compensation dish, and hollow small circle is represented hard contact, and four-headed arrow is represented metallic brush.

Embodiment

Among Fig. 1, measuring disk II is identical with the resistance value of each stepping of replacement dish II ' in second step disc, all is 0.1 Ω, and the measuring disk II resistance that every stepping increases in circuit equals the resistance that the every stepping of replacement dish II ' reduces, so total resistance is constant in the circuit; The 3rd step disc comes holding circuit always to hinder invariance principle with second step disc with measuring disk III and replacement dish III '.The pressure measuring instrument working current is designed to 10mA; Pressure measuring instrument 10mA working current is divided into four the tunnel: the one tunnel through measuring disk IV through first, second step disc behind node A; One the tunnel through measuring disk V, and another road is through the 3rd step disc, and one the tunnel through 112.486 Ω resistance R again ₃, four road electric currents meet at Node B.Remove through resistance R ₃Outside the branch road, each branch road resistance ratio: measuring disk V: measuring disk IV between node A, the Node B: the 3rd step disc=100: 10: 1, so, remove and flow through resistance R ₃Outside the branch road, flow through that each branch current ratio is between node A, the Node B: measuring disk V: measuring disk IV: the 3rd step disc=1: 10: 100, remove resistance R ₃Outside the branch road, resistance is 100K Ω/111 between node A, the Node B, lets the total current that flows through measuring disk V, measuring disk IV and the 3rd step disc be 1.11mA, flows through resistance R ₃Electric current be 8.89mA, then 8.89mA * R ₃=100K Ω/111 * 1.11mA, resistance R ₃=112.486 Ω.Pressure measuring instrument 10mA working current is through resistance R ₃Shunting makes that flowing through measuring disk V electric current is 0.01mA, and measuring disk IV electric current is 0.1mA, and the 3rd step disc electric current is 1mA; When each step disc is put different indicating value between node A and the Node B resistance change, resistance is used resistance R between node A and the Node B _ABExpression, each step disc resistance variable is X, then 1/R _AB≈ 1/ (100K Ω+and X)+1/ (10K Ω+X)+1/1K Ω+889/100K Ω

Both sides differentiate: (1/R _AB{ 1/ (100K+X)+1/ (10K+X)+1/ (1000)+889/100K} ' of) '=

-R _AB′/R _AB ²＝{-1/(100K+X) ²-1/(10K+X) ²+0+0}

R _AB′＝{1/(100K+X) ²+1/(10K+X) ²}R _AB ²

R _ABDerivative be on the occasion of, so when each step disc resistance variable increases, total resistance R between node A and the Node B _ABIncrease.Resistance minimum between node A and Node B during each step disc reset indicating value, at this moment resistance is 100 Ω between node A, the B, resistance R between node A and Node B when each step disc is put " 10 " indicating value _ABMaximum, at this moment resistance R between node A, the B _ABBe 100.002 Ω, than minimum indicating value big 100,000/, therefore, when the pressure measuring instrument precision was not higher than 2/10000ths, no matter what indicating value each step disc put, change in resistance can be ignored between node A, the B.

After the working current standardization, the I measuring disk is thrown n ₁, the II measuring disk is thrown n ₂, the III measuring disk is thrown n ₃, the IV measuring disk is thrown n ₄, the V measuring disk is thrown n ₅, K switch is thrown to the left side, is positioned at this moment that voltage is between two terminals of measurement:

U _X＝10×n ₁+10×0.1n ₂+1×0.1n ₃+0.1×0.1n ₄+0.01×0.1n ₅(mv)

＝10n ₁+n ₂+0.1n ₃+0.01n ₄+0.001n ₅(mv)

Saturated standard cell E _NElectromotive force is about 1.0186V, 1 ℃ of the every increase of temperature, and output voltage reduces 40 μ V approximately, sets up resistance R from 1018 Ω ₈, adding the total resistance of 20 0.05 Ω resistance formation temperature compensation dish W is 1019 Ω, resistance R ₂Resistance 1019 Ω 1/9, therefore flow through resistance R ₂Electric current be 9mA, flow through 1018 Ω and set up resistance R ₈The electric current that reaches temperature compensation dish W is 1mA, and 1018 Ω set up resistance R ₈Last voltage 1.018V, the every stepping bucking voltage 50 μ V of temperature compensation dish W when double-point double-throw switch K throws to the right, can carry out temperature compensation to external saturated standard cell.

The standard operation electric current is to confirm like this: external saturated standard cell is annual to be identified to provincial metrological service; Obtain room temperature exact value in the time of 20 ℃; According to thermometer displayed value on the saturated standard cell of 0.1 degree resolution; The contrast form can be known the electromotive force of saturated standard cell, and perhaps every rising deducts 40 μ V for 1 ℃ to be estimated, and is consistent with the electromotive force value of saturated standard cell according to value on the electromotive force adjusting temperature compensation dish of saturated standard cell; Double-point double-throw switch K is thrown to the right, through regulating adjustable resistance R _P1, adjustable resistance R _P2, adjustable resistance R _P3, make galvanometer G nulling, at this moment working current is 10mA with regard to standardization.

The voltage-measuring equipment WV is 3V, because the every joint stable electrical of dry cell kinetic potential between 1.4V～1.65V, all can be adjusted to standard state to the voltage-measuring equipment working current for realizing supply voltage at 1.35V～1.65V, gets fixed resistance R ₀=44 Ω, adjustable resistance RP ₁=21 * 3 Ω, adjustable resistance RP ₂Be 0～3.2 Ω, adjustable resistance R _P3Be 0～0.15 Ω, being together in series with two groups of A-batteries so just can be used as external 3V working power, also can use the work of external 3V stabilized voltage supply.

Claims

1. pressure measuring instrument, from the anodal terminal of the external 3V working power of pressure measuring instrument E through 44 Ω resistance R ₀, the adjustable resistance R that constitutes by 21 3 Ω resistance _P1, the adjustable resistance R of range of adjustment between 0～3.2 Ω _P2, the adjustable resistance R of range of adjustment between 0～0.15 Ω _P3, the negative pole terminal of getting back to external 3V working power E through five step discs is again formed pressure measuring instrument work loop; External standard cell E _NAnodal terminal is set up resistance R through the double-point double-throw switch K that is connected to galvanometer G between two normally closed contacts to 1018 Ω ₁, again through constituting temperature compensation dish W to external standard cell E by 20 0.05 Ω resistance _NThe negative pole terminal is formed the pressure measuring instrument standard loop; Be used to connect measured " U _X" two terminals, anodal terminal through five measuring disk after, form the pressure measuring instrument equalizing network through the double-point double-throw switch K that is connected to galvanometer G between two normally closed contacts to the negative pole terminal again; It is characterized in that first step disc has measuring disk I; It has 0,1,2 ... 23 totally 24 gears; Except that the 0th, the 1st contact; All the other respectively keep off between the contact and to connect one of 1 Ω resistance, second step disc by have 0,1,2 ... 10 totally 11 gears measuring disk II with have 0,1,2 ... The 10 replacement dish II ' compositions of totally 11 gears, measuring disk II is except that the 0th, the 1st contact; Measuring disk II respectively keeps off with replacement dish II ' and is connected one of 0.1 Ω resistance between the contact; Measuring disk III that the 3rd step disc is made up of 10 0.1 Ω resistance and the replacement dish III ' that is made up of 10 0.1 Ω resistance form, the corresponding contact connection in each contact on the measuring disk V of the measuring disk IV of the 4th step disc, the 5th step disc and the 3rd step disc on the measuring disk, adjustable resistance R _P3Electronegative potential one end be circuit node C; Be divided into two-way behind the electric current process node C: the one tunnel connects the Metal Contact ring of replacement dish II ' in second step disc; Replacement dish II ' the 10th contact connects the 23rd contact of measuring disk I; The 1st contact of measuring disk I is through connecting the Metal Contact ring of measuring disk II behind one 1 Ω resistance, the 0th contact of measuring disk I connects the 10th contact of measuring disk II, and the 0th contact tie point of the 0th contact of measuring disk II and measuring disk III is circuit node A; The 1st contact of measuring disk II is through CC node A behind one 0.1 Ω resistance, and the Metal Contact ring of the measuring disk V of the 5th step disc is through 100K Ω resistance R ₄The Metal Contact ring of back and measuring disk IV is through 10K Ω resistance R ₅After be connected in circuit node B, the 10th contact of replacement dish III ' is through 999 Ω resistance R ₆B is connected with circuit node, and circuit node A is through 112.486 Ω resistance R ₃The CC Node B, Node B is divided into two-way: the one tunnel through 1018 Ω setting resistance R ₁20 the 0.05 Ω resistance of process temperature compensation dish W are to circuit node C again, and another road is through 113.2222 Ω resistance R ₂C is connected with circuit node, and node C connects the negative pole terminal of the external 3V working power of pressure measuring instrument E; Be used to connect measured " U _X" two measure terminals, anodal terminal is connected with the Metal Contact ring of measuring disk I, the negative pole terminal is connected with the 10th contact of measuring disk III after through the double-point double-throw switch K that is connected to galvanometer G between two normally closed contacts.