CN101063694B

CN101063694B - Voltage measurement instrument

Info

Publication number: CN101063694B
Application number: CN2007100690007A
Authority: CN
Inventors: 张春雷; 方李
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-05-29
Filing date: 2007-05-29
Publication date: 2010-06-02
Anticipated expiration: 2027-05-29
Also published as: CN101063694A

Abstract

This invention relates to one original voltage measurement meter, which comprises the following parts: first feed disc is composed of one measure panel and two aid panels without resistance; the second feed panel forms measure panel by eleven resistance of 110Omega and forms aid panel by ten resistance of 5Omega; the third feed panel is composed of 10X10Omega test panel and overlap panel; the fourth feed panel each point is connected to relative one in third panel connected by wire not through switch free of impact by various difference and thermal potential.

Description

A kind of novel pressure measuring instrument

Technical field

The present invention relates to the instrument measured to DC voltage.

Background technology

Currently for the potential difference meter for having four measurement disks, in the connection between four measurement disks, telophragma generally using switch switching, thus produces the variation of contact resistance, limitation is brought to resolution ratio.In order to overcome the problem, big brush is typically used to increase contact area, and use silver-copper composite；The potential difference meter that application number 200510062369.6 discloses four measurement disks solves the new method that switch contact resistance is deteriorated, its first, second step disc is respectively made up of Measuring plate with replacement disk, Measuring plate is identical with the resistance on replacement disk, Measuring plate often increases a resistance, replacement disk is reduced by same resistance, its the 3rd, 4th step disc respectively has Measuring plate, the disk that replaces is constituted with bracket panel, because the 3rd step disc is not put at 10, circuit always resistance is change when 4th step disc puts different indicating values, 3rd step disc is put at 10, circuit always hinders constant when 4th step disc puts different indicating values, being removed for this 3rd step disc has Measuring plate, replace outside disk, add bracket panel and put 10 to distinguish step disc and do not put the circuit connection of 10 two kinds of situations, 4th step disc also increases bracket panel, having 10 resistance above, circuit is always hindered constant to be respectively connected to or cut out several resistance.Four measurement disks are connected between two measurement terminals, the brush that step disc is switched is excluded outside measuring loop, switch switching is not present between the resistance on four measurement disks, variation is not just produced yet；15 ° of angles are rotated because potential difference meter step disc switchs each stepping, every layer can be distributed 24 contacts, the Measuring plate of first step disc is 21 contacts with replacement disk, two layers inside and outside needing, every layer has resistance, and internal layer resistance is overproof to make troubles maintenance, Measuring plate, replacement disk and each half storey of bracket panel of 4th step disc, step disc switch is also needed inside and outside two layers, and internal layer also has resistance, and maintenance is also inconvenient.

The content of the invention

The purpose of the present invention is a kind of novel pressure measuring instrument of design, is not switched in the connection of four measurement disks by switching, and the first step disc cancels replacement disk, and the resistance on four step discs is mounted in one layer.

Technical scheme is so taken：Pass through the resistance measurement network that is made up of four step discs, range swithching resistance and range selector from the positive poles of external 15V working powers to 509 Ω setting resistance R_NAnd 0~1 lockable adjustable resistance R of Ω_P3Pass through 0~75 Ω adjustable resistances R again_P2And 20 × 70 Ω adjustable resistance R_P1The negative pole for returning to external 15V working powers constitutes the performance loop of pressure measuring instrument；Normal cell E_NPositive pole is by being connected to galvanometer G double-point double-throw switch K between two normally-closed contacts₂To setting resistance R_NAnd lockable adjustable resistance R_P3Sliding contact, then pass through 75K Ω current-limiting resistances R to normal cell E_NNegative pole constitutes the standard loop of pressure measuring instrument；For connecting measured " U_X" two terminals, positive pole terminal is after four measurement disks, then by being connected to galvanometer G double-point double-throw switch K between two normally-closed contacts₂The compensation loop of pressure measuring instrument is constituted to negative pole terminal；First step disc has Measuring plate I, it has 0~22 totally 23 gears, in addition to being directly connected between 0,1 contact, 100 Ω resistance one is connected between remaining each shelves contact, separately there is bracket panel I ' and bracket panel I "; bracket panel I ' brush is circuit node B with the tie point that bracket panel I " brush is connected with wire, bracket panel I ' 0 contact and bracket panel I " 0 contact are isolated, and remaining all contact is connected with wire；Second step disc is made up of Measuring plate II with bracket panel II ', and Measuring plate II has 0~10 totally 11 gears, and the resistance for having 11 110 Ω above is circlewise connected：1st resistance R₁Weld the 2nd resistance R in one end₂One end, resistance R₂The other end welds the 3rd resistance R₃One end, resistance R₃The other end welds the 4th resistance R₄One end, resistance R₄The other end welds the 5th resistance R₅One end, resistance R₅The other end welds the 6th resistance R₆One end, resistance R₆The other end welds the 7th resistance R₇One end, resistance R₇The other end welds the 8th resistance R₈One end, resistance R₈The other end welds the 9th resistance R₉One end, resistance R₉The other end welds the 10th resistance R₁₀One end, the 10th resistance R₁₀The other end and the 11st resistance R₁₁One end tie point be circuit node C, the 11st resistance R₁₁The other end and the 1st resistance R₁The other end to be connected to 0 contact of Measuring plate in 0 contact of Measuring plate in the 3rd step disc, the 3rd step disc be circuit node D, resistance R₁With resistance R₂Tie point pass through 200 Ω resistance and the 1st contact portion, resistance R₂With resistance R₃Tie point pass through 120 Ω resistance and the 2nd contact portion, resistance R₃With resistance R₄Tie point pass through 60 Ω resistance and the 3rd contact portion, resistance R₄With resistance R₅Tie point pass through 20 Ω resistance and the 4th contact portion, resistance R₅With resistance R₆Tie point and the 5th contact portion, resistance R₆With resistance R₇Tie point and the 6th contact portion, resistance R₇With resistance R₈Tie point pass through 20 Ω resistance and the 7th contact portion, resistance R₈With resistance R₉Tie point pass through 60 Ω resistance and the 8th contact portion, resistance R₉With resistance R₁₀Tie point pass through 120 Ω resistance and the 9th contact portion, resistance R₁₀With resistance R₁₁Tie point pass through 200 Ω resistance and the 10th contact portion, resistance R₁With resistance R₁₁The node D of connection passes through 300 Ω resistance and 0 contact portion, and the bracket panel II ' of the second step disc is above 10 5 Ω resistance；3rd step disc is made up of Measuring plate III with replacement disk III ', is 10 10 Ω resistance on Measuring plate III, is 10 10 Ω resistance on replacement disk III, the brush of Measuring plate III brush and replacement disk III ' is with a piece of metallic brush piece；4th step disc only has Measuring plate IV, its each contact and the corresponding contact portion on Measuring plate III；The contacts of bracket panel II ' the 10th and 700 Ω range swithching resistance R₁₇One end and 70 Ω range swithching resistance R₁₈One end be parallel to node A, the positive pole of the external working power of node A connection pressure measuring instruments, 700 Ω range swithching resistance R₁₇Other end connection range selector K₁Middle K_1-1Layer × 1 range contact, 70 Ω range swithching resistance R₁₈Other end connection range selector K₁Middle K_1-1Layer × 0.1 and × 0.01 range contact, bracket panel II ' 0 contact portion bracket panel I " 0 contact, the other contacts of bracket panel II ' brush connection bracket panel I " in addition to 0 contact, Measuring plate II brush passes through 1900 Ω resistance R₁₂Connecting node B afterwards, other contact portion Measuring plate I 22nd contacts of the bracket panel I ' in addition to 0 contact, Measuring plate I the 0th, 1 contact are connected with node C, and bracket panel I ' 0 contact is connected after 2200 Ω resistance with node D, Measuring plate IV brush series connection 1000k Ω resistance R₁₅Afterwards with 147.25 Ω resistance R₁₆One end tie point be circuit node E, replacement disk III ' the Ω resistance R of the 10th contact series 99950₁₄Connecting node E, 5293.92 Ω resistance R afterwards₁₃One end connecting node D, the other end connecting node E, 147.25 Ω resistance R₁₆The other end be connected to range selector K₁Middle K_1-1Layer × 10 range contacts, range selector K₁Middle K_1-1Layer × 10 range contact and range selector K₁Middle K_1-2Layer × 1 range contact connected with wire, K_1-2Layer × 1 range contact and × 0.1 pass through 630 Ω resistance R between range contact₁₉Connection, K_1-2Layer × 0.1 range contact and × 0.01 pass through 63000 Ω resistance R between range contact₂₀Connection, 5670 Ω resistance R₂₁One end pass through 560.07 Ω resistance R₂₃Connect range selector K₁Middle K_1-3Layer × 0.01 range contact, pass through 560.7 Ω resistance R₂₂Connect range selector K₁Middle K_1-3Layer × 0.1 range contact and with range selector K₁Middle K_1-3Layer × 1 range contact connected with wire, 5670 Ω resistance R₂₁The other end and range selector K₁Middle K_1-3Layer × 10 range contact all with set up resistance R_NHot end connection, range selector K₁In three layers of K_1-1Layer, K_1-2Layer, K_1-3Three normally-closed contacts of layer are connected with wire；For connecting measured " U_X" two measurement terminals, positive pole is connected with Measuring plate I brushes, and negative pole is by double-point double-throw switch K₂Afterwards with Measuring plate III the 10th contact portion.

By above technical scheme, the first step disc, can be mounted in switch nexine all without resistance on two layers of bracket panel without the disk that replaces, and Measuring plate I is mounted in switch outer layer；Second step disc is without the disk that replaces, switch each stepping and rotate 15 ° of angles, each 11 contacts of bracket panel II ' and Measuring plate II of second step disc are distributed in the same layer of switch, resistance is mounted in switch outer layer, three, the 4th step discs are all without bracket panel, resistance can be unloaded and load onto easily, this brings convenience to debugging with maintenance mounted in switch outer layer when resistance is overproof；This makes pressure measuring instrument simple in construction, and volume-diminished also reduces production cost；Have and do not switched on the circuit of part with performance loop in pressure measuring instrument internal compensation loop, so in the absence of variation influence, when pressure measuring instrument four measurement disks reset, the zero potential of pressure measuring instrument is the zero potential of D points, in compensation loop, lead resistance is flowed through in the absence of operating current, so this pressure measuring instrument zero potential very little, without switch switching on circuit due to having part in pressure measuring instrument internal compensation loop and performance loop, so this pressure measuring instrument thermoelectrical potential and variable thermoelectrical potential also very little.

Brief description of the drawings

Fig. 1 is principle of the invention circuit.

Embodiment

In Fig. 1, Measuring plate II is 11 110 end to end resistance rings of Ω between node C and node D, when Measuring plate II puts " 5 " or puts " 6 ", Measuring plate II brush is to being 5 110 Ω resistance and 6 110 Ω resistor coupled in parallel between node D, resistance is 300 Ω to the maximum after parallel connection, Measuring plate II other contacts are all connected to 300 Ω to the resistance value between node D and are defined, and corresponding points are directly connected on 5,6 contacts and resistance ring；When Measuring plate II puts " 4 " or puts " 7 ", Measuring plate II brush is to being 4 110 Ω resistance and 7 110 Ω resistor coupled in parallel between node D, and resistance is 280 Ω after parallel connection, so 4,7 contacts are connected by 20 Ω resistance with corresponding points on resistance ring；When Measuring plate II puts " 3 " or puts " 8 ", Measuring plate II brush is to being 3 110 Ω resistance and 8 110 Ω resistor coupled in parallel between node D, and resistance is 240 Ω after parallel connection, so 3,8 contacts are connected by 60 Ω resistance with corresponding points on resistance ring；When Measuring plate II puts " 2 " or puts " 9 ", Measuring plate II brush is to being 2 110 Ω resistance and 9 110 Ω resistor coupled in parallel between node D, and resistance is 180 Ω after parallel connection, so 2,9 contacts are connected by 120 Ω resistance with corresponding points on resistance ring；When Measuring plate II sets or when putting " 10 ", Measuring plate II brush to being 1 110 Ω resistance and 10 110 Ω resistor coupled in parallel between node D, it is in parallel after resistance be 100 Ω, so 1,10 contacts are connected by 200 Ω resistance with corresponding points on resistance ring；When Measuring plate II resets, Measuring plate II brush is to being the connection of 300 Ω resistance between node D.

First step disc reset, the second step disc put " n " (n=0,1,2,3 ... 10) when, the resistance value between node B and node D is two and is both 2200 Ω resistor coupled in parallel, therefore is 1100 Ω resistance values.

First step disc put " n " (n=0,1,2,3 ... 22), the second step disc reset when, the resistance value between node B and node D is also two 2200 Ω resistor coupled in parallel, therefore is also 1100 Ω resistance values.

When first, second step disc not resets, in addition to the second step disc puts " 10 ", the calculating of the resistance value between node B and node D needs to carry out triangle-Star transformation.

During the second step disc set, the calculating of the resistance value between node B and node D：If resistance (R₂+R₃+…+R₉+R₁₀) and resistance R₁₁Both sides resistance is equivalent to resistance r₁, resistance R₁₁With resistance R₁Both sides resistance is equivalent to resistance r₁' resistance (R₂+R₃+…+R₉+R₁₀) and resistance R₁Both sides resistance is equivalent to resistance r₁", it is equivalent to resistance r₁、r₁’、r₁" intersection point be Q₁：Then r₁=(R₂+R₃+…+R₉+R₁₀)×R₁₁/(R₁+R₂+…+R₁₀+R₁₁The Ω of the Ω of)=9 × 110 × 110/11 × 110=90

r₁'=R₁×R₁₁/(R₁+R₂+…+R₁₀+R₁₁The Ω of the Ω of)=110 × 110/11 × 110=10

r₁"=(R₂+R₃+…+R₉+R₁₀)×R₁/(R₁+R₂+…+R₁₀+R₁₁The Ω of the Ω of)=9 × 110 × 110/11 × 110=90

Resistance value between node B and node D is equal to (2100 Ω+r₁)×(1900Ω+200Ω+r₁”)/(2×2190)Ω+r₁The Ω of the '=2190 Ω/2+10 Ω=Ω of 1095 Ω+10=1105

When second step disc puts " 2 ", the calculating of the resistance value between node B and node D：If resistance (R₃+R₄+…+R₉+R₁₀) and resistance R₁₁Both sides resistance is equivalent to resistance r₂, resistance R₁₁With resistance (R₁+R₂) both sides resistance is equivalent to resistance r₂' resistance (R₃+R₄+…+R₉+R₁₀) and resistance (R₁+R₂) both sides resistance is equivalent to resistance r₂", it is equivalent to resistance r₂、r₂’、r₂" intersection point be Q₂：

Then r₂=80 Ω r₂The Ω r of '=20₂The Ω of "=160

Resistance value between node B and node D is equal to (2100 Ω+r₂)×(1900Ω+120Ω+r₂”)/(2×2180)Ω+r₂The Ω of the '=2180 Ω/2+20 Ω=Ω of 1090 Ω+20=1110.

Similarly, when the second step disc puts " 3 ", the resistance value between node B and node D is 1115 Ω,

When second step disc puts " 4 ", the resistance value between node B and node D is 1120 Ω,

When second step disc puts " 5 ", the resistance value between node B and node D is 1125 Ω,

……

When step disc puts " 10 ", the resistance value between node B and node D is 1150 Ω.Because Measuring plate II increases by 5 Ω per stepping, therefore bracket panel II ' reduces by 5 Ω per stepping, circuit is always hindered constant；When the first or second step disc reset, the resistance value between node B and node D is 1100 Ω, and bracket panel II ' 10 × 5 Ω resistance fully enter circuit.

When three, the 4th step discs put different indicating values, resistance between node D and node E changes between the Ω of 5002.728 Ω~5002.780, the Ω resistance R of node E connections 147.25₁₆Afterwards, from node A by node D to switch K₁× 10 resistance value between range contact is 6300 Ω, 0.05 Ω change in resistance, the relative change to 6300 Ω is less than ten a ten thousandths, and influence can be ignored.

Electric current when pressure measuring instrument operating current is standardized is 2mA, in × 10 range, 700 Ω range swithching resistance R₁₇And 70 Ω range swithching resistance R₁₈Not to operating current shunt, so 2mA electric currents from node A to node B again to node D.

In × 10 range, Measuring plate II put " n " (n=1,2,3 ... 9) when, the measured disk I of node B are to being equivalent to resistance r_n、r_n’、r_n" intersection point Qn (n=1,2,3 ... 9) with pass through 1900 Ω resistance R₁₂To intersection point Q_nResistance value is equal, when Measuring plate II puts " 10 ", and node B measured disk I to node C resistance value is with passing through 1900 Ω resistance R₁₂Resistance value to node C is equal to 2100 Ω, so flowing through Measuring plate I and 1900 Ω resistance R₁₂Electric current also respectively be 1mA.1mA electric currents flow through the ohmically voltages of 100 Ω for 100mV, and Measuring plate I is 100mV per stepping.

When not considering Measuring plate I, for 11 end to end resistance rings of 110 Ω of the Measuring plate II between 1~10 contact, resistance R during Measuring plate II sets₁It is all 110 Ω resistor coupled in parallel with 10 resistances, flows through resistance R₁₁Electric current be 1/11mA, the voltage U between node C and node D_CD=1/11 × 110mV=10mV；Resistance (R when Measuring plate II puts " 2 "₁+R₂) with 9 resistances be all 110 Ω resistor coupled in parallel, flow through resistance R₁₁Electric current be 2/11mA, the voltage U between node C and node D_CD=2/11 × 110mV=20mV；Similarly, the voltage U of (n=1,2,3 ... 10) between resistance nodes C and node D when Measuring plate II puts " n "_CD=n × 10mV；；As Measuring plate I and Measuring plate II resets, electric current is without resistance R₁₁, U_CD=0mV.

100mV voltage superposition of the Measuring plate I electric current between node C, D is flowed through when Measuring plate I not resets on Measuring plate II, instead of the resistance between the 0 of Measuring plate I, 1 contact.

2mA operating currents are divided into three tunnels after first, second step disc to node D：5293.92 Ω resistance R are passed through in measured disk IV all the way, another road by replacement disk III ', another road₁₃, three tunnel current remittances are together in node E.Resistance is change between node D and node E when three, the 4th step discs put different indicating values, resistance is minimum between node D and node E during the three, the 4th step disc reset indicating values, resistance is maximum between node D and node E when three, the 4th step discs put " 10 " indicating value, median is taken for this, resistance is not having resistance R between node D and node E when the three, the 4th step discs put " 5 " indicating value₁₃It is (10 when in parallel⁶÷ 11+50) Ω, in order that the total current for flowing through the three, the 4th step discs is 0.11mA, with 5293.92 Ω resistance R₁₃Shunt 1.89mA electric current；During the three, the 4th step disc reset indicating values, the total current for flowing through the three, the 4th step discs is 0.11001mA, when the three, the 4th step discs put " 10 " indicating value, and the total current for flowing through the three, the 4th step discs is 0.10999mA, error is a ten thousandth, and influence can be ignored；Flow through resistance R₁₄With resistance R₁₅Electric current than exact value be 10, in the three, the 4th step disc reset indicating values, flow through resistance R₁₄With resistance R₁₅Current ratio be 9.995, when the three, the 4th step discs put " 10 " indicating value, flow through resistance R₁₄With resistance R₁₅Current ratio be 10.005, error is 5/10000ths, and due to being last two disk, influence can also be ignored；The 3rd step disc gets 0.1mA electric currents on Measuring plate III resistance, and the resistance that the 4th step disc gets on 0.01mA electric currents, Measuring plate III is 10 Ω, and the 3rd step disc is 1mV per stepping, and the 4th step disc is 0.1mV per stepping.

When × 10 range operating currents are standardized, the first step disc puts n₁, the second step disc put n₂, the 3rd step disc put n₃, the 4th step disc put n₄, at this moment " U_x" voltage is between two measurement terminals：

U_x=100n₁+10n₂+1n₃+0.1n₄ (mV)

During × 1 range, node A passes through node D to range selector K₁Middle K_1-2× the 1 6300 Ω resistance and 700 Ω resistance R between range contact₁₇Parallel connection, 6300 Ω are 9 times of 700 Ω, therefore, and 1/10 operating current is that 0.2mA electric currents flow through node B by node D to range selector K₁Middle K_1-2× 1 range contact, it is in parallel after the resistance value that reduces by connecting into 5670 Ω auxiliary resistances R₂₁Carry out holding circuit and always hinder constant；At this moment the first step disc puts n₁, the second step disc put n₂, the 3rd step disc put n₃, the 4th step disc put n₄, " U_x" voltage is between two measurement terminals：

U_x=10n₁+1n₂+0.1n₃+0.01n₄ (mV)

During × 0.1 range, node A passes through node D to range selector K₁Middle K_1-2× 0.1 630 Ω resistance R that have been 6300 Ω resistant series between range contact₁₉Sum is equal to 6930 Ω, resistance R connected in parallel₁₈It is 70 Ω, 6930 Ω are 99 times of 70 Ω, therefore, 1/100 operating current is that 0.02mA electric currents flow through node B by node D to resistance R₁₉, the resistance value reduced after parallel connection is by connecting into 560.7 Ω auxiliary resistances R₂₂With 5670 Ω auxiliary resistances R₂₁Carry out holding circuit and always hinder constant；At this moment the first step disc puts n₁, the second step disc put n₂, the 3rd step disc put n₃, the 4th step disc put n₄, " U_x" voltage is between two measurement terminals：

U_x=n₁+0.1n₂+0.01n₃+0.001n₄ (mV)

During × 0.01 range, node A passes through node D to range selector K₁Middle K_1-2× 0.01 630 Ω resistance R that have been 6300 Ω resistant series between range contact₁₉And 63000 Ω resistance R₂₀Sum is equal to 69930 Ω, resistance R connected in parallel₁₈It is 70 Ω, 69930

Ω is 999 times of 70 Ω, therefore, and 1/1000 operating current is that 0.002mA electric currents flow through node B by node D to range selector K₁Middle K_1-2× 0.01 range contact, it is in parallel after the resistance value that reduces by connecting into 560.07 Ω auxiliary resistances R₂₃With 5670 Ω auxiliary resistances R₂₁Carry out holding circuit and always hinder constant；At this moment the first step disc puts n₁, the second step disc put n₂, the 3rd step disc put n₃, the 4th step disc put n₄, " U_x" voltage is between two measurement terminals：

U_x=0.1n₁+0.01n₂+0.001n₃+0.0001n₄ (mV)

Electromotive force per series-produced normal cell is discrete, between 1.0188V~1.0196V, and the operating current of standardization is 2mA, therefore sets up resistance R_NTake 509 Ω, the additional lockable adjustable resistance R of 0~1 Ω_P3, can be with the excursion of coverage criteria cell emf.

Node A to setting resistance R_NHot end between the resistances of four ranges be all 6300 Ω, 509 Ω setting resistance R_NWith 0~1 Ω adjustable resistances R_P3Be 510 Ω, 6810 Ω, undertakes about 13.62V voltages altogether；Pressure measuring instrument external power supply using dry cell power supply it is necessary to ten groups of dry cells as connected, in order that in the case of new, old the operating current of pressure measuring instrument can be adjusted to standardization, therefore, taking adjustable resistance R dry cell_P1For 20 × 70 Ω, adjustable resistance R _p20~75 Ω, dry cell voltage is using scope between 13.62V~16.57V, and this pressure measuring instrument external power supply is proposed with Shanghai Xin Xin electronics factory production YJ49b type voltage-stabilized power supplies, and it has multi gear high stability voltage output.

The normalized current of pressure measuring instrument is obtained by：2V standard signals voltage by polarity and pressure measuring instrument " U_x" two measurement terminal connections, the total indicating value of each step disc of pressure measuring instrument is identical with standard signal magnitude of voltage, double-point double-throw switch K₂Throw to the left side, regulation adjustable resistance R_P1And adjustable resistance R_P2, make galvanometer G nullings；Again by double-point double-throw switch K₂Throw to the right, regulation adjustable resistance R_P3, make galvanometer G nullings, after repeating once, adjustable resistance R_P3Locking, at this moment the operating current of pressure measuring instrument is just standardized.

Claims

1. a kind of novel pressure measuring instrument, the resistance measurement network that is made up of four step discs, range swithching resistance and range selector is passed through from the positive pole of external 15V working powers to 509 Ω setting resistance R_NAnd 0~1 lockable adjustable resistance R of Ω_P3Pass through 0~75 Ω adjustable resistances R again_P2And 20 × 70 Ω adjustable resistance R_P1The negative pole for returning to external 15V working powers constitutes the performance loop of pressure measuring instrument；Normal cell E_NPositive pole is by being connected to galvanometer G double-point double-throw switch K between two normally-closed contacts₂To setting resistance R_NAnd lockable adjustable resistance R_P3Sliding contact, then pass through 75K Ω current-limiting resistances R to normal cell E_NNegative pole constitutes the standard loop of pressure measuring instrument；For connecting measured " U_X" two terminals, positive pole terminal is after four measurement disks, then by being connected to galvanometer G double-point double-throw switch K between two normally-closed contacts₂The compensation loop of pressure measuring instrument is constituted to negative pole terminal；It is characterized in that the first step disc has Measuring plate I, it has 0~22 totally 23 gears, in addition to being directly connected between 0,1 contact, 100 Ω resistance one is connected between remaining each shelves contact, separately there is bracket panel I ' and bracket panel I "; bracket panel I ' brush is circuit node B with the tie point that bracket panel I " brush is connected with wire, bracket panel I ' 0 contact and bracket panel I " 0 contact are isolated, and remaining all contact is connected with wire；Second step disc is made up of Measuring plate II with bracket panel II ', and Measuring plate II has 0~10 totally 11 gears, and the resistance for having 11 110 Ω above is circlewise connected：1st resistance R₁Weld the 2nd resistance R in one end₂One end, resistance R₂The other end welds the 3rd resistance R₃One end, resistance R₃The other end welds the 4th resistance R₄One end, resistance R₄The other end welds the 5th resistance R₅One end, resistance R₅The other end welds the 6th resistance R₆One end, resistance R₆The other end welds the 7th resistance R₇One end, resistance R₇The other end welds the 8th resistance R₈One end, resistance R₈The other end welds the 9th resistance R₉One end, resistance R₉The other end welds the 10th resistance R₁₀One end, the 10th resistance R₁₀The other end and the 11st resistance R₁₁One end tie point be circuit node C, the 11st resistance R₁₁The other end and the 1st resistance R₁The other end to be connected to 0 contact of Measuring plate in 0 contact of Measuring plate in the 3rd step disc, the 3rd step disc be circuit node D, resistance R₁With resistance R₂Tie point pass through 200 Ω resistance and the 1st contact portion, resistance R₂With resistance R₃Tie point pass through 120 Ω resistance and the 2nd contact portion, resistance R₃With resistance R₄Tie point pass through 60 Ω resistance and the 3rd contact portion, resistance R₄With resistance R₅Tie point pass through 20 Ω resistance and the 4th contact portion, resistance R₅With resistance R₆Tie point and the 5th contact portion, resistance R₆With resistance R₇Tie point and the 6th contact portion, resistance R₇With resistance R₈Tie point pass through 20 Ω resistance and the 7th contact portion, resistance R₈With resistance R₉Tie point pass through 60 Ω resistance and the 8th contact portion, resistance R₉With resistance R₁₀Tie point pass through 120 Ω resistance and the 9th contact portion, resistance R₁₀With resistance R₁₁Tie point pass through 200 Ω resistance and the 10th contact portion, resistance R₁With resistance R₁₁The node D of connection passes through 300 Ω resistance and 0 contact portion, and the bracket panel II ' of the second step disc is above 10 5 Ω resistance；3rd step disc is made up of Measuring plate III with replacement disk III ', is 10 10 Ω resistance on Measuring plate III, is 10 10 Ω resistance on replacement disk III ', the brush of Measuring plate III brush and replacement disk III ' is with a piece of metallic brush piece；4th step disc only has Measuring plate IV, its each contact and the corresponding contact portion on Measuring plate III；The contacts of bracket panel II ' the 10th and 700 Ω range swithching resistance R₁₇One end and 70 Ω range swithching resistance R₁₈One end be parallel to node A, the positive pole of the external working power of node A connection pressure measuring instruments, 700 Ω range swithching resistance R₁₇Other end connection range selector K₁Middle K_1-1Layer × 1 range contact, 70 Ω range swithching resistance R₁₈Other end connection range selector K₁Middle K_1-1Layer × 0.1 and × 0.01 range contact, bracket panel II ' 0 contact portion bracket panel I " 0 contact, the other contacts of bracket panel II ' brush connection bracket panel I " in addition to 0 contact, Measuring plate II brush passes through 1900 Ω resistance R₁₂Connecting node B afterwards, other contact portion Measuring plate I 22nd contacts of the bracket panel I ' in addition to 0 contact, Measuring plate I the 0th, 1 contact are connected with node C, and bracket panel I ' 0 contact is connected after 2200 Ω resistance with node D, Measuring plate IV brush series connection 1000k Ω resistance R₁₅Afterwards with 147.25 Ω resistance R₁₆One end tie point be circuit node E, replacement disk III ' the Ω resistance R of the 10th contact series 99950₁₄Connecting node E, 5293.92 Ω resistance R afterwards₁₃One end connecting node D, the other end connecting node E, 147.25 Ω resistance R₁₆The other end be connected to range selector K₁Middle K_1-1Layer × 10 range contacts, range selector K₁Middle K_1-1Layer × 10 range contact and range selector K₁Middle K_1-2Layer × 1 range contact connected with wire, K_1-2Layer × 1 range contact and × 0.1 pass through 630 Ω resistance R between range contact₁₉Connection, K_1-2Layer × 0.1 range contact and × 0.01 pass through 63000 Ω resistance R between range contact₂₀Connection, 5670 Ω resistance R₂₁One end pass through 560.07 Ω resistance R₂₃Connect range selector K₁Middle K_1-3Layer × 0.01 range contact, pass through 560.7 Ω resistance R₂₂Connect range selector K₁Middle K_1-3Layer × 0.1 range contact and with range selector K₁Middle K_1-3Layer × 1 range contact connected with wire, 5670 Ω resistance R₂₁The other end and range selector K₁Middle K_1-3Layer × 10 range contact all with set up resistance R_NHot end connection, range selector K₁In three layers of K_1-1Layer, K_1-2Layer, K_1-3Three normally-closed contacts of layer are connected with wire；For connecting measured " U_X" two measurement terminals, positive pole is connected with Measuring plate I brushes, and negative pole is by double-point double-throw switch K₂Afterwards with Measuring plate III the 10th contact portion.