CN106093514A - A kind of electric bridge measuring wide range - Google Patents

Abstract

A kind of for direct current resistance m easurem ent, the electric bridge that is made up of six brachium pontis, its comparison arm is made up of four step discs, can measure the broad range from general resistance to high resistant.

Description

A kind of electric bridge measuring wide range

Technical field

The present invention relates to the instrument that D.C. resistance is measured.

Background technology

Currently for measuring 10⁶More than Ω resistance is it is necessary to use megohm bridge, and megohm bridge typically contains megohm box, high The measuring resistance of resistance, big due to resistance during measurement, the supply voltage used is the highest, sometimes more than 1000V, and megohm bridge insulate Require height, in addition it is also necessary to complicated shielding harness.

Summary of the invention

It is an object of the invention to design a kind of electric bridge measuring wide range, it need not megohm box and high value standard electricity Resistance, only with resistance 10⁴The general resistance of below Ω, measures the upper limit up to 10¹²The resistance of Ω resistance.

The first technical scheme of the present invention is so taked: it has for connecting measured " R_X" one by test arm, have four The comparison arm R of step disc composition₂, compare arm R₂The first step disc be have 0,1, the measurement dish of 2 ... 10 totally 11 gears I, measurement dish I welds between each two adjacent contacts 10000 Ω resistance one, the second step disc be have 0,1,2 ... 10 totally 11 The measurement dish II of individual gear, measurement dish II welds between each two adjacent contacts 1000 Ω resistance one, and the 3rd step disc is to have 0,1, the measurement dish III of 2 ... 10 totally 11 gears, measurement dish III welds between each two adjacent contacts 100 Ω resistance one Only, the 4th step disc be have 0,1, the measurement dish IV of 2 ... 10 totally 11 gears, on measurement dish IV between each two adjacent contacts Weld 10 Ω resistance one；It separately has four brachium pontis, and the galvanometer G top b being connected with by test arm is through brachium pontis R₃Upper 100 Ω electricity Resistance r₁Connect 900 Ω resistance r₂With brachium pontis R behind one end₃× 1 amount limit contact connects, resistance r₂The other end connects 9000 Ω resistance r₃One With brachium pontis R after end₃× 10 amount limit contacts connect, 9000 Ω resistance r₃The other end and brachium pontis R₃×10²、×10³、×10⁴、×10⁵、 ×10⁶、×10⁷、×10⁸Amount limit contact connects, brachium pontis R₃Metal contact ring is connected with electric bridge node c, another end segment of galvanometer G Point e is through brachium pontis R₄Upper 1 Ω resistance r₄Afterwards with brachium pontis R₄×10⁵、×10⁶、×10⁷、×10⁸Amount limit contact connects, brachium pontis R₄Go up it Surplus limit contact disconnects with circuit, brachium pontis R₄Metal contact ring is connected with electric bridge node c, brachium pontis R₅×1、×10、×10²Amount limit Contact is through 99 Ω resistance r₅With × 10⁴Amount limit contact connects, brachium pontis R₅×10³Amount limit contact is through 9 Ω resistance r₆With × 10⁴、 ×10⁵、×10⁶、×10⁷、×10⁸Amount limit contact connects, brachium pontis R₅×10⁸Amount limit contact is through 1 Ω resistance r₇With electric bridge node c Connect, brachium pontis R₅Metal contact ring is connected with electric bridge node d, brachium pontis R₆×1、×10、×10²、×10³、×10⁴Amount limit contact is all Directly it is connected with node e, brachium pontis R₆×10⁵Amount limit contact is through 10 Ω resistance r₈It is connected with node e, brachium pontis R₆×10⁶Amount limit is touched O'clock through 100 Ω resistance r₉It is connected with node e, brachium pontis R₆×10⁷Amount limit contact is through 1000 Ω resistance r₁₀It is connected with node e, bridge Arm R₆×10⁸Amount limit contact is through 10000 Ω resistance r₁₁It is connected with node e, brachium pontis R₆Metal contact ring is connected with electric bridge node d, Relatively arm R₂One end connects node d, and the other end connects node a, is connected with node a and also has by test arm one end and power supply E one end, quilt The test arm other end connects node b, and the power supply E other end connects node c.

The second technical scheme of the present invention is so taked: it has for connecting measured " R_X" one by test arm, have four The comparison arm R of step disc composition₂, compare arm R₂The first step disc be have 0,1, the measurement dish of 2 ... 10 totally 11 gears I, measurement dish I welds between each two adjacent contacts 10000 Ω resistance one, the second step disc be have 0,1,2 ... 10 totally 11 The measurement dish II of individual gear, measurement dish II welds between each two adjacent contacts 1000 Ω resistance one, and the 3rd step disc is to have 0,1, the measurement dish III of 2 ... 10 totally 11 gears, measurement dish III welds between each two adjacent contacts 100 Ω resistance one Only, the 4th step disc be have 0,1, the measurement dish IV of 2 ... 10 totally 11 gears, on measurement dish IV between each two adjacent contacts Weld 10 Ω resistance one；It is characterized in that it separately has four brachium pontis, the galvanometer G top b being connected with by test arm is through brachium pontis R₃Upper 100 Ω resistance r₁Connect 900 Ω resistance r₂With brachium pontis R behind one end₃× 1 amount limit contact connects, resistance r₂The other end connects 9000 Ω resistance r₃With brachium pontis R behind one end₃× 10 amount limit contacts connect, 9000 Ω resistance r₃The other end and brachium pontis R₃×10²、× 10³、×10⁴、×10⁵、×10⁶、×10⁷、×10⁸Amount limit contact connects, brachium pontis R₃Metal contact ring is connected with electric bridge node c, Galvanometer G other end node e is through brachium pontis R₄Upper 1 Ω resistance r₄Afterwards with brachium pontis R₄×10⁵、×10⁶、×10⁷、×10⁸Amount limit is touched Point connects, brachium pontis R₄Upper its surplus limit contact disconnects with circuit, brachium pontis R₄Metal contact ring is connected with electric bridge node c, brachium pontis R₅× 1、×10、×10²Amount limit contact is through 99 Ω resistance r₅With × 10⁴Amount limit contact connects, brachium pontis R₅×10³Amount limit contact is through 9 Ω resistance r₆With × 10⁴、×10⁵、×10⁶、×10⁷、×10⁸Amount limit contact connects, brachium pontis R₅×10⁸Amount limit contact is through I Ω electricity Resistance r₇It is connected with electric bridge node c, brachium pontis R₅Metal contact ring is connected with electric bridge node d, brachium pontis R₆×1、×10、×10²、×10³、 ×10⁴Amount limit contact is all directly connected with node e, brachium pontis R₆×10⁵×10⁶、×10⁷、×10⁸Amount limit contact is through 1M Ω resistance r₁₂It is connected with node e, brachium pontis R₆Metal contact ring is connected with electric bridge node d, brachium pontis R₃, brachium pontis R₄, brachium pontis R₅, brachium pontis R₆On Brush is all put and is limited gear in same amount, and during rotation, four brushes synchronize；Relatively arm R₂One end connects node d, and the other end connects Node a, is connected with node a and also has by test arm one end and power supply E one end, connected node b, the power supply E other end by the test arm other end Connect node c.

By above technical scheme, except connecting measured " R_x" by test arm outside, remaining brachium pontis is all general resistance Resistance is the lowest to the insulating requirements of material, it is also possible to reducing shielding measure, owing to resistance is low, power supply avoids the need for height Pressure, as long as employing 30～60V is the most permissible.

Accompanying drawing explanation

Fig. 1 is principle of the invention circuit.Dotted portion is for carrying out triangle star-like conversion offer reference.

Fig. 2 is that Fig. 1 carries out equivalent circuit after the star-like conversion of triangle.

Fig. 3 is the first circuit diagram of the present invention.

Fig. 4 is another kind circuit diagram of the present invention.

Detailed description of the invention

In figure 3, arm R is compared₂The resistance of upper 10 × 10000 Ω of measurement dish I, represents that measurement dish I is by 10 10000 Ω electricity Resistance composition, remaining measurement dish in like manner, the most too.

In Fig. 3, Fig. 4, all brachium pontis, compare heavy black bar on arm represent metal contact ring, hollow small circle represent gold Belonging to contact, four-headed arrow represents metallic brush.

Fig. 1 is principle of the invention circuit, to Fig. 1 bridge arm R₄, brachium pontis R₅, brachium pontis R₆Carry out the star-like conversion of triangle:

$R_C=\frac{R_4\×R_5}{R_4+R_5+R_6}...\left(1\right)$

$R_E=\frac{R_4\×R_6}{R_4+R_5+R_6}...\left(2\right)$

$R_D=\frac{R_5\×R_6}{R_4+R_5+R_6}...\left(3\right)$

Can have according to Fig. 2:

$\begin{array}{c}{R}_X=\frac{R_3\×(R_2+R_D)}{R_C}=\frac{R_4+R_5+R_6}{R_4{R}_5}\×\frac{R_2{R}_3(R_4+R_5+R_6)+R_3(R_5\×R_6)}{R_4+R_5+R_6}\\ =\frac{R_2{R}_3{R}_4+R_2{R}_3{R}_5+R_2{R}_3{R}_6+R_3{R}_5{R}_6}{R_4{R}_5}=\frac{R_2{R}_3{R}_6}{R_4{R}_5}+\frac{R_2{R}_3}{R_5}+\frac{R_2{R}_3}{R_4}+\frac{R_3{R}_6}{R_4}\end{array}...\left(4\right)$

Understand from (4) formula and increase brachium pontis R₂, brachium pontis R₃, brachium pontis R₆Resistance value, reduces brachium pontis R₄, brachium pontis R₅Resistance value, just The resistance that resistance is the biggest can be measured, when electric bridge precision is the highest, can ignore for latter three:

$R_X\≈\frac{R_2{R}_3{R}_6}{R_4{R}_5}...\left(5\right)$

In figure 3, the first circuit uses 10000 Ω brachium pontis R₃, 10000 Ω brachium pontis R₆, compare arm R₂Also up to 10000 Ω, brachium pontis R₄, brachium pontis R₅Resistance value is 1 Ω, at this moment

$R_X=\frac{{10}^4\×{10}^4\×{10}^4}{1\×1}+{\frac{{10}^4\×10}{1}}^4+\frac{{10}^4\×{10}^4}{1}+\frac{{10}^4\×{10}^4}{1}$

R_X=10¹²+3×10⁸Ω

Ignore rear three errors caused:

$\mathrm{\δ}=\frac{3\×{10}^8}{{10}^{12}+3\×{10}^8\mathrm{\Ω}}\≈0.03\%$

When electric bridge precision is 0.5 grade, this error can be disregarded.

Brachium pontis R₃The resistance prescribed a time limit in electric bridge in × 1 amount is 100 Ω, and × 10 amounts are 100 Ω resistance r in limited time₁Series connection 900 Ω resistance r₂, the resistance in electric bridge is 1000 Ω, × 10²Amount is 1000 Ω resistant series 9000 Ω resistance r in limited time₃, in electric bridge Resistance is 10000 Ω, and the most each amount limit is all 10000 Ω in electric bridge.

Brachium pontis R₄× 1 amount limit, × 10 amounts limit, × 10²Amount limit, × 10³Amount limit, × 10⁴Amount limit all departs from bridge circuit, × 10⁵Amount limit, × 10⁶Amount limit, × 10⁷Amount limit, × 10⁸Amount limit has 1 Ω resistance r₄Enter circuit.

Brachium pontis R₅× 1 amount limit, × 10 amounts limit, × 10²Amount is 1 Ω resistance r in limited time₇Connect 99 Ω resistance r₅At electric bridge electricity Road bridge arm R₅Indicating value be 100 Ω resistance, brachium pontis R₅× 10³Amount is 1 Ω resistance r in limited time₇Connect 9 Ω resistance r₆, at electric bridge Circuit bridge arm R₅Indicating value be 10 Ω resistance, brachium pontis R₅Other amounts limit resistance value in bridge be 1 Ω.

It is brachium pontis R between electric bridge node e and node d₆, × 1 amount limit, × 10 amounts limit, × 10²Amount limit, × 10³Amount limit, × 10⁴Amount in limited time, is directly to turn between node e and node d, brachium pontis R₅× 10⁵Amount is 10 Ω between node e and node d in limited time Resistance r₈, × 10⁶Amount is 100 Ω resistance r between node e and node d in limited time₉, × 10⁷Amount node e in limited time and node d it Between be 1000 Ω resistance r₁₀, × 10⁸Amount is 10000 Ω resistance r between node e and node d in limited time₁₁。

× 1 amount limit, × 10 amounts limit, × 10²Amount limit, × 10³Amount limit, × 10⁴Amount is prescribed a time limit, brachium pontis R₄Depart from bridge circuit, At this moment it is a single bridges, so

R_X=(R₃/R₅)×R₂Brachium pontis R is limited in × 1 amount₃=brachium pontis R₅=100 Ω, so ratio is 1；Bridge is limited in × 10 amounts Arm R₃=1000 Ω, brachium pontis R₅=100 Ω, so ratio is 10；× 10²Amount limit brachium pontis R₃=10000 Ω, brachium pontis R₅=100 Ω, so ratio is 100；× 10³Amount limit brachium pontis R₃=10000 Ω, brachium pontis R₅=10 Ω, so ratio is 1000；× 10⁴Amount limit brachium pontis R₃=10000 Ω, brachium pontis R₅=1 Ω, so ratio is 10000.Other amounts limit brachium pontis R₄Access bridge circuit, At this moment

R_X=(R₃R₆/R₄R₅)×R₂, × 10⁵Amount limit brachium pontis R₃=10000 Ω, brachium pontis R₆=10 Ω, brachium pontis R₄=brachium pontis R₅=1 Ω, at this moment by test arm R_XIt is to compare arm R₂100,000 times；× 10⁶Amount limit brachium pontis R₃=10000 Ω, brachium pontis R₆=100 Ω, brachium pontis R₄=brachium pontis R₅=1 Ω, at this moment by test arm R_XIt is to compare arm R₂1,000,000 times；× 10⁷Amount limit brachium pontis R₃= 10000 Ω, brachium pontis R₆=1000 Ω, brachium pontis R₄=brachium pontis R₅=1 Ω, at this moment by test arm R_XIt is to compare arm R₂10,000,000 times；? ×10⁸Amount limit brachium pontis R₃=10000 Ω, brachium pontis R₆=10000 Ω, brachium pontis R₄=brachium pontis R₅=1 Ω, at this moment by test arm R_XIt is to compare Arm R₂100,000,000 times.

In the diagram, another kind of circuit uses 10000 Ω brachium pontis R₃, 1M Ω brachium pontis R₆, compare arm R₂Also up to 10000 Ω, Brachium pontis R₄, brachium pontis R₅Resistance value is 1 Ω, × 10⁵、×10⁶、×10⁷、×10⁸, amount in limited time

$R_X=\frac{{10}^4\×{10}^4\×{10}^6}{1\×1}+{\frac{{10}^4\×10}{1}}^4+\frac{{10}^4\×{10}^4}{1}+\frac{{10}^4\×{10}^6}{1}$

R_X=10¹⁴+1.02×10¹⁰Ω

Ignore rear three errors caused:

$\mathrm{\δ}=\frac{1.02\×{10}^{10}}{{10}^{14}+1.02\×{10}^{10}\mathrm{\Ω}}\≈0.01\%$

When electric bridge precision is 0.1 grade, this error can be disregarded.Other amounts limit is same with Fig. 3.

Claims (2)

1. measuring an electric bridge for wide range, it has for connecting measured " R_X" one by test arm, be made up of four step discs Comparison arm R₂, compare arm R₂The first step disc be have 0,1, the measurement dish I of 2 ... 10 totally 11 gears, every on measurement dish I Weld 10000 Ω resistance one between two adjacent contacts, the second step disc be have 0,1, the measurement of 2 ... 10 totally 11 gears Dish II, measurement dish II welds between each two adjacent contacts 1000 Ω resistance one, the 3rd step disc be have 0,1,2 ... 10 The measurement dish III of totally 11 gears, measurement dish III welds between each two adjacent contacts 100 Ω resistance one, the 4th step disc Be have 0,1, the measurement dish IV of 2 ... 10 totally 11 gears, measurement dish IV welds between each two adjacent contacts 10 Ω resistance one Only；It is characterized in that it separately has four brachium pontis, the galvanometer G top b being connected with by test arm is through brachium pontis R₃Upper 100 Ω resistance r₁ Connect 900 Ω resistance r₂With brachium pontis R behind one end₃× 1 amount limit contact connects, resistance r₂The other end connects 9000 Ω resistance r₃One end Afterwards with brachium pontis R₃× 10 amount limit contacts connect, 9000 Ω resistance r₃The other end and brachium pontis R₃×10²、×10³、×10⁴、×10⁵、× 10⁶、×10⁷、×10⁸Amount limit contact connects, brachium pontis R₃Metal contact ring is connected with electric bridge node c, galvanometer G other end node e Through brachium pontis R₄Upper 1 Ω resistance r₄Afterwards with brachium pontis R₄×10⁵、×10⁶、×10⁷、×10⁸Amount limit contact connects, brachium pontis R₄Go up remaining Amount limit contact disconnects with circuit, brachium pontis R₄Metal contact ring is connected with electric bridge node c, brachium pontis R₅×1、×10、×10²Amount limit is touched O'clock through 99 Ω resistance r₅With × 10⁴Amount limit contact connects, brachium pontis R₅×10³Amount limit contact is through 9 Ω resistance r₆With × 10⁴、× 10⁵、×10⁶、×10⁷、×10⁸Amount limit contact connects, brachium pontis R₅×10⁸Amount limit contact is through 1 Ω resistance r₇With electric bridge node c even Connect, brachium pontis R₅Metal contact ring is connected with electric bridge node d, brachium pontis R₆×1、×10、×10²、×10³、×10⁴Amount limit contact is the most straight Connect and be connected with node e, brachium pontis R₆×10⁵Amount limit contact is through 10 Ω resistance r₈It is connected with node e, brachium pontis R₆×10⁶Amount limit contact Through 100 Ω resistance r₉It is connected with node e, brachium pontis R₆×10⁷Amount limit contact is through 1000 Ω resistance r₁₀It is connected with node e, brachium pontis R₆×10⁸Amount limit contact is through 10000 Ω resistance r₁₁It is connected with node e, brachium pontis R₆Metal contact ring is connected with electric bridge node d, bridge Arm R₃, brachium pontis R₄, brachium pontis R₅, brachium pontis R₆On brush all put same amount limit gear, during rotation, four brushes synchronize；Relatively Arm R₂One end connects node d, and the other end connects node a, is connected with node a and also has by test arm one end and power supply E one end, by test arm The other end connects node b, and the power supply E other end connects node c.

2. measuring an electric bridge for wide range, it has for connecting measured " R_X" one by test arm, be made up of four step discs Comparison arm R₂, compare arm R₂The first step disc be have 0,1, the measurement dish I of 2 ... 10 totally 11 gears, every on measurement dish I Weld 10000 Ω resistance one between two adjacent contacts, the second step disc be have 0,1, the measurement of 2 ... 10 totally 11 gears Dish II, measurement dish II welds between each two adjacent contacts 1000 Ω resistance one, the 3rd step disc be have 0,1,2 ... 10 The measurement dish III of totally 11 gears, measurement dish III welds between each two adjacent contacts 100 Ω resistance one, the 4th step disc Be have 0,1, the measurement dish IV of 2 ... 10 totally 11 gears, measurement dish IV welds between each two adjacent contacts 10 Ω resistance one Only；It is characterized in that it separately has four brachium pontis, the galvanometer G top b being connected with by test arm is through brachium pontis R₃Upper 100 Ω resistance r₁ Connect 900 Ω resistance r₂With brachium pontis R behind one end₃× 1 amount limit contact connects, resistance r₂The other end connects 9000 Ω resistance r₃One end Afterwards with brachium pontis R₃× 10 amount limit contacts connect, 9000 Ω resistance r₃The other end and brachium pontis R₃×10²、×10³、×10⁴、×10⁵、× 10⁶、×10⁷、×10⁸Amount limit contact connects, brachium pontis R₃Metal contact ring is connected with electric bridge node c, galvanometer G other end node e Through brachium pontis R₄Upper 1 Ω resistance r₄Afterwards with brachium pontis R₄×10⁵、×10⁶、×10⁷、×10⁸Amount limit contact connects, brachium pontis R₄Go up remaining Amount limit contact disconnects with circuit, brachium pontis R₄Metal contact ring is connected with electric bridge node c, brachium pontis R₅×1、×10、×10²Amount limit is touched O'clock through 99 Ω resistance r₅With × 10⁴Amount limit contact connects, brachium pontis R₅×10³Amount limit contact is through 9 Ω resistance r₆With × 10⁴、× 10⁵、×10⁶、×10⁷、×10⁸Amount limit contact connects, brachium pontis R₅×10⁸Amount limit contact is through 1 Ω resistance r₇With electric bridge node c even Connect, brachium pontis R₅Metal contact ring is connected with electric bridge node d, brachium pontis R₆×1、×10、×10²、×10³、×10⁴Amount limit contact is the most straight Connect and be connected with node e, brachium pontis R₆×10⁵×10⁶、×10⁷、×10⁸Amount limit contact is through 1M Ω resistance r₁₂It is connected with node e, bridge Arm R₆Metal contact ring is connected with electric bridge node d, brachium pontis R₃, brachium pontis R₄, brachium pontis R₅, brachium pontis R₆On brush all put in same amount Limit gear, during rotation, four brushes synchronize；Relatively arm R₂One end connects node d, and the other end connects node a, is connected with node a also Having by test arm one end and power supply E one end, connected node b by the test arm other end, the power supply E other end connects node c.