CN201569694U - Voltage measurement device - Google Patents

Abstract

A voltage measurement device used for measuring DC voltages is composed of four step disks, each of which is composed of a measuring disk and a replacing disk, the electric resistance values of the measuring disk and the replacing disk are all integer-time mathematical power of ten, the electric resistances may be compared with a standard resistance on an electric bridge to improve manufacturing precision of the electric resistances so as to improve measuring accuracy of the whole voltage measurement device; the measuring disks are connected directly without conductors and switches, such that there is no effect to measure the electric resistance due to contacting the switches when the device is used to measure.

Description

Voltage measuring apparatus

Technical field

The utility model relates to the instrument of measuring DC voltage.

Background technology

Announced the ZL200510062375.1 patent of invention on May 7th, 2008, it is a kind of voltage measuring apparatus that four step discs are arranged, its the 3rd, the 4th step disc respectively has measuring disk, replacement dish and bracket panel are formed, measuring disk is identical with resistance on the replacement dish, resistance of the every increase of measuring disk, the replacement dish just reduces same resistance, because the 3rd step disc is declined in the time of the 10th, the total resistance of circuit changed when the 4th step disc was put different indicating value, the 3rd step disc is put in the time of the 10th, the total resistance of circuit was constant when the 4th step disc was put different indicating value, the 3rd step disc removes for this reason measuring disk, outside the replacement dish, having increased bracket panel distinguishes step disc and puts the 10th and the circuit of declining the 0 10th. two kind of situation and connect, the 4th step disc has also increased bracket panel, has 10 resistance to insert or cut out several resistance respectively above and makes the total resistance of circuit constant.Four measurement disks is connected two and measures between terminal, and the switch contact resistance variation influence on the step disc is got rid of outside the measurement loop.

Because the 3rd, the 4th step disc all has bracket panel, increased the number of plies of the 3rd, the 4th step disc switch, thereby increased the volume of instrument, also make switch and apparatus structure become complicated, if find in the instrument verification process that particularly the 3rd, the 4th step disc measurement data is overproof, the internal layer resistance that revise the 3rd, the 4th step disc switch bothers very much.Application number 200820120442.4 makes progress than ZL200510062375.1, behind the replacement dish brush of first step disc, is divided into two-way but the electric current of these two kinds of voltage measuring apparatus is flowed through, and through each step disc, merges in the measuring disk brush of first step disc; The problem that it brings is that second and third, four resistances of coiling last resistance all are that two same numbers are formed, and resistance is again little, does not have measuring resistance to compare; As use interim standard resistance, the lead-in wire error between two interim standard resistance is just difficult so; Therefore this voltage measuring apparatus second and third, the resistances of four dishes are difficult to do accurately.

The utility model content

The purpose of this utility model is, when voltage measuring apparatus has four step discs, and contact resistance and variation that the measuring switch stepping is switched, the switch thermoelectrical potential does not influence measurement result; And three, the 4th step disc is all without bracket panel.Making four resistance on the step disc all be designed to resistance is 10 integral number power, and available standards resistance compares at electric bridge, and manufacturing brings convenience to instrument for this.Simultaneously, it also has two ranges.

The technical solution of the utility model is:

Electric current from voltage measuring apparatus 4.5V working power anodal through the resistor network on four step discs between node A, the B and range transfer resistance to single-pole double-throw (SPDT) range selector K ₁Reach 421 Ω setting resistance R N and range of adjustment at the lockable adjustable resistance R of 0～0.5 Ω _P3, again to the resistance R of 405 Ω ₀, the adjustable resistance R of 0～18 Ω _P2Adjustable resistance R through 20 15 Ω resistance compositions _P1Get back to the working power negative pole and form the work loop of voltage measuring apparatus; From standard cell EN positive pole through being connected to galvanometer G double-point double-throw switch K between two normally closed contacts ₂, to setting up resistance R N and lockable adjustable resistance R _P3, arrive the standard cell negative pole again and form the voltage measuring apparatus standard loop; It is characterized in that first step disc between node A, the B is by each I measuring disk and the I ' replacement dish of being made up of 19 100 Ω resistance, the brush of I measuring disk is communicated with the brush of the I ' replacement dish, second step disc passes through 2000 Ω resistance R by each II measuring disk and the II ' replacement dish of being made up of 10 10 Ω resistance between the brush of the brush of II measuring disk and the II ' replacement dish ₁Connect, the 3rd step disc passes through 110 Ω resistance R by each III measuring disk and the III ' replacement dish of being made up of 10 10 Ω resistance between the brush of the brush of III measuring disk and the III ' replacement dish ₃Connect, by IV measuring disk and the IV ' replacement dish that 10 1 Ω resistance are formed, the brush of IV measuring disk is communicated with the brush of the IV ' replacement dish the 4th step disc by each; Be divided into two branch roads behind the anodal connected node A of voltage measuring apparatus working power: left side branch node A connects the II ' replacement and coils the 10th contact, the II ' replacement is coiled the 0th contact and is connected the I ' replacement and coil the 19th contact, I measuring disk the 0th contact connects II measuring disk the 10th contact, II measuring disk the 0th contact connected node B; The right branch node A is by 10450 Ω resistance R ₂The back connects the III ' replacement and coils the 0th contact, and the III ' replacement is coiled the 10th contact and connected the IV ' replacement and coil the 0th contact, and IV measuring disk the 10th contact connects III measuring disk the 0th contact, and III measuring disk the 10th contact is by 395 Ω resistance R ₄Back connected node B; 1000 Ω resistance r ₁An end and voltage measuring apparatus working power anodally be connected Node B and 9000 Ω resistance r ₂An end be connected in parallel on single-pole double-throw (SPDT) range selector K ₁* 1 range contact, resistance r ₂The other end and resistance r ₁The other end be connected in parallel on single-pole double-throw (SPDT) range selector K ₁* 0.1 range contact, range selector K ₁Normally closed contact be connected with the setting resistance R N hot end of 421 Ω; Voltage measuring apparatus is used to connect measured " U _X" two terminals, anodal terminal is connected with I measuring disk the 19th contact, the negative pole terminal is by galvanometric change-over switch K ₂Be connected with IV measuring disk the 0th contact.

By above technical scheme, the measuring disk that four step discs are used for measure portion connects with lead, and contact resistance and variation be not in measuring the loop, and the just voltage measuring apparatus work loop of influence always hinders, because total resistance resistance is very big, so variation can be ignored; Owing to saved bracket panel, make apparatus structure simple, resistance on measuring disk and the replacement dish all is designed to 10 integral number power, the error of indication of this resistance can be compared with measuring resistance on electric bridge, can improve the resistance precision on the apparatus measures dish, manufacturing brings convenience to instrument for this, thereby and has also improved the measurement accuracy of voltage measuring apparatus complete machine.

Description of drawings

Fig. 1 is a kind of schematic circuit of the present utility model.

In Fig. 1, the adjustable resistance R of 20 * 15 Ω _P1Expression adjustable resistance R _P1Resistance by 20 15 Ω is formed, and in like manner, 19 * 100 Ω represent to be made up of the resistance of 19 100 Ω, and 10 * 10 Ω represent to be made up of the resistance of 10 10 Ω, and 10 * 1 Ω represent to be made up of the resistance of 10 1 Ω.

Embodiment

Among the figure, when four step discs all during reset, left side resistance value between node A, B equals (1900+100)/2 Ω+100 Ω=1100 Ω, the right resistance value between node A, B equals Ω+395 Ω=11000 Ω of 10450 Ω+100 Ω+(100+10)/2, therefore, between node A, B flow in 10/11 left side of total current, flows in 1/11 the right.When each step disc was put other contact, the resistance that measuring disk increases in each step disc equaled the resistance that the replacement dish reduces, so the resistance value on the left side and the right is constant between node A, B.

When * 1 range, all-in resistance is 1000 Ω between node A, B, and resistance is by 10 times of resistance r to self resistance between node A, B ₁With resistance r ₂Resistance after series connection institute is in parallel, flows through therefore that electric current is 10/11 of a voltage measuring apparatus total current between node A, B, flows through resistance r ₁With resistance r ₂Electric current be 1/11 of voltage measuring apparatus working current; When * 0.1 range, the resistance resistance in series r between node A, B ₂After, with 10 times to resistance r ₁Resistance and resistance r ₁Parallel connection makes resistance r ₁On electric current be 10/11 of voltage measuring apparatus working current, the electric current between node A, B is 1/11 of a voltage measuring apparatus electric current, so electric current reduces to 1/10 on the measuring disk, the amount of making limit is reduced to 1/10.

Voltage measuring apparatus standard operation electric current is 2.42mA, left side electric current is 2mA between node A, B, the right electric current is 0.2mA, left side electric current is divided into two branch roads after flowing to the contact that contacts with the II ' replacement dish brush, one the tunnel flows to the contact that contacts with II measuring disk brush through first step disc, and another road is through the II ' replacement dish brush, 2000 Ω resistance R ₁To the contact that contacts with II measuring disk brush, two branch road resistance values equate, so two branch currents all are 1mA.The right electric current is divided into two branch roads after flowing to the contact that contacts with the III ' replacement dish brush, and one the tunnel flows to the contact that contacts with III measuring disk brush through the 4th step disc, and another road is through the III ' replacement dish brush, 110 Ω resistance R ₃To the contact that contacts with III measuring disk brush, two branch road resistance values equate, so two branch currents all are 0.1mA.

At * 1 range, after the working current standardization, the I measuring disk is put n ₁, the II measuring disk is put n ₂, the III measuring disk is put n ₃, the IV measuring disk is put n ₄, K switch ₂Throw to the left side, be positioned at this moment that voltage is between two terminals of measurement:

U _X＝1×100n ₁+1×10×10+1×10n ₂-0.2×395-0.1×10×10-0.1×10×(10-n ₃)-0.1×1×(10-n ₄)(mv)

＝100n ₁+100+10n ₂-79-10-10+n ₃-1+0.1n ₄(mv)

＝100n ₁+10n ₂+n ₃+0.1n ₄(mv)

When * 0.1 range, the indicating value expression formula on four step discs is U _X=10n ₁+ n ₂+ 0.1n ₃+ 0.01n ₄(mv)

The electromotive force of every series-produced standard cell disperses, and between 1.0188V～1.0196V, standardized working current is 2.42mA, and therefore setting up resistance R N gets 421 Ω, adds the lockable adjustable resistance R of 0～0.5 Ω _P3, variation range that can the coverage criteria cell emf.

Electromotive force was about 1.65V when dry cell was new, just abandon when following to 1.4V with old, can both make the working current of voltage measuring apparatus be adjusted to standardization in order to make dry cell under new, former affection condition, the voltage measuring apparatus operating voltage is 4.5V, adopt three groups of dry cell series connection, get adjustable resistance R _P1Be 20 * 15 Ω, adjustable resistance R _P2Be 0～18 Ω and one the 405 Ω resistance R of connecting ₀

Internal attachment standard is calibration like this: at " U _x" two of two ends measure terminals and connect 2V normal voltage signal, K switch by polarity ₂Throw to the left side, the measuring disk indicating value is identical with standard voltage value, regulates resistance R by regulating working current _P1And R _P2, make the galvanometer nulling, again with K switch ₂Throw to the right, the electromotive force of unsaturated standard cell disperses when dispatching from the factory in factory, and between 1.0188～1.0196V, sampling is 421 Ω with the resistance of setting up resistance R N, and 0～0.5 Ω adjustable resistance R has connected _P3, regulate adjustable resistance R _P3, make galvanometer nulling once more, again with K switch ₂Throw to the left side, regulate adjustable resistance R _P2, make the galvanometer nulling, again with K switch ₂Throw to the right, regulate adjustable resistance R _P3, make the galvanometer nulling, work as K switch ₂Throw to the left side and throw when the equal nulling of galvanometer is not regulated on the right, the working current of account for voltage measurement mechanism is promptly set up ohmically pressure drop and is equated with the electromotive force of unsaturated standard cell EN, at this moment with adjustable resistance R with regard to standardization _P3Locking, this voltage measuring apparatus is from now on just as standard.

Claims (1)

1. voltage measuring apparatus, electric current from voltage measuring apparatus 4.5V working power anodal through the resistor network on four step discs between node A, the B and range transfer resistance to single-pole double-throw (SPDT) range selector K ₁Reach 421 Ω setting resistance R N and range of adjustment at the lockable adjustable resistance R of 0～0.5 Ω _P3, again to the resistance R of 405 Ω ₀, the adjustable resistance R of 0～18 Ω _P2Adjustable resistance R through 20 15 Ω resistance compositions _P1Get back to the working power negative pole and form the work loop of voltage measuring apparatus; From standard cell EN positive pole through being connected to galvanometer G double-point double-throw switch K between two normally closed contacts ₂, to setting up resistance R N and lockable adjustable resistance R _P3, arrive the standard cell negative pole again and form the voltage measuring apparatus standard loop; It is characterized in that first step disc between node A, the B is by each I measuring disk and the I ' replacement dish of being made up of 19 100 Ω resistance, the brush of I measuring disk is communicated with the brush of the I ' replacement dish, second step disc passes through 2000 Ω resistance R by each II measuring disk and the II ' replacement dish of being made up of 10 10 Ω resistance between the brush of the brush of II measuring disk and the II ' replacement dish ₁Connect, the 3rd step disc passes through 110 Ω resistance R by each III measuring disk and the III ' replacement dish of being made up of 10 10 Ω resistance between the brush of the brush of III measuring disk and the III ' replacement dish ₃Connect, by IV measuring disk and the IV ' replacement dish that 10 1 Ω resistance are formed, the brush of IV measuring disk is communicated with the brush of the IV ' replacement dish the 4th step disc by each; Be divided into two branch roads behind the anodal connected node A of voltage measuring apparatus working power: left side branch node A connects the II ' replacement and coils the 10th contact, the II ' replacement is coiled the 0th contact and is connected the I ' replacement and coil the 19th contact, I measuring disk the 0th contact connects II measuring disk the 10th contact, II measuring disk the 0th contact connected node B; The right branch node A is by 10450 Ω resistance R ₂The back connects the III ' replacement and coils the 0th contact, and the III ' replacement is coiled the 10th contact and connected the IV ' replacement and coil the 0th contact, and IV measuring disk the 10th contact connects III measuring disk the 0th contact, and III measuring disk the 10th contact is by 395 Ω resistance R ₄Back connected node B; 1000 Ω resistance r ₁An end and voltage measuring apparatus working power anodally be connected Node B and 9000 Ω resistance r ₂An end be connected in parallel on single-pole double-throw (SPDT) range selector K ₁* 1 range contact, resistance r ₂The other end and resistance r ₁The other end be connected in parallel on single-pole double-throw (SPDT) range selector K ₁* 0.1 range contact, range selector K ₁Normally closed contact be connected with the setting resistance R N hot end of 421 Ω; Voltage measuring apparatus is used to connect measured " U _X" two terminals, anodal terminal is connected with I measuring disk the 19th contact, the negative pole terminal is by galvanometric change-over switch K ₂Be connected with IV measuring disk the 0th contact.

Images