Weighing sensor principle

1. What is the weighing sensor?

Weighing sensor is used to weight signal and pressure signal is converted into electricity signal conversion device.

2. Weighing sensor principle is what?

Weighing sensor of using metal resistance strain gauge measuring bridge road, use metal wire stretched out in the tension

Long and the principle of resistance increase, namely metal resistance varies with the effect of variation in the strain and made of (strain,

Is the size of the change).

3. The structure principle of weighing sensor?

Metal resistance with obstacles to the nature of the current flow, namely with the resistance (Ω), its resistance varies depending on the species of metal.

The same kind of metal wire, in general, the more elongated, the greater the resistance value. When metal wire by outside force

With the scale, its resistance value will increase or decrease in a certain range. As a result, the metal wire (or film) close to being

Measuring objects, and the wire or membrane and it's fine or thin, paste is very perfect, so, when the object to be tested

Scale by external force, the metal wire (film) will be in proportion to scale, its value will change accordingly. weighing

Sensor is the metal resistance strain gauge paste on the metal weighing beam to measure the weight signal.

4. The appearance of weighing sensor structure and measuring weight form?

The appearance of the weighing sensor of measured object with different structure, its shape will be different.

A. the appearance of more common weighing sensor structure:

Pillar; S type; Spokes; Ring type; Disc; Box, etc.

B. weight measurement form:

Normal stress measurement (column type, single point, etc.), shear stress measurement (double shear beam, part of the S type, and spokes, etc.)

And can be divided into pressure type (column type, disc type, etc.), pull (part S type sensor, ring type sensor), tension and compression

(part of the pillar, and spokes, S type, etc.)

C. elastic element of the internal strain beam structure forms:

Parallel beam, shear beam, etc

D. objects: the application of different structure forms of sensor

Pillar - the large-tonnage truck scale, scale, hopper scale, material tank scale, testing machine, a strength monitoring and measurement, etc.;

S - used to hopper scale, material tank scale, packing machine, packaging weighers, material testing machine, etc.;

Double shear beam, truck, rail weighbridge, etc;

Single point - scales, pricing scales, counting scales, platform scale, industrial field weight control and measurement;

5. Weighing sensor circuit composition?

Weighing sensor to measure, we need to know is the resistance of the strain gauge under load changes. usually

Using strain gauge bridge circuit (wheatstone bridge), will cause the resistance strain gauge change into a voltage change

To measure.

Set: the bridge of the input voltage of Ei, the bridge output voltage of the delta E0 is: delta E0 = Ei x [(R1R3 -

R2R4)/(R1 + R2) (R3 and R4)]

The bridge of the initial conditions for R1 = R2 = R3 = R4, the delta E0 = 0.

A resistance strain gauge of R1 by strain effect of changes in resistance to R + delta R, then the output of the bridge

Pressure delta E0 is: delta E0 = Ei [delta R/(4 R + 2 delta R)] ≌ Ei (delta R / 4 R) (R > > delta R)

Due to the delta R = R * epsilon K0, so delta E0 = (Ei * epsilon K0) / 4

For example, set K0 = 2, epsilon = 1000 x 0.000001, Ei = 1 v

Is: delta E0 = (1 x 2 x 1000 x 0.000001) / 4 = 0.5 mV

Type of coefficient K0 = (generally 2) as in

Epsilon = strain coefficient (general for 500 x 0.000001 ~ 2000 x 0.000001; equivalent

10 ~ 40 KGF/was. )

Ei = input excitation voltage

In order to increase the apparent output of the bridge, most of the bridge design into 4 pieces of strain gage are the stress function of the form (4

A work piece).

The delta E0 = 0.5 mV * 4 = 2 mV

6. The output of the sensor sensitivity of representation?

The change in the sensor response (output) to the appropriate incentives than (load) changes. The output of the sensor in spirit

Acuity with rated load state of bridge of the ratio of output voltage and input voltage (mV/V).

Often refer to the output sensitivity of the transducer.

7. Why should sensor internal compensation circuit?

Weighing sensors in the manufacturing process, in order to improve its performance, especially to improve the temperature characteristic, want to be in commonly

Strain gage circuit attached to zero and sensitivity temperature compensation. That in addition to strain gauge, which also increased

All kinds of compensation resistance.

The purpose is to minimize a bridge zero zero compensation along with the change of temperature, as a result, in addition to the temperature of the strain gauge itself

Since the compensation, and joined the temperature coefficient of resistance and bridge strain gauge the temperature coefficient of different resistance element

(such as copper resistance or nickel resistance, etc.), to strengthen the compensation effect.

Sensitivity of compensation is the purpose of reducing the output voltage with the change of temperature, the compensation of elastomer elastic coefficient and should be

Change of sensitivity coefficient changes with temperature. Therefore, the bridge in the combination of the two and bridge temperature compensation

With the same resistance. At the same time other resistance in the circuit is used to bridge the initial balance, rated output and input

Resistance parameters, such as adjusting to the specified value.

8. The parameters of the weighing sensor () in both Chinese and English

9. A particular judgment method of the function of the weighing sensor wire

Due to different manufacturers sensor wire color is different, so can't judge lead work with specific colors

Can.

Resistance can be used with a multi-meter specific judgment function lead:

Before (see photo)

(1) - (2) the excitation voltage input end (hereinafter referred to as the input)

(3) - (4) the weight of the millivolt signal output (output)

Model: on STC - 100 kg (specifications)

Cap: 100 kg (range)

Date: 2007-05-28 (production Date)

S/N: 123456 (factory number)

FSO: 2.9981 mV/V (sensitivity)

It Excitation: 10 v AC/DC Excitation voltage (Recommended)

Maximum Excitation: 15 v AC/DC (Maximum Excitation voltage)

The Output at Rated Load: 2.9981 mV/V (Output Rated Load)

Non Linearity: < 0.020% (nonlinear)

Hysteresis: < 0.020% (lag)

Creep (30 minutes) : 0.029% Creep (30 minutes)

Non Repeatability: < 0.01% (routine)

Zero Retum (30 minutes), 0.030% (30 minutes) Zero drift

Temp. Effect / ℃ on Span: < 0.015% (1 ℃ temperature change range

The influence of)

Temp. Effect / ℃ on Zero: < 0.0026% (1 ℃ temperature change to Zero

The influence of)

Compensated Temp. Range: 10 to 40 ℃, temperature compensation Range),

Operating Temp. Range: - 20 to 60 ℃ (working temperature Range),

Zero Balanc: plus or minus 1% (Zero balance)

Input to hold: 380 + 5 Ω (Input impedance)

The Output to hold: 350 + 3 Ω (Output impedance)

Insulation

To hold (50 VDC) :

> 5000 m Ω (insulation resistance)

Safe phrase: 150% (safety Overload)

Ultimate phrase: 300% (Overload limit)

Lead measurement data function

(1) - (2) 380 + 5 Ω input

(3) - (4) 350 + 3 Ω output

Note: if the data are not equal, suggests that the sensor has been damaged, should be replaced.

(1) - (3) (1) - (4) 300 + 3 equal Ω numerical bridge balance

(2) - (3) (2) - (4) 300 + 3 equal Ω numerical bridge balance