How to select sensors

1. Determine the requirements of the sensor

Measuring range: the measuring range is an important factor of the sensor. If the measuring range is too small, it is easy to overload and the sensor will be damaged. If the range is too large, the measurement accuracy can not meet the requirements. Generally, the range of the selected sensor is 10%~30% larger than the upper limit of measurement, depending on the specific situation.

Output signal: Weighing force sensor is generally divided into analog output sensor and digital output, and the conventional output is mV analog signal.

Force direction: the conventional sensor force direction has pull, press and pull-press two-way direction.

Elastomer materials of sensors: there are three kinds of common materials: aluminum alloy, alloy steel and stainless steel. The overload resistance and natural frequency of different materials are different.

Installation size: Different practical applications have different requirements for the size of sensors. Conventional sensors include single-point sensor, S-type sensor, cantilever beam sensor and spoke sensor.

Accuracy: Accuracy is an important performance index of the sensor. Generally, the higher the accuracy, the higher the cost, so it should be reasonably selected according to the whole measurement system.

Sampling frequency: Dynamic measurement and static measurement are common, and the sampling frequency determines the choice of sensor structure.

Environmental factors: humidity, dust index, electromagnetic interference and so on.

Other requirements such as wire specifications, cost considerations, etc.

2. Understand the main parameters of the sensor

Rated load: refers to the maximum value that can be measured within the specified technical index range when designing this sensor.

Sensitivity: the ratio of output increment to added load increment. Usually, it is rated output mV per input voltage of 1V.

Resolution: The minimum weight (force) change that can be detected by the sensor.

Zero output: the output of the sensor under no load.

Safety overload: the maximum allowable load without permanently shifting the sensor parameters. Generally expressed in proportion to the rated range (120％F.S).

Ultimate overload: the maximum weight allowed to be added without causing mechanical damage to the sensor. Expressed in proportion to the rated range.

Input impedance: the impedance measured at the input of the sensor when the output is short-circuited. The input resistance of the sensor is greater than the output resistance.

Output impedance: the impedance measured at the output of the sensor when the input is short-circuited. When sensors from different manufacturers are used in parallel, their input impedances should be the same.

Insulation impedance: Insulation impedance is equivalent to connecting a resistor with equivalent resistance between the bridge of the sensor and the ground, and the insulation resistance will affect the performance of the sensor. When the insulation impedance is lower than a certain value, the bridge will not work normally.

Excitation voltage: generally 5~10 volts. This is because the regulated power supply in general weighing instruments is 5 or 10 volts.

Applicable temperature range: The applicable occasions of this sensor are specified. For example, the normal temperature sensor is generally labeled as -10℃~60℃.

Connection mode: Generally, there will be detailed connection instructions in the product description.

Protection grade: used to indicate the dustproof and waterproof grade, and whether it is protected against general corrosive gases and corrosive media.

3. Choose the right sensor

After the requirements and main parameters of the sensor are determined, the appropriate sensor can be selected. In addition, with the development of sensor manufacturing technology, in order to meet the needs of different applications, customized sensors become more and more