Ba-siemens-symaro Sensor Introduction

1 principle of the sensor

Sensor, controller, actuator is composed of 3 elements of the control system, the role of the sensor is generally used to measure the process parameters, provided to the Controller or display instrument, to achieve process monitoring or control. The type of sensor is classified according to the measurement parameters, mainly divided into temperature, pressure, level, flow, humidity and air quality in air conditioning applications is also an important category, especially humidity. According to the function of the sensor, the sensor is generally composed of 3 parts, namely the sensitive element, the conversion circuit and the measuring circuit, wherein the sensitive element is the most important part of the sensor, it not only determines the measurement performance of the sensor.

1.1 Temperature sensor

The sensitive elements of the temperature sensor are generally used in the thermal resistance mode, the common thermal resistance is Pt100, Pt1000, Ni1000. It mainly uses its temperature and resistance characteristics, that is, when the temperature changes, its resistance changes accordingly. The above-mentioned thermal resistors have a fixed temperature and resistance characteristics, generally we also known as the scale table. Another commonly used sensitive originals are thermistors with positive and negative temperature types.

1.2 Humidity sensor

Humidity is the amount of water vapor in the air, can be expressed by absolute humidity and relative humidity, wherein the relative humidity is more commonly used in practical applications, the unit is%r.h. Humidity sensor is a more widely used in air-conditioning products, currently the most used humidity sensor measuring principle of capacitance. Mainly used in building air conditioning humidity regulation and industrial production process of humidity control.

The method of absolute humidity and relative humidity is used to indicate the content of humidity in air.

Absolute Humidity: Air contains the absolute value of water vapor, unit g/kg

Relative Humidity: The actual water vapor density in the air and the percentage value of the saturated water vapor density under the same question, called the relative humidity of the air, Unit%r.h

Absolute humidity can only explain the quality of the water vapor in the humid air in the century, but not the air dry or humid Chengdu and the size of the hygroscopic capacity.

The relative humidity indicates the degree of water vapor near saturation in moist air, the value is small, the wet air saturation is small, the water vapor absorption ability is strong, the value is opposite .

Wet Bulb temperature: refers to the same enthalpy of air state, the air vapor saturation when the air temperature, in the air enthalpy wet diagram is from the air state point along the enthalpy line down to 100% RH line, the corresponding point of the dry bulb temperature.

Dry Bulb temperature: actual air temperature.

1.3 Pressure sensor

Pressure sensor is a control system in the application of a lot of process variable control parameters, the application of pressure sensing elements are more, mainly using the deformation of the object under pressure, the corresponding electrical parameter changes to measure the pressure parameters. Our sensors use ceramic resistors to measure process pressure and are relatively short in relative measurement time.

The pressure measurement object is mainly liquid, gas, the measured variable is the corresponding medium pressure, and through the pressure measurement method indirectly obtained other parameters, such as liquid level and fluid flow. Its parameter expression is divided into absolute pressure, table pressure and differential pressure, wherein the pressure of the pipe is expressed as gauge pressure or absolute pressure or differential pressure, general air conditioning duct, including indoor pressure using differential pressure expression. Pressure units are generally used MPa, kg/cm2, Bar, KPa, Pa, can be converted between units.

Several methods of expression of pressure transducer:

1. Absolute pressure: with absolute vacuum as the basis of pressure expression, also known as total pressure or full pressure, commonly used p.

2. Atmospheric pressure: pressure generated by the weight of the air column on the Earth's surface

3. Table pressure (gauge): The pressure indicated by the general pressure gauge, when the absolute pressure is greater than atmospheric pressure, it is equal to the difference of absolute pressure minus atmosphere, namely: gauge pressure = absolute pressure-atmospheric pressure

4. Negative pressure or vacuum degree (also known as air pressure): that is, the absolute pressure of the medium under test is lower than the atmospheric pressure. Vacuum degree = atmospheric pressure-absolute pressure

To a pressure unit conversion URL:

http://yali.51240.com/

1.4 Air quality sensor

Due to the requirements of comfort air conditioning and energy saving measures, as well as the requirements of special environment, indoor air quality regulation becomes more and more important. Indoor air quality CO2 and VOC, wherein the CO2 adjustment or measurement application is more, at present in the market CO2 sensor basic use of infrared light measurement principle.

degree table of the CO2 sensor

Ppm	Results
330	Standard Outdoor Concentration
1000	20% people in the room feel comfortable
1500	Limit values according to the DIN1946 standard
4000	Classroom Maximum value after class
5000	Maximum allowable value of factory
100,000	The candle goes out and loses consciousness.

2 Symaro sensor overview

The CPS sensor comes from two parts, some from the United States, and is mainly used for integration with Apogee building control systems. Another part from Europe, the origin of Switzerland, the application of a wide range of Symaro sensor is its general name. Basically covers all HVAC applications, including temperature, humidity, pressure, air quality and other types.

2.1 Temperature sensor

The Symaro temperature sensor is mainly water and air, where air is divided into indoor, outdoor and duct.

The water pipe temperature measurement range can be up to 2000C, the lowest possible to -500c, the output can choose the passive (resistive) output, as well as the active (0~10v or 4~20ma) output, can be integrated into different control systems. The installation method is divided into immersion type, clamp type and cable type, in which the clamp type and cable type can be adapted to the installation of special occasions, such as the case of relatively thin pipe. Its features are:

• External cassette sensor for easy and quick installation.

• Plug-in temperature sensor time constants are relatively short and easy to control.

• Plug-in temperature sensor temperature measurement is relatively wide, adapt to different occasions.

1. The air temperature sensor adapts to different measurement environments, including duct, indoor and outdoor temperatures, and outputs can be passive thermal resistance and active 0~10v and 4~20ma modes.
2. The duct temperature is measured by the average temperature, which shows the duct temperature more accurately.
3. The duct temperature sensor is easy to install thanks to its flexible sensor.
4. The structure design of the indoor temperature sensor avoids the influence of the wall on the sensor, and the measurement is more accurate.
5. The outdoor temperature sensor minimizes the effects of solar radiation, wind and walls on temperature measurements.

2.2 Humidity sensor

The Symaro humidity sensor is divided into 2 categories, a sensor family for standard applications in general building applications, with a accuracy of ±5% r.h and a measuring range of 0~95%r.h. High-precision type sensors adapt to high humidity requirements, such as factories, laboratories, hospitals, the measurement accuracy of ±2% r.h, measuring range of 0~100%r.h. Symaro provides a single wet and temperature-humidity composite sensor, the current temperature and humidity composite sensor applications are more. The humidity signal output mode is 0~10v and 4~20ma, the temperature signal output mode is resistance type, 0~10v and 4~20ma.

2.3 Pressure sensor

The Symaro pressure sensor is used for water and air measurement in HVAC systems. Air pressure is divided into differential pressure switch QBM81 series, mainly used for fan protection, filter detection: Differential pressure sensor QBM66 and 65 series for air duct pressure, wind speed detection and room positive, negative pressure adjustment detection, the minimum differential pressure can reach 100Pa, output for the 0~10v:qbm75 series for the relatively high accuracy of the difference Pressure sensor, the accuracy can reach 2% full scale, the output is 4~20ma.

Liquid pressure and differential pressure sensor mainly measure the medium is water, wherein QBE2002 is commonly used hydraulic pressure sensor, pressure range from 1bar~40bar, medium temperature range -40~800c, when the temperature is high, use cold water elbow to heat insulation.

2.4 Air quality sensor

Air quality sensors are commonly used in indoor CO2 sensor QPA2000 and duct CO2 sensor QPM2000, the measurement range is 0~2000ppm, the general set value of 1000ppm us, the output is 0~10v. In addition we offer CO2 and VOC, CO2 and humidity and temperature, CO2 and temperature composite air quality to meet different occasions. Our CO2 sensors use a hardware-compensated approach, with good precision stability and no recalibration for 8 years.

2.5 Other Sensors

In addition to the sensors listed above, we classify other sensors in this category, they include duct velocity sensor QVM62.1, measuring range of 0~10m/s: water pipe flow rate switch QVE1900 and QVE1901, suitable for pipeline dn32~dn200 water flow detection, many for water pump Nursing.

3 selection of sensors

The model of the Symaro sensor starts with Q and the other bits are named as defined in the table below.

In addition to considering the different measurement media, the following parameters are considered in the sensor selection:

1. The accuracy of the precision sensor indicates the degree to which the sensor's output corresponds to the measurement.

Absolute error: The difference between the measured value and the ideal value:

Relative error: The absolute error of the measured point is the ratio of the ideal value of the measured point:

Reference error: The ratio of the absolute error of the measured point to the reference value (range):

Basic error: In standard conditions, the reference error within the range of the reference value (range):

Linear error: The deviation between the measured curve and the ideal line:

Linearity: The linear error limit of the sensor.

2. Measuring range and range within the allowable error limits, the ranges between the lower and upper limits of the measured values are called measuring ranges. The general selection of the project is rated at the middle or 2/3 of the measuring range.

3. The method of measuring sensor operation is also an important factor to be considered when selecting the sensor. For example, contact and non-contact measurement, destruction and nondestructive measurement, online and non-online measurement, etc.

4.IP Protection class

IP Protection rating refers to the level of dust-proof, moisture-proof electrical equipment, and the environment. 5. Signal output signal output is the same as the controller or digital equipment electrical connection characteristics.

4 Supporting documentation

4.1 sensor selection software SESP

SESP is an information platform for HVAC sensors, including product documentation, including datasheet. At the same time, you can also enter the old model, you can automatically go to the new model of the interface, and display the corresponding information. It is a useful search tool to quickly find the type of sensor you need, while the note can be linked to the appropriate technical documentation and installation instructions. Of course, you can also enter the sensor model (ASN) you know directly to get the relevant information.

4.2 S y Maro Products in the book

Ba-siemens-symaro Sensor Introduction