Thermal sensors are essential elements in many control systems. The PT100 resistance thermometer is one type of instrument that can be used. There are also devices Pt-500, Pt-100, 10K. This particular type is made on the basis of platinum, but you can also find copper and nickel. In our article, we will look at the features of temperature measurement sensors.
Main features of the device
Pt100 Platinum RTD is a fairly common item as it has a very good quality/price ratio. It can be used as a separate measuring instrument. But it can be built into the sleeve of another device in order to record data on temperature changes. The main thing in this case is to correctly take into account the diameter of the sleeve so that there is no big difference in diameters. In this case, it will be possible to provide the best condition in order to analyze the temperature of the media.
Usuallysuch sensors are used to control the temperature in ventilation systems, thermal power plants, as well as other industries.
Operating principle
Based on platinum elements, whose resistance at 0 degrees is 100 ohms. It is worth noting that platinum has a positive coefficient. This means that the resistance increases with increasing temperature. For some devices, three thermocouples can be enclosed in one housing at once. But most often in the industry they use the Pt100 "Aries" thermal resistance with one element. Aries is a domestic company that manufactures and sells automation and data measurement equipment.
Depending on the type of measuring circuit, a certain connection method is used - two-, three-, four-wire. From where and for what the device is used, you can choose the most acceptable characteristic. Pt-100 RTDs can be used to measure the temperature of gases or liquids. However, it can also be used to control the temperature of products in the food industry.
These devices may be compatible with devices that have the same input impedance. The maximum temperature that the sensor can measure is about 350 degrees. But at the peak it can withstand jumps up to 400 degrees. But these are average values, they depend on the manufacturer. For some sensors, the operating range is -40..+90, for others it is already -50..+250. Butthere are also models that work in the range -100..+600.
When can't edit?
It is not allowed to install devices in the following conditions:
- If the vibration level is too high.
- High chance of hull damage.
- Corrosive chemical environment.
- Explosive atmosphere.
- In close proximity to sources of electrical interference.
Instrument Specifications
Technical features of the sensor (thermostat is taken as an example):
- The case is made of stainless steel.
- Weight – 600 gr.
- Dimensions 62x66x67 cm. The size of the direct sensitive element of the sensor is not taken into account.
- Can measure temperatures in the range of -50..+100 degrees.
- The maximum error value is 2%.
- Max power consumption is 2W.
- Humidity of the working environment is 80% at 35 degrees.
- Pressure – 0.01..1.6 MPa.
When carrying out installation work, it is extremely important to comply with safety requirements. At enterprises, the installation of these devices is carried out by persons who have undergone appropriate instruction. They must also be trained to operate the equipment. Installation, dismantling and inspection is possible only if the power is disconnected from the device.
Why do sensors break?
In total, there are three reasons why the failure occursitem:
- Operation rules violated.
- Failure of one or more relay elements.
- Weak sensor mounting.
To avoid premature failure, you need to carefully study the instructions before installation and maintenance.
How does the sensor work?
The principle of operation is not very complicated. As we said, the basis is a platinum element, which at 0 degrees has a resistance of 100 ohms. If we are talking about a sensor, for example, Pt1000, then, accordingly, it will already have a resistance of 1000 Ohm (1 kOhm). Platinum instruments have a positive coefficient, so as the temperature increases, so does the resistance.
In the figure you can see the connection of the Pt100 thermistor. We mentioned that there are several connection options - with two, three or four wires. Which one to choose is up to you. But it should be noted that the four-wire device will have the best accuracy. But if you do not need high accuracy, then it is more reasonable to use two-wire sensors.
There are also two accuracy classes - A and B. The latter is divided into two subclasses - B1 / 3DIN and B1 / 10DIN. They cannot be used on their own over the entire temperature range.
Summarize
Very often, Pt-100 sensors are used in thermal power engineering to maintain a given temperature in the measured medium. They are also often used for automatic heating control systems. This allows you to automate production andreduce system management costs.
Often, sensors are installed in underwater and underground pipelines. The product is of very high quality, which guarantees a long service life. If done correctly, of course. The characteristics of the Pt100 thermal resistance are good enough that it can be used in all areas.
The operating temperature range is large enough to be used in almost any industry. Also, the sensor can monitor the state of the air. Therefore, it can be used in warehouses and production facilities, which have certain requirements for the environment and climate. Disposal must be carried out according to the rules that apply to the processing of electrical waste.
