Temperature sensors

Temperature sensors come in different brands, types, sizes and designs. That is why it can sometimes be difficult to find the right temperature sensor you need. Koelonderdelen.nl is happy to give you a hand!

The most important part of the sensor is the sensor, as it converts a temperature reading into an electrical signal for a controller, such as a thermostat. The rest of the temperature sensor is only there to let this sensor do its job. You should think of the connections, handles and protection tubes and everything else that has provided the wide variety of temperature sensors.

Resistance thermometers: which one do I need exactly?

The refrigeration industry mainly uses resistance thermometers. Especially the Pt100 and Pt1000 measuring resistors are very common. No less than 70% of all industrial temperature measurements are carried out with a Pt100. This is due to the large measuring range and long service life.

Pt is the abbreviation for Platinum, of which the resistance wire is made in the measuring resistor. The number after the abbreviation indicates what resistance level the sensor has. The higher the number, the higher the resistance and thus the accuracy of the measurement. A Pt100 has a resistance of 100 ohms at 0 ° C and a Pt1000 resistance thermometer of 1000 ohms at the same temperature. When the sensor detects a temperature rise, its PTC (Positive Temperature Coefficient) resistance also rises.

In addition to the PTC resistor, there is also an NTC resistor. The NTC (Negative Temperature Coefficient) resistance decreases as the temperature increases.

Two-wire connection, three-wire connection or four-wire connection

When measuring resistance with a Pt100, there may be an influence on the temperature on the connection wires, which can make the measurement inaccurate. Various solutions are available to neutralize this influence: two-wire, three-wire and four-wire connections.

The two-wire connection (white-red or brown) is the most old-fashioned solution of the three. Both wires are short-circuited during adjustment, after which a potentiometer adjusts the resistance of the pipes. After this, the measuring resistor is put back in the pipe. The temperature change on the pipe is therefore not compensated with this option.

Then the three-wire connection (white-white-red or green-white-brown): this is the most common system. The first and third wires of the Pt100 are used to determine the resistance of the Pt100 and the line resistance. Only the line resistance is determined between connection wire 1 and 2. If you subtract the answer of the second measurement from the answer of the first measurement, the resistance of the Pt100 remains.

Finally, the four-wire connection (white-white-red-red). This is ideal when you are taking measurements that require a high degree of accuracy. Two wires provide current through the sensor and two other wires carry the measurement voltage from the Pt100 to the measuring equipment. Due to the high impedance of the measuring instrument, line losses can be eliminated.

The length and material of the cable

The cable is of course also important, both the material and its length. A long cable is a godsend in hard-to-reach or passable places. The Koelonderdelen.nl range includes temperature sensors with cables up to 20 meters in length!

But the material the cable is made of can also be important. There are cables made of PVC, Silicone, Teflon, etc.

Versions and applications

In addition to the measuring resistance and the wiring, there are other influences that influence the choice of a particular version. Below are some examples:

Waterproof (WP)

In a humid environment, the watertightness of a temperature sensor may be necessary.

Housing

Some temperature probes require a protective tube, or a flame-resistant or explosion-proof housing.

Connection

There are temperature sensors with connection cables, plug connections, screw connections, etc.

Applications

Temperature sensors have also been developed for special applications. For example, there are bulb sensors, needle probes, frozen meat sensors, channel sensors, etc.

Custom made

Can’t find the temperature sensor for your application? We have access to various manufacturers, such as VDH Products, so challenge us!

Why Koelonderdelen.nl?

Thanks to the refrigeration parts from Koelonderdelen.nl, you can do periodic maintenance and repairs to your refrigeration system yourself: cheap, easy and fast! Compare our prices and delivery times with those of your refrigeration service company and be surprised!

Can we help you find a suitable solution for your refrigeration problem? We are happy to help!