YM:PT100

Platinum resistance thermometers offer excellent accuracy over a wide temperature range (from -200 to 850 °C). Sensors are interchangeable between different manufacturers, and are available in various accuracy ratings and packages to suit most applications. Unlike thermocouples, it is not necessary to use special cables to connect to the sensor.

1 Connection

1.1 Four-wire Circuits

The four-wire technology provides ideal connection possibilities for resistance thermometers. The measurement result is not affected by impedance or temperature-related fluctuations. Cable compensation is not required. The sensor receives the measuring current through the cable. The voltage-drop is tapped off by the measuring lines. If the input resistance of the downstream electronics is much higher than the output impedance, it can be neglected. Thus, the determined voltage-drop is independent of the cable characteristics.

1.2 Three-wire Circuits

The three-wire technology also works with two measuring circuits, one of which is used as a reference. Because of the three-wire circuit the amount of the impedance as well as its temperature dependence can be compensated. However, it is required that all three cores have identical properties and are subject to the same temperature conditions. Since in most cases this is true, the three-wire technology is the one most frequently used these days. Cable compensation is not required.
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1.3 Two.wire Circuits

Evaluation electronics and temperature probe are connected by a two-core cable. Like any other electrical conductor this cable has a resistance which is in series with the temperature sensor. These two resistances are added, and the result is a systematically higher temperature reading. To prevent this error the resistance of the cable (called offset) must be subtracted from the measurement result. This offset value can be input in the most evaluation systems where the impedance is taken into account.

2 Calibrated / Measured PT100 for Thermaloil

On Line where calibrated PT100 are used, the offset of the PT100 have to be calculated and entered. Please use for this the excelsheet under Template:PathRelPublicTemperatures\PT100-Offset-Calculation.xlsx

3 Test Procedure

Test: confirm with calibrated measurement equipment, that temperature indicated in PVSS is correct. (Maximum allowed tolerance of 0.5°C)

Manufactured acc. DIN EN 60751
Class B = ± (0.30 °C + 0.005 · T)

Check the thermometer for proper operation by means of an ohm-meter. At an ambient room temperature of approx. 20°C the resistance must be approx. 109 ohms and must increase when heated up.
Connect the measuring line according to the circuit diagram. Make sure that the maximum operating temperature is not exceeded.

Definition