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Products－Industrial temperature sensor－Assembling type RTDs－Types, tolerance and wiring method
Type of resistance thermometer sensor．
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Nominal resistance value at℃
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Class
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Measuring current
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R(100℃) / R(0℃)
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Pt100
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A
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Below 2mA
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1.3851
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B
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Note
1. R(100℃) is the resistance value of the sensing resistor at 100℃.
2. R(0℃) is the resistance value of the sensing resistor at 0℃.
Tolerance of resistance thermometer sensor and applicable standard table
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IEC 751
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JIS C 1604
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Class
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Tolerance (℃)
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Class
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Tolerance (℃)
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Pt100
( R(100℃) / R(0℃)=1.3851
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A
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±（0.15 +0.002|t|）
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A
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±（0.15 +0.002|t|）
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B
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±（0.3+0.005|t|）
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B
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±（0.3+0.005|t|）
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Note．
1．Tolerance is defined as the maximum allowable deviation from the temperature vs resistance reference table．
2．l t l=modulus of temperature in degrees Celsius without regard to sign．
3. Accuracy class 1/n(DIN) refers to 1/n tolerance of class B in IEC 751
Wiring method of resistance thermometer sensors
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Two-conductor type：
Since a conductor resistance is added to the resistance value. It is necessay to reduce the conductor resistance in advance. This type is not usually used except for a high resistance RTDs.
Three-conductor type:
Use to eliminate the effect of conductor resistance. Care should be taken for long distance transmission because a variation of resistance of conducto rs has an effect on accuracy. This type of connection is most widely used in industrial applications.
Four-conductor type:
This connection is used for high-accuracy measurement and standards because it is not affected by conductor resistance. Generally, a constant current is applied and the resistance value is measured by a potential difference.
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