Rockwell-automation 1771-IR Series D RTD Input Module User Manual Uživatelský manuál stáhnout pdf (Strana 66)

2 and 4–Wire RTD SensorsE–2

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Three–wire and 4–wire sensors compensate for lead resistance error.

Their schematic representation is shown below. The amount of error

elimination depends upon the difference between the resistance

values of the lead wires. The closer the resistance values are to each

other, the greater the amount of error that is eliminated.

Connections for 3 and 4–Wire Sensors







3-Wire Sensor







 

4-Wire Sensor

There are several ways to insure that the lead resistance values match

as closely as possible. They are:

• use heavy gauge wire (16–18 gauge)

• keep lead distances less than 1000 feet

• use quality cable that has a small tolerance impedance rating.

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Rockwell-automation 1771-IR Series D RTD Input Module User Manual Uživatelský manuál Strana 66