Temperature sensor

How many metres can the cable from the PT1000 temperature sensor be extended to?

The cable of the PT1000 immersion or contact sensor can be extended up to 300 m if required. This is safe from an electromagnetic compatibility point of view.

The resulting overall (cable) resistance from cable cross-section, cable length and connection (e.g. WAGO terminal) influences the temperature measurement of the PT1000.
The larger the selected cable cross-section, the lower the overall cable resistance for the outgoing and return lines.
The overall resistance of the cable can be compensated for by an adjustable temperature correction value.

NOTICE

notice

Set a temperature correction value to compensate for the electrical resistance if the cable length is more than 5 m.

If the PT1000 cable is extended with another cable, Wilo recommends the WAGO connection terminal type WAGO 221-2411.

How is the temperature correction value determined for a cable extension?

Option 1, if exact temperature measurement is not required, carry out the following steps:

  1. Measure the actual temperature on the PT1000.
  2. Read off the actual temperature on the pump in the menu → Setting → “Analogue input (AI1 or AI2) → Overview of analogue input” (current value).
  3. Determine the delta in Kelvin from both values (measure minus read off).
  4. Enter this delta as correction value (offset) in the menu → “Set analogue input (AI1 or AI2) → Temperature correction”.

NOTICE

notice

If the delta is positive, set a negative temperature correction value, and if it is negative, set a positive one.

After entering the temperature correction value, check whether the newly displayed “current value” corresponds to the measured temperature value on the PT1000 sensor.
If yes, correction has been successful. If not, correct until the “current value” on the module corresponds to the measured value on the sensor.

Option 2, if an exact temperature measurement is required, carry out the following steps:

  1. Immerse the PT1000 in 0 °C ice water and leave for approx. 1 minute.
  2. Read off the actual temperature on the pump in the menu “Setting” → “Analogue input (AI1 or AI2)” → “Overview of analogue input” (current value).
  3. As the temperature on the PT1000 is equal to 0 °C, the temperature reading (current value) must be entered as the temperature correction value in the following menu:
  4. Menu “Setting” → “Setting analogue input (AI1 or AI2)” → “Temperature correction”.
    The temperature correction value is entered in Kelvin.

The cable extension increases the resistance and results in a higher temperature (displayed as current value). As a result, the temperature correction value must be entered with a minus sign.

After entering the temperature correction value, check whether the newly displayed “current value” is 0 °C.
If yes, correction has been successful. If not, correct until the “current value” on the module is 0 °C.

For additional information, see the Actual value sensor configuration section.