IM-P343-37 CTLS Issue 4
38
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TRANSLATION RUN OVER
SP400 Electropneumatic Smart Positioner
9.5.3 dbANd - deadband setting (positional sensitivity)
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Programming notes
Dead-band provides adjustment of the valve positioning sensitivity relative to the input signal and is expressed
as a % of the input signal span.
Default value based on a 4 - 20 mA input signal span is 0.5%. To alter the displayed value press
the and keys. Press the key to accept the displayed value and advance to split range.
Commissioning notes
Setting a narrow deadband may induce oscillations of valve movement caused by fluctuations in
the input signal, high stem friction or operating at low ambient temperatures below 0°C. Setting a
wider deadband will dampen out oscillations but may cause an inaccuracy in actual valve position.
This effect will increase if valve travel is limited. It is normally recommended that the default value
is used. If necessary increase the % value to dampen out any oscillations in valve movement. This
may be necessary for valves having graphite packed stem seals or smaller size actuators.
9.5.4 Split range
This menu can change the range. 3 values are allowed: OFF, LOW and HIGH.
OFF (range 4 - 20 mA)
4 mA corresponds to the minimum of the stroke 0%
20 mA corresponds to the maximum of the stroke 100%
LOW (range 4 - 13 mA)
4 mA corresponds to the minimum of the stroke 0%
13 mA corresponds to the maximum of the stroke 100%
HIGH (range 11 - 20 mA)
11 mA corresponds to the minimum of the stroke 0%
20 mA corresponds to the maximum of the stroke 100%
To alter the displayed value press the and keys. Press the key to accept the displayed value and
return to SET.
Commissioning notes
This function is used when 2 positioners are on the same current loop. One set to LOW, the other
set to HIGH. When the current rises beyond 11 mA, the second valve starts to open giving its
contribution to the overall ow. A single current signal drives 2 valves.
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