GESTRA NRR 2-40, Руководство по установке

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31
Establishing switchpoints and proportional range
– continued –
Commissioning
– continued –
Press button briefly.
Lower or raise the liquid level until switchpoint 1
within the control range is reached.
Press button twice briefly.
Switchpoint 1 is now saved.
The NRR 240 is now again in operating
mode.
The feedback potentiometer of an external control valve with electric actuator has to be calibrated
manually before commissioning.
1. Ascertain the total resistance of the feedback potentiometer.
2. Set the control valve manually to midposition.
3. Adjust manually the position of the feedback potentiometer until the partial resistance values of the
measured total resistance are equal.
n
For the GESTRA level controller NRR 240 a
1000
Ω
feedback potentiometer in an external
control valve is required!
n
If the terminals for the feedback potentiometer are not wired or the feedback potentiometer
is defective the NRR 240 will work as
twoposition controller
!
n
Use the control and display units URB 1 and URB 2 for semiautomatic calibration of
the feedback potentiometer of an external control valve
without
measurement of the
resistance value. If you use the URB 1 or URB 2 please refer to the operating manual for
more information.
Fig. 21
Attention
Calibrating the feedback potentiometer of an external control valve
1000 Ω +/– tolerance
Mean value
0 Ω