GESTRA NRR 2-40 - Basic Settings - Parameter Defaults; Default Factory Settings List; Controller Operational Principles

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Basic Settings – continued –
The level controller features the following factory set default values:
n Relay deenergizing delay, switchpoint 1: 1s
n Relay deenergizing delay, switchpoint 4: 1s
n Relay deenergizing delay, switchpoint 1: 3s
n Relay deenergizing delay, switchpoint 4: 3s
n Baud rate: 250 kb/s
n Proportional range X
P
: 20 %
n Node ID: 40
n Switchpoint 1: 80 %
n Switchpoint 4: 20 %
n Dead band: 0 %
Fig. 12
Factory setting
The controller NRR 240 is specially designed for level control in steam boilers and feedwater
deaerators. The NRR 240 is a proportional controller with steadystate deviation.
The positive and negative deviation lies within the proportional band (X
P
) preselected by the user.
If is possible to control electric and pneumatic (optional) actuators.
The control of electric actuators is effected by an analogue signal which, in combination with an ac
tive position feedback coming from the valve, is converted in the controller into a threeposition step
ping signal. The control pulses for the electric actuator are transmitted by the relay integrated in the
controller.
The control of pneumatic valve actuators is effected by an analogue signal 4 – 20 mA. The analogue
signal is transmitted directly from the proportional controller to the positioner of the pneumatic control
valve, which means that an active position acknowledgement is not possible.
X
P
Werte:
X
P
> large permanent deviation, valve reacts sluggishly.
X
P
< no permanent deviation, valve may be hunting, recommended X
P
value 20 % to 60 %.
Function of the controller
1/80 %
2/60 %
3/40 %
4/20 %
20 %
100 %
0%