Flowserve NRR 2-40 - Manual (Page 13)

13
■ Switchpoint 1: 80 %
■ Switchpoint 4: 20 %
The level controller features the following factory set default values:
■ Relay with de-energizing delay switchpoint 1: 3s
■ Relay with de-energizing delay switchpoint 4: 3s
■ Baud rate: 250 kb/s
■ Proportional band X
P
: 20 %
■ Node ID: 040
100 %
80 %
60 %
40 %
20 %
Fig. 7
Basic Adjustments
– continued –
Factory setting
20 %
0 %
The controller type 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.
It is possible to control electric and pneumatic actuators. The control of electric
actuators is accomplished by an analogue signal which, in combination with an
active position feedback coming from the valve, is converted in the controller into a
three-position stepping signal. The control pulses for the electric actuator are
transmitted by a relay incorporated in the controller.
The control of pneumatic 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
values:
X
P
> large permanent deviation, valve reacts sluggishly
X
P
< no permanent deviation, valve may be hunting
recommended X
P
value 30 % – 100 %.
Controller NRR 2-40