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Important notes
Intended use
The NRR 2-50 / NRR 2-51 level controller is used in combination with NRG 2.-.. level electrodes or the
NRGT 26-1 level transmitter as a limit switch and water level controller, e.g. in steam and water boiler
systems, or in condensate and feedwater tanks. The level controller indicates when a MIN and MAX
water level has been reached, and opens or closes a control valve.
The NRR 2-50 / NRR 2-51 level controller can be combined with the NRG 21-.. or NRG 26-21 level
electrodes and the NRGT 26-1 level transmitter.
The
NRR 2-50 / NRR 2-51 level controller
processes the level-dependent voltage signals from the
NRG 2..-.. level electrodes or the level-dependent current signal from the NRGT 26-1 level transmitter.
These input signals are standardised by the controller to 0 and 100 % of the boiler measuring range,
and shown as an actual value on the 7-segment LED display.
Level controller NRR 2-50:
The level controller works with an electrically actuated control valve as a
3-position stepping controller with proportional-plus-integral control action
(PI controller)
. If the actual
value deviates from the setpoint, the electric actuator is triggered by two output contacts and two
flashing LEDs indicate whether the control valve is opening or closing.
The controller can be configured for fill or discharge control.
A further output contact indicates when a MIN or MAX water level is reached (the desired function can
be selected by a switch). After the de-energizing time has elapsed, the output contact switches over
and the MIN or MAX LED lights up.
Level controller NRR 2-51:
The level controller works with an electro-pneumatically actuated control
valve as a continuous controller with proportional-plus-integral control
(PI controller)
. In the event of
deviations from the setpoint, it outputs a current of 4-20 mA as manipulated variable Y.
The controller can be configured for fill or discharge control.
If the MIN or MAX water level is reached, after the de-energizing delay the MIN or MAX output contact
switches over in the level controller, and the MIN or MAX LED lights up.
Level controller NRR 2-50 / NRR 2-51:
Faults in the level electrode, the level transmitter, the electri-
cal connection or the settings are indicated as error codes on the 7-segment LED display. In the event
of a malfunction, the MIN and MAX alarm is triggered.
If faults occur only in the
NRR 2-50 / NRR 2-51 level controller
, the MIN and MAX alarm is triggered
and the system is restarted.
Parameters can be changed or the MIN/MAX alarm simulated by operating the rotary knob.
For external level indication, the
NRR 2-50 level controller
is optionally available with a 4 - 20 mA
actual value output.
Function
