System Description
Use level controller type NRR 2-40 in combination with
level electrode type NRG 26-40 for level control and monitoring.
The level controller has the following functions:
? Two level limit values with one switchpoint each
(HIGH-LEVEL alarm, LOW-LEVEL alarm)
? Three-position or modulating control within a
predefined proportional band
? Water level is maintained within the control band
defined by the two preset limits
The NRR 2-40 features optional outputs for standard signals
4 – 20 mA.
The level data are transferred from the electrode to the
level controller or an additional system component via a
CAN data bus. The controller and the electrode use the
CANopen protocol.Function
At regular intervals the level electrode NRG 26-40 sends
a data telegram to the level controller NRR 2-40. The data
are transferred via a CAN bus to DIN ISO 11898 using
the CANopen protocol. The transmitted data are then
evaluated and allocated to the respective control range and
switchpoints. Optionally a standard signal 4 – 20 mA is
established for external level indication or, when used for
modulating control, for the manipulated variable Y. A relay
de-energizing delay can be set manually with the control
terminal and display unit URB 1.
To guarantee the correct functioning and safety of the system
the data transmitting cycle of the level controller is constantly
monitored. When the CAN bus line is interrupted the level
switch sends a visual signal to indicate a malfunction and
the relays 1 and 4 will be instantaneously de-energized (fail
safe position).