Gestra NRR2-40 Level Controller

Issue Date: 10/06
GESTRA Steam Systems
Product Range B1
Level Controller Type NRR 2-40 With CAN-Bus
NRR 2-40
System Description
CAN Bus
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.
All level and temperature switches, controllers and electrodes are interconnected by means of a CAN bus. The data
exchange is effected by means of a CAN bus according to
DIN ISO 11898 using the CANopen protocol. Every item of equipment features an electronic address (Node ID).
The four-core bus cable serves as power supply and data highway for high-speed data exchange.
NRR 2-40 is configured at our works and ready for service with other GESTRA components.
NRR 2-40 can be used straight away without having to set the node ID.
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 con­
troller 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).
Design
NRR 2-40 b Enclosure of insulating material with terminals for installation in control cabinets. The terminals are externally accessible. Clipping onto a 35 mm standardized supporting rail
(DIN EN 50022). External dimensions: 100 x 73 x 118.
Technical Data Type approval no.
TÜV . WR · 03-399 Input Interface for CAN bus to DIN ISO 11898, CANopen protocol
Feedback potentiometer 1000 Ω.
Output Power supply 24 V DC, conditionally short-circuit ­protected.
Analogue output 4 – 20 mA, load 500 Ω for display of actual value (option).
4 volt-free relay contacts.
Max. contact rating with switching voltages of 24 V AC, 115 V AC and 230 V AC:
4 A ohmic, 0.75 A inductive at cos ϕ 0.5 Max. contact rating with a switching voltage of
24 V DC: 4 A.
Contact material: silver, hard-gold plated Interference suppression Provide contactor with external RC combination
(100 Ω-47 nF) or according to the specification of the valve manufacturer.
Analogue control output for manipulated variable 4 – 20 mA, max. load 500 Ω (option).
Relay de-energizing delay Output “min”, “max” 3s (set at the factory).
P.T.O.
Important Note Note that screened multi-core twisted-pair control cable is required, e. g. UNITRONIC® BUS CAN 2 x 2 x ...2 or
RE-2YCYV-fl 2 x 2 x ...2. The bus lines in the control cabinet must be used up to the control devices.
The baud rate (data transfer rate) dictates the cable length between the bus nodes and the total power consumption
of the sensor dictates the conductor size.
S8
S9
S 10
OFF
ON
OFF
Baud rate
Cable length
250 kBit/s
125 m
Factory setting
Number of pairs and conductor size [mm2] 2 x 2 x 0.34
ON
ON
OFF
125 kBit/s
250 m
2 x 2 x 0.5
OFF
OFF
ON
100 kBit/s
335 m
2 x 2 x 0.75
ON
OFF
ON
50 kBit/s
500 m
OFF
ON
ON
20 kBit/s
1000 m
ON
ON
ON
10 kBit/s
1000 m
on request, dependent on bus configuration
The baud rate is set via a code switch. Reduce baud rate if cable is longer than specified in the table. Make sure that
all bus nodes have the same settings.
To protect the switching contacts fuse circuit with 2.5 A (anti-surge fuse) or according to TRD regulations (1.0 A for
72 hrs operation).