Flowserve NRG 26-40 - Manual (Page 5)

5
Explanatory Notes
continued
Description
The level electrode NRG 26-40 works according to the capacitance measurement principle.
The NRG 26-40 is used for signalling different levels in conductive and non-conductive liquids:
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Water level maintained within the control band defined by two preset limits.
Use level electrode NRG 26-40 in combination with level switch type NRS 2-40 or further system
components. The level data are transferred to the level switch or another system component via the
CAN data bus, adopting the CANopen protocol.
System components
NRS 2-40
Digital switching controller for level electrodes type NRG 26-40.
Functions: Four liquid levels with one switchpoint each, MAX alarm, MIN alarm, pump ON, pump OFF
with one switchpoint each, water level continuously within the predefined control band.
Data exchange: CAN bus to DIN ISO 898, using CANopen protocol.
NRR 2-40
Digital level controller for level electrodes type NRG 26-40.
Functions: Four liquid levels with one switchpoint each, MAX alarm, MIN alarm, pump ON, pump OFF
with one switchpoint each, water level continuously within the predefined control band.
Data exchange: CAN bus to DIN ISO 898, using CANopen protocol.
URB 1, URB 2
Control terminal & display unit.
Functions: Parameterization and visual display (LCD).
Data exchange: CAN bus to DIN ISO 898, using CANopen protocol.
Design
NRG 26-40:
Screwed design ¾" BSP, EN ISO 228-. Fig. 2
Function
The principle of capacitance measurement is applied to determine the level.
The electrode rod and the vessel wall form the plates of a capacitor. If the level of the dielectric located
between these two capacitor plates changes, the current which flows through the plates changes
proportionally to the level. A dielectric is by definition an insulating substance, which excludes many
liquids such as water. In order to receive a useful measuring result the measuring rod, which is
submerged to varying depths in the liquid, must be completely insulated.
After the calibration of the zero point/measuring range (0 %/00 %) the level can be read off from a
remote display unit. The level measuring range can be changed during operation.
At regular intervals the level electrode NRG 26-40 sends a data telegram to the level switch NRS 2-40
or level controller NRR 2-40. The data transfer is effected by means of a CAN bus according to DIN ISO
898 using the CANopen protocol.