5
Explanatory Notes
System description
The level electrode NRG 26-2 works according to the capacitance measurement principle. The
NRG 26-2 is used for signalling different levels in electrically conductive and non-conductive liquids:
n
Levels maintained within the control band defined by two preset limits
The preamplifier NRV 2-29 is integrated in the terminal box of the level electrode.
Function
Design
The principle of capacitance measurement is applied to determine the level. The electrode rod and
the vessel wall form a capacitor. If the level of the dielectric located between the two capacitor plates
changes, the current which flows through the plates changes proportionally to the level.
A dielectric is defined as 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.
NRG 2621
Screwed design ¾", DIN ISO 228-,
Fig. 2
Scope of supply
NRG 2621
Level electrode NRG 26-2 with joint ring D 27 x 32 DIN 7603, .430 bright annealed
Installation manual
