NES
page 4
NES K05/0922
4. Regulation Use
The KOBOLD limit switches of model NES are used in connection with the
electrode relay, model: NE, for level monitoring and pump control of conductive
liquids. The design without any moving parts allows service with critical media
with, for example, solid content, negligible density or high viscosity.
The minimum medium conductivity should be 20 µS/cm.
Any use of the device which exceeds the manufacturer’s specifications, may
invalidate its warranty. Therefore, any resulting damage is not the responsibility of
the manufacturer. The user assumes all risk for such usage.
5. Operating Principle
The instruments operate on the conductive principle. A low a.c. voltage is applied
between the conductive wall of the tank or the ground electrode (longest
electrode) and one respectively several switching point electrode. If the
conductive medium touches the electrodes, a negligible alternating current flows
across the electrodes and the conductive medium to the electrode relay. The
relay amplifies the alternating current and operates one bi-stable interval relay
with lock which is therefore suitable for an interval switching e.g. of a pump
control (min./max. control).
Unlike to the NE-104 with only one limit value indication, one connection for a
ground electrode and one min. and max. electrode, the relay NE-304 can observe
two signals. The NE-304 offers connections for one ground electrode and two
level limits at a time.
The outputs of NE-304 can both be operated as a min./max. control or separately
as a limit switch (alarm) and a min./max. control.
