Kobold NE-104 User manual
Operating Instructions
for
Conductive Level
Limit Switch
Model: NES, NE-104/-304
NES
page 2 NES K05/0922
1. Contents
1.Contents ........................................................................................................ 2
2.Note .............................................................................................................. 3
3.Instrument Inspection .................................................................................... 3
4.Regulation Use ............................................................................................. 4
5.Operating Principle ........................................................................................ 4
6.Mechanical Connection ................................................................................. 5
7.Electrical Connection .................................................................................... 6
7.1Conductive Level Switch (Electrodes with screw in thread and
housing) ............................................................................................... 6
7.2NE-104 Electrode Relay ...................................................................... 7
7.3NE-304 Electrode Relay ...................................................................... 8
7.4Application examples with Electrode Relay NE-104 .......................... 10
8.Commissioning............................................................................................ 12
9.Locating and Remedying Faults .................................................................. 12
10.Maintenance ............................................................................................... 13
11.Technical Data ............................................................................................ 14
12.Order Codes ............................................................................................... 15
13.Dimensions ................................................................................................. 16
13.1Electrodes with Housing .................................................................... 16
13.2Electrode Relay ................................................................................. 17
14.Disposal ...................................................................................................... 18
15.EU Declaration of Conformance ................................................................. 19
Manufactured and sold by:
Kobold Messring GmbH
Nordring 22-24
D-65719 Hofheim
Tel.: +49(0)6192-2990
Fax: +49(0)6192-23398
E-Mail: [email protected]
Internet: www.kobold.com
NES
NES K05/0922 page 3
2. Note
Please read these operating instructions before unpacking and putting the unit
into operation. Follow the instructions precisely as described herein.
The instruction manuals on our website www.kobold.com are always for currently
manufactured version of our products. Due to technical changes, the instruction
manuals available online may not always correspond to the product version you
have purchased. If you need an instruction manual that corresponds to the
purchased product version, you can request it from us free of charge by email
([email protected]) in PDF format, specifying the relevant invoice number and
serial number. If you wish, the operating instructions can also be sent to you by
post in paper form against an applicable postage fee.
The devices are only to be used, maintained and serviced by persons familiar
with these operating instructions and in accordance with local regulations
applying to Health & Safety and prevention of accidents.
When used in machines, the measuring unit should be used only when the
machines fulfil the EC-machine guidelines.
3. Instrument Inspection
Instruments are inspected before shipping and sent out in perfect condition.
Should damage to a device be visible, we recommend a thorough inspection of
the delivery packaging. In case of damage, please inform your parcel service /
forwarding agent immediately, since they are responsible for damages during
transit.
Scope of delivery:
The standard delivery includes:
Conductive Level Limit Switch model: NES
respectively conductive electrode relay model: NE
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.
NES
NES K05/0922 page 5
6. Mechanical Connection
The electrodes can for example be screwed into the tank cover and sealed via a
pipe thread. The electrode length corresponds to the desired switching points and
may be shortened as necessary. The electrode tip must be free of insulating
materials. The electrodes must be installed so that the electrode rods or the
pendant electrodes are not short-circuited neither by the side of the tank, nor by
each other. Please ensure that the rods do not bend. The reference or ground
electrode must be at least as long as the longest switching electrode. If the side
of the tank is adequately conductive and is not coated with insulating material, it
can be used as a ground electrode. The clearance between the switching
electrode and the side of the tank should be as small as possible, so that the
conductivity of the measuring distance does not drop below 20S/cm.
Generally, please note:
The level probes are generally intended for vertical installation.
Short level electrodes, up to approx. 300 mm in length, can be installed in
other positions.
Long level electrodes must be supported if subjected to high lateral loads.
If used in liquids which form a conductive coating on the electrode insulation,
push the spacer away from the end of the electrode insulation by at least
150 mm. This means that you will obtain a high transition resistance with an
uncovered electrode.
When shortening an electrode, please ensure that electrode cladding is not
damaged at other places during the trimming operation. Remove the rod
cladding at the tip of the probe over a length of 3 - 5 mm.
The screw in thread should be sealed with appropriate sealant.
Ensure that the insulation of the rods is not damaged during
insertion of the rods into the flange or the screw-fitting.
NES
page 6 NES K05/0922
7. Electrical Connection
7.1 Conductive Level Switch (Electrodes with screw in thread
and housing)
The Conductive Level Switch is supplied with built-in terminal block for
electrical connection.
Numbering: shortest electrode 1; second-shortest electrode 2, etc.
The Conductive Level Switch can only be used in conjunction with a suitable
electrode relay (e.g. NE-104 or NE-304).
Ensure that the cable gland and the housing cover of the limit switch
are strongly tightened after connection.
Maximum cable length: 300 m, minimum cross-section 0,5 mm².
Starting at a cable length of approx. 15 m and for EMC critical
installation environment, a screened and low capacity cable must be
used which is connected to an adequate shiled ground
NES
NES K05/0922 page 7
7.2 NE-104 Electrode Relay
The NE-104 electrode relay is the standard relay for all
conductive limit electrodes. It is supplied with a
quiescent current relay, i.e., the relay picks up (contact
6-7 closes) when auxiliary power is applied. If the
electrodes are wetted or the power fails, the relay
disengages (contact 7-8 closes). The signal lamp (red
LED) is energised when the relay picks up.
Electrode connection
Usage as Min./Max. switch (2 electrodes)
Connect the ground or reference electrode to terminal 14.
Connect the switching electrode to terminal 15.
Level Relay LED
Below the switching electrode relay picks up, contact 6-7 closed on
Reaches or above the switching electrode relay drops out, contact 7-8 closed out
Usage as interval control (3 electrodes)
Connect the ground or reference electrode to terminal 14.
Connect the Max-switching electrode to terminal 15 and the Min-switching
electrode to terminal 16.
Contact 6-7 is closed when the tank is empty. When the liquid reaches the
Max. electrode, the relay changes over and contact 7-8 closes. The relay
remains changed over until the level falls below the Min. electrode. The
interval then repeats itself.
The changeover contact may be used for evacuating or filling - as shown in the
circuit examples.
Terminating the mains voltage
The mains voltage is terminated at terminals 1 and 2, and the protective
ground conductor at terminal 3 (PE).
Note: Terminal 14 (ground) is internally linked to terminal 3 (PE).
NES
page 8 NES K05/0922
7.3 NE-304 Electrode Relay
The NE-304 electrode relay is a double relay with two
separated electrode circuits and one reference electrode. It
is supplied with a quiescent current relay, i.e., the relay
picks up (contact 3-4 and 6-7 close) when auxiliary power is
applied. If the electrodes are wetted or the power fails, the
relay disengages (contact 4-5 and 7-8 close). The signal
lamps (red LED`s) are energised when the relay picks up.
Electrode connection
Usage as Min./Max. switch (3 electrodes)
Connect the ground or reference electrode to terminal 10.
Connect Min.-switching electrode to terminal 12 and the Max.-switching
electrode to terminal 15.
Level Relay LED
Min-
electrode
Reaches or above the switching electrode relay drops out, contact 4-5 closed out
Below the switching electrode relay picks up, contact 3-4 closed on
Max.-
electrode
Reaches or above the switching electrode relay drops out, contact 7-8 closed out
Below the switching electrode relay picks up, contact 6-7 closed on
Usage as two interval controls (5 electrodes)
Connect the ground or reference electrode (longest rod) to terminal 10.
Pump 1: Connect the Max.-switching electrode to terminal 12 and the Min.-
switching electrode to terminal 13. Contact 3-4 is closed when the tank is
empty (LED 1-on). When the liquid reaches the Max. electrode, the relay
changes over and contact 4-5 closes (LED 1-out). The relay remains changed
over until the level falls below the Min. electrode. The interval then repeats
itself.
Pump 2: Connect the Max.-switching electrode to terminal 15 and the Min.-
switching electrode to terminal 16. Contact 6-7 is closed when the tank is
empty (LED 2-on). When the liquid reaches the Max. electrode, the relay
changes over and contact 7-8 closes (LED 2-out). The relay remains changed
over until the level falls below the Min. electrode. The interval then repeats
itself.
The changeover contact may be used for evacuating or filling—as shown in
the circuit examples.
NES
NES K05/0922 page 9
Usage as one interval control and one switch point (4 electrodes)
Connect the ground or reference electrode (longest rod) to terminal 10.
Pump 1: Connect the Max.-switching electrode to terminal 12 and the Min.-
switching electrode to terminal 13.
Connect the switch point electrode to terminal 15.
Terminating the mains voltage
The mains voltage is terminated at terminals 1 and 2, and the protective
ground conductor at terminal 9 (PE).
Note: Terminal 10 (ground) is internally linked to terminal 9 (PE).
NES
page 10 NES K05/0922
7.4 Application examples with Electrode Relay NE-104
P
M
Power supply
Power
supply
Draining the tank
P
M
Power supply
Power
supply
Filling the tank
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