12. Declaration of Compliance ...................................................9
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: info.de@kobold.com
Internet: www.kobold.com
Page 2 NTB K02/1009
NTB
2. Note
Please read these operating instructions before unpacking and putting the unit
into operation. Follow the instructions precisely as described herein.
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.
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.
Any use of the Deep-well probe, model: NTB, which exceeds the manufacturer’s
specification 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 immersion probe comprises a measuring cell, two-wire transmitter and
special cable with capillary tube. The housing is made out of stainless steel with a
pressure-sensitive diaphragm that is protected with a plastic cap. The level signal
is determined by the pressure difference between the water column over the
probe and atmospheric pressure which is transferred to the probe through the
capillary tube. This differential pressure is converted to a 4 to 20 mA analogue
signal by the piezo-resistive cell and the fitted electronics.
NTB K02/1009 Page 3
NTB
OVP
Red(+)
capillary
Connection box
Shield
6. Mechanical Connection
The immersion probe is immersed up to the deepest point into the well or the
basin. This is because only the water column above the sensor is measured.
The probe may not fall onto the water surface, but must be immersed
carefully, since otherwise the membrane will be destroyed.
Fasten the cable in such a way, so that the probe hangs freely and the
capillary and supply pipe are not squeezed together. To anchor it properly, wind
the tube three to four times around a pipe having a diameter from 50 to 100 mm
and fix the cable-ends with a cable-strap. The cable end should be prepared
according to the following diagram.
Moisture must not be allowed to enter the capillary.
Ø 50-100
Black(-)
GND
An over-voltage protection (NTB-OVP) should be used with the outdoorinstallation. The grounding of the over-voltage protection must be connected to
the protective grounding via the shortest path available. Please observe the
relevant regulations and safety standards (VDI/VDE).
If the conductor length in the open field is larger than 15 m (outdoors) between
transducer and evaluation electronics, an additional over-voltage protection
needs to be employed.
Page 4 NTB K02/1009
NTB
Power
supply
switch
Limit
Protection pipe
4...20 mA
4...20 mA
OVP OVP
Screen
Input Output
To protect sensor against pressure-surges, the immersion probe can be placed
inside a pipe.
7. Electrical Connection
The sensor and the over-voltage protector should be connected according to the
following diagram.
The conductor, on which over-voltage may
develop, must be connected to the input
terminals of over-voltage protector. The
sensor and evaluation-unit must be
connected to the output terminals.
NTB K02/1009 Page 5
NTB
8. Maintenance
In case the medium to be measured is not contaminated, NTB units are
maintenance-free. If the dirt forms on membrane and needs to be cleaned, make
sure you do not use any hard cleaning agents. If damaged, repair of membrane is
possible only by the manufacturer.
Cup: ABS
Overload capacity: 3 x measuring range
Output signal: 4 to 20 mA, 2-wire
Accuracy: ±0.5% of full scale
Effects of ambient
temperature: ±0.1%/10 K
Offset error: ±0.1 mA
Auxiliary power: 9...30 V
Load:
DC
Protection: IP 68
Operating temperature: -10 °C...+60 °C
Dimensions of probe: Ø 22 x 145 mm
Cross-section of cable: 0.34 mm
Cable length: up to 300 m (see order details)
Overvoltage protection
NTB-OVP12: field mounting
NTB-OVP32: rail DIN 46277-3
Maximum voltage (peak value)
Slow: 90 V pp
Fast: 30 V pp
Series resistor: 13 Ω ±10%
Pulse power: 600 W / 1 ms
Protection: IP 54 (NTB-OVP 12)
IP 20 (NTB-OVP 32)