Kobold NRM User manual

Operating Instructions
for
Non-Contact Radar Level Transmitter
Model: NRM

NRM
page 2 NRM K06/0422
We don’t accept warranty and liability claims neither upon this publication nor in
case of improper treatment of the described products.
The document may contain technical inaccuracies and typographical errors. The
content will be revised on a regular basis. These changes will be implemented in
later versions. The described products can be improved and changed at any time
without prior notice.
© Copyright
All rights reserved.
1. Contents
1.Contents ........................................................................................................ 2
2.Note .............................................................................................................. 4
3.Instrument Inspection .................................................................................... 4
4.Regulation Use ............................................................................................. 4
5.Operating Principle ........................................................................................ 5
6.Installation ..................................................................................................... 6
6.1Mounting .............................................................................................. 6
7.Wiring ............................................................................................................ 9
7.1Wiring of the devices ......................................................................... 10
7.2Determine the appropriate power supply voltage ............................... 11
7.3Loop current checking with hand instrument ...................................... 12
8.Programming .............................................................................................. 12
8.1The NRM-300P display unit ............................................................... 13
8.2Programming with the NRM-300P display module ............................ 16
8.3Programmable features description ................................................... 18
9.Error Codes ................................................................................................. 28
10.NRM Parameter table ................................................................................. 29
11.Menu map ................................................................................................... 30
12.Explosion protection, Ex-marking, Ex limit data .......................................... 32
13.Conditions of safe operation ....................................................................... 33
14.Maintenance ............................................................................................... 33
15.Technical Information .................................................................................. 34
16.Order Codes ............................................................................................... 35
17.Dimensions ................................................................................................. 37
18.EU Declaration of Conformance ................................................................. 40
19.EU Declaration of Conformance (ATEX) ..................................................... 41
20.ATEX certificate .......................................................................................... 43
21.IECEx certificate .......................................................................................... 50

NRM
NRM K06/0422 page 3
Manufactured and sold by:
Kobold Messring GmbH
Nordring 22-24
D-65719 Hofheim
Tel.: [phone]
Fax: [phone]
E-Mail: [email protected]
Internet: www.kobold.com
Edition: August 2017 (Revision 3)

NRM
page 4 NRM K06/0422
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:
 Non-Contact Radar Level Transmitter model: NRM
4. Regulation Use
Any use of the Non-Contact Radar Level Transmitter, model: NRM, 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.

NRM
NRM K06/0422 page 5
5. Operating Principle
The reflection of the emitted microwave impulses is considerably depending on the
relative dielectric constant of the measured medium. The essential condition of
microwave level measurement is that the relative dielectric constant (εr) of the
medium should be more than 1.9.
The operation of the non-contact microwave level transmitters is based on the
measurement of the time of flight of the reflected signals, so-called Time Domain
Reflectometry (TDR) method.
The propagation speed of microwave impulses is practically the same in air, gases
and in vacuum, independently from the process temperature and pressure, so the
measured distance is not affected by the physical parameters of medium to be
measured.
The NRM level transmitter is a Pulse Burst Radar operating at 25 GHz (K-band)
microwave frequency.
The 25 GHz models’ most noticeable advantage over the lower frequency
(5-12 GHz) radars are the smaller antenna size, the better focusing, lower
dead-band and smaller transmission angle.
The level transmitter induces few nanosecond length microwave impulses in the
antenna and a part of the energy of the emitted signals reflects back from the
measurement surface depending on the measured media. The time of flight of the
reflected signal is measured and processed by the electronics, and then this is
converted to distance, level or volume proportional data.

NRM
page 6 NRM K06/0422
6. Installation
6.1 Mounting
When choosing the installation place please ensure proper space for later
calibrations, verification or maintenance service.
PLACEMENT
The ideal position for the NRM is on the
r = (0.3 … 0.5) R (in case of cylindrical tank).
It is highly recommended to consider the beam
cone. The distance between the sensor and the
tank wall should be at least 200 mm.
If the unit is installed into dome top or spherical
tank, unwanted multiple reflections may appear,
which can cancel each other and the measuring
signal out, this way it can interfere the
measurement.
r
R
MOVING LIQUID SURFACE
Waving, vortex or strong vibration effects can
have negative influence on the measurement
accuracy and the maximal measuring range. To
avoid these effects, the mounting placement
should be as far as possible from the sources of
these disturbing effects. According to
measurement experiences the maximal
measuring distance may decrease by 50-70%
when the liquid surface is vortexing. For this
reason the device should be mounted as far as
possible from the filling stream or the tank outlet.
FOAMING
Filling, stirring or any other
processes in the tank can generate
dense foams on the liquid surface,
which may considerably damp the
reflected signals.
According to measurement
experiences, in these cases the
maximal measuring distance
decreases at least approximately
b
y
50%.
FUMES, VAPOURS
If the measured medium or its
foam can reach the antenna
or the measured medium is
highly fuming, these cases
build-ups can form on the
sensor, which may result
unreliable level
measurement.

NRM
NRM K06/0422 page 7
SENSOR ALIGNMENT
The antenna face should be parallel to
the medium surface within  2-3°.
TEMPERATURE
To avoid
overheating the
instrument should
be protected
against direct
sunshine.
Á
rnyékoló tető
OBSTACLES
Prior to the installation make sure that
no objects (cooling pipes, bracing
elements, thermometers, etc.) cross the
microwave signals. Especially in case
of extraordinary large silos bracing
elements and other structural obstacles
may cause false reflections which can
be damped in most cases: a small bent
metal deflector plate mounted above
the obstacle can disperse the
microwave signals and eliminates the
false reflections which disturb the
reliable measurement.
If there is no possible mechanical
solution to avoid these kinds of false
reflections, the programming of the
instrument allows blocking out the
obstacles. (see: 8.3.4.5)
POLARIZATION
PLANE
The emitted radar impulses
of NRM are electromagnetic
waves. The orientation of
the polarization plane is the
same as for the electric
wave component of the
electro-magnetic wave. The
rotation of the polarization
plane compared to the tank
position could be useful (for
example to avoid disturbing
reflections) in certain
applications. To rotate the
polarization plane loosen
the M6 hex socket set screw
above the process
connection and rotate the
instrument. Then tighten the
unit b
y
the screw.
M6/Sw.3

NRM
page 8 NRM K06/0422
EMPTY TANK
Especially in case of standing tanks
with hemispherical bottom and in case
of tanks which have any equipment
inside at the bottom (e.g. heating
element, stirrer) wrong level
measurement may happen when the
tank is totally emptied. The reason for
this measurement error is that the tank
bottom or the objects at the bottom
disperse or reflect the emitted
microwave signals. Furthermore the
lower signal-level dispersed radar
impulses may interfere with itself inside
the tank.
In order to perform reliable level
measurement there should be at least
100 mm liquid level above the
disturbing objects at the bottom or
above the hemispherical tank bottom.
SOCKET, NOZZLE
The process connection should be
implemented that the antenna end should
protrude at least 10 mm out of the socket.
>10mm >10mm

NRM
NRM K06/0422 page 9
7. Wiring
The instrument operates from 20 … 36 V galvanic
isolated and not grounded DC power supply in two-
wire system. (For Ex version: 20 … 30 V DC!)
The voltage value measured on the terminal of the
instrument should be minimum 20 V (in case of 4 mA)!
In case of using HART interface – to achieve proper
communication between the transmitter’s interface
and the power-supply – a minimal 250 Ohm resistance
should be maintained within the network. The
instrument should be wired with shielded cable led
through the cable gland. The wiring of the cables can
be done after removing the cover of the instrument
and the NRM-300P display unit.
IMPORTANT: The grounding screw on the housing of
the transmitter should be connected to the
equipotential network. Resistance of the EP network
should be R  2 Ohm measured from the neutral point.
Shielding of the cable should be grounded at the
control room side to the EP network. To avoid
disturbing noises, keep away of closeness to high-
voltage cables. Especially the inductive couplings of
AC harmonics can be critical (which are present at
frequency converter control) because even cable
shielding does not supply effective protection against
these cases.
234561
1/2” NPT
Display unit
connector
Loop current
measuring connector
4...20 mA
(HART)
loop current
and supply
GND
1/2” NPT
M20x1,5
M20x1,5
3425
U-+
The instrument may be damaged by electrostatic discharge (ESD) via its
terminal, thus apply the precautions commonly used to avoid electrostatic
discharge e.g. by touching a properly grounded point before removing the
cover of the enclosure.
A possible electrostatic discharge can cause damage for the instrument. Do
not touch the internal terminals!

NRM
page 10 NRM K06/0422
WATER / VAPOUR
To achieve suitable ingress protection Kobold
recommends using the suggested cable outer
diameter and fasten properly the cable gland.
Kobold also recommends leading the connecting
cables downwards to lead aside the rain water and the
condensed water. This is needed in case of outside
installations and some special applications where
there is very high humidity or the possibility of water
condensation is quite high (for example in cleaning,
purification processes, in cooled and / or heated
tanks).
7.1 Wiring of the devices
Using HART communication Using Ex approved instrument
In non-Ex environment in hazardous environment
In case of integrated version:
Prior to wiring ensure that the power supply is turned off at the source.
(For wiring the unit 6 x 0.5 mm2 cross section or greater cable is recommended).
The necessary programming can be made after energizing the unit.
Colour codes of the wires:
Green – (+) Positive point of current loop measurement
Yellow – (-) Negative point of current loop measurement
White – I (-) Negative point of current loop, power supply and HART
Brown – I (+) Positive point of current loop, power supply and HART
Green/Yellow – GND Grounding and shielding point