GESTRA NRGT 26-2n User manual

Original Installation &
Operating Manual
EN
English
Level Transmitter
NRGT 26-2n
850879-00

2NRGT 26-2n - Installation & Operating Manual - 850879-00
Contents
Content of this Manual................................................................................................................................... 4
Scope of delivery/Product package............................................................................................................... 4
How to use this Manual.................................................................................................................................. 5
Illustrations and symbols used...................................................................................................................... 5
Hazard symbols in this Manual...................................................................................................................... 5
Types of warning ............................................................................................................................................ 6
Specialist terms / Abbreviations.................................................................................................................... 7
Usage for the intended purpose..................................................................................................................... 8
Improper use .................................................................................................................................................. 9
Basic safety information .............................................................................................................................. 10
Required personnel qualifications............................................................................................................... 11
Notes on product liability............................................................................................................................. 11
Check the current output regularly ............................................................................................................. 11
Function ........................................................................................................................................................ 12
Technical data .............................................................................................................................................. 14
Example name plate/identification of the NRGT 26-2n............................................................................... 17
Factory settings............................................................................................................................................ 18
Overall view of the NRGT 26-2n ................................................................................................................... 19
Dimensions of the NRGT 26-2n.................................................................................................................... 20
Preparing for installation ............................................................................................................................. 21
Installation.................................................................................................................................................... 22
Installing the NRGT 26-2n........................................................................................................................ 23
Sealing surface dimensions of the NRG 26-2n ......................................................................................... 23
Example .................................................................................................................................................. 23
Installing two level electrodes in a flange .................................................................................................. 24
Installation.................................................................................................................................................... 25
Installing two level electrodes in a flange by detaching a terminal box ..................................................... 25
Installing two level electrodes in a flange by detaching a terminal box ..................................................... 26
Installation examples with dimensions for the NRGT 26-2n ...................................................................... 27
Aligning the terminal box............................................................................................................................. 32
Functional elements of the NRGT 26-2n...................................................................................................... 33
Electrical connection.................................................................................................................................... 34
Notes on electrical connection ................................................................................................................. 34
Connecting the 24 V DC power supply ..................................................................................................... 34
Connecting the actual value output (4-20 mA).......................................................................................... 34
Pin assignment of the M12 connector for non pre-wired control cables ................................................... 34

3NRGT 26-2n - Installation & Operating Manual - 850879-00
Contents
Bringing into service .................................................................................................................................... 35
Changing the factory settings if necessary............................................................................................... 35
Calibration to the lower limit of the active measuring range “CAL.L” (0% calibration value) ...................... 37
Perform independent rapid calibration at a water level of > 25% of the active measuring range “CAL.P”...... 38
Calibration to the upper limit of the active measuring range “CAL.H” (100% calibration value)................. 38
Setting the filter constant “Filt”................................................................................................................ 38
Manually initiating a display test .............................................................................................................. 39
Checking the level display by raising or reducing the level ....................................................................... 39
Checking function by initiating a test function .......................................................................................... 39
Starting, operation and testing .................................................................................................................... 40
System malfunctions.................................................................................................................................... 43
Causes .................................................................................................................................................... 43
Indication of system malfunctions using error codes................................................................................ 44
Common application and usage errors..................................................................................................... 46
Checking installation and function ........................................................................................................... 48
Taking out of service.................................................................................................................................... 49
Cleaning the measuring electrode of the level transmitter ........................................................................ 50
Cleaning interval...................................................................................................................................... 50
Disposal ........................................................................................................................................................ 50
Returning decontaminated equipment........................................................................................................ 50
Declaration of Conformity; Standards and Directives................................................................................. 51

4NRGT 26-2n - Installation & Operating Manual - 850879-00
Content of this Manual
Product:
■ Level transmitter NRGT 26-2n
First edition:
BAN 850879-00/05-2022cm
© Copyright
All rights reserved. Any misuse, particularly reproduction and dissemination to third parties, is not permit-
ted. The General Terms & Conditions of GESTRA AG apply.
Scope of delivery/Product package
■ 1 x level transmitter NRGT 26-2n
■ 1 x sealing ring D 27 x 32, form D, DIN 7603-2.4068, bright annealed
■ 1 x Installation & Operating Manual
Required accessories for NRGT 26-2n when installing for the first time
■ 1 x cable jack, Phoenix Contact SACC-M12FS-5PL-SH

5NRGT 26-2n - Installation & Operating Manual - 850879-00
How to use this Manual
This Installation & Operating Manual describes the correct use of the NRGT 26-2n level transmitter. It
applies to persons who integrate this equipment in control systems, install, bring into service, operate,
maintain and dispose of this equipment. Anyone carrying out the above-mentioned activities must have
read this Installation & Operating Manual and understood its contents.
■ Read this Manual in full and follow all instructions.
■ Please also read the instructions for use of any accessories.
■ The Installation & Operating Manual is part of the product package. Keep it in an easily accessible
location.
Availability of this Installation & Operating Manual
■ Make sure this Installation & Operating Manual is always available to the operator.
■ If you pass on or sell the equipment to a third party, please also hand over the Installation & Operating
Manual.
Hazard symbols in this Manual
Danger zone / Dangerous situation
Illustrations and symbols used
1. Action to be taken
2.
■ Lists
◆ Bullet points in lists
A Keys to illustrations
Additional
information
Read the relevant
Installation & Operating Manual

6NRGT 26-2n - Installation & Operating Manual - 850879-00
Types of warning
DANGER
Warning of a dangerous situation that results in death or serious injury.
WARNING
Warning of a dangerous situation that may possibly result in death or serious injury.
CAUTION
Warning of a situation that may result in minor or moderate injury.
ATTENTION
Warning of a situation that results in damage to property or the environment.

7NRGT 26-2n - Installation & Operating Manual - 850879-00
Specialist terms / Abbreviations
Here, we explain some abbreviations, specialist terms, etc., which are used in this Manual.
NRGT .. / NRR.. / NRS.. / URS .. / URB .. / SRL .. / etc.
Equipment and type designations of GESTRA AG.
SELV
Safety Extra Low Voltage
Operating point (of the system)
The operating point describes the operating parameters within which a system or boiler is operated in its
nominal range. In a pressurised steam boiler, for example, these parameters would be output, capacity,
pressure and temperature.
The design data may be a lot more stringent, however.
A boiler that is operated at 10 bar and 180°C may be designed for a pressure of 60 bar and a tempera-
ture of 275°C, for example, which is not necessarily its operating point.

8NRGT 26-2n - Installation & Operating Manual - 850879-00
Usage for the intended purpose
Use as a water level controller
The NRGT 26-2n level transmitter can be used to continually measure the water level in steam boiler and
hot-water installations, or in condensate and feedwater tanks. The calibrated measuring range from 0%
to 100% makes up the linear profile of the 4-20 mA current output.
Influence of the fluid to be monitored
■ The NRGT 26-2n level transmitter can be used in fluids with different conductivity and in insulating
media. However, a conductivity of less than 100 μS/cm has a major influence on the measured capac-
itance, which is why recalibration of the measuring range (see page 37) at the operating point* and
after a cold start is extremely important.
* Operating point of the system, see page 7.
■ To achieve the best possible reproducibility and maintain high-quality measurements (see “Technical
data” on page 14), the sensor must be installed in a protective tube (see “Installation examples with
dimensions for the NRGT 26-2n” on page 27 ff).
■ The dielectric constant of the measured medium may require an adjustment to the measurement
frequency if it deviates significantly from that of the usual water (Er = 80). Please contact GESTRA
Service.

9NRGT 26-2n - Installation & Operating Manual - 850879-00
Usage for the intended purpose
Systems without SIL rating
In systems without a SIL rating, any controller, display unit or diagnostic tester with an input for a stand-
ard 4-20 mA signal can be connected.
To ensure proper use in all applications, please also read the Installation & Operating Manuals
for the system components used.
■ You can find the latest Installation & Operating Manuals for other system components on our
website:
http://www.gestra.com
Improper use
There is a danger of death due to explosion if the equipment is used in potentially explo-
sive atmospheres.
Do not use the equipment in potentially explosive atmospheres.
Do not bring any equipment into service that does not have its own specific name plate.
The name plate indicates the technical features of the equipment.

10 NRGT 26-2n - Installation & Operating Manual - 850879-00
Danger to life from scalding if the level electrode is removed under pressure. Steam or
hot water can spurt forcefully out of the equipment.
■ Only remove the level electrode at 0 bar boiler pressure.
Risk of severe burns if work is performed on a level electrode that has not been allowed
to cool. The level electrode becomes very hot during operation.
■ Always allow the level electrode to cool.
■ Perform all installation and maintenance work only on a level electrode that has been
allowed to cool.
There is a risk of electric shock during work on electrical systems.
■ Always switch off the voltage to the system before performing connection work.
■ Check that the system is not carrying live voltage before commencing work.
Danger to life from a faulty NRGT 26-2n level electrode due to the sudden escape of hot
steam or hot water.
Shocks and impacts during transport or installation can result in damage to or leaks in the level
electrode, causing pressurised hot steam or hot water to escape through the pressure relief
hole.
■ To prevent damage during transport and installation, do not expose the electrode
rod to major shocks or impacts.
■ Before and after installation, check that the level electrode is completely undamaged.
■ Check that the level electrode is not leaking when bringing into service.
Attempts to repair the equipment will lead to non-availability of the system.
■ The NRGT 26-2n level electrode may only be repaired by the manufacturer, GESTRA AG.
■ Only replace faulty equipment with identical equipment from GESTRA AG.
Basic safety information

11NRGT 26-2n - Installation & Operating Manual - 850879-00
Required personnel qualifications
Activity Personnel
Integration in control system Specialist staff Plant designer
Installation/electrical
connection/bringing into service Specialist staff
The equipment may only be installed, wired
and brought into service by qualified and
competent staff.
Operation Boiler service technician Staff trained by the plant operator.
Maintenance work Specialist staff
Maintenance and conversions may only be
performed by authorised staff who have
undergone specific training.
Refits Specialist staff Persons trained by the plant operator to work
with pressure and temperature.
Fig. 1
Notes on product liability
The manufacturer cannot accept any liability for damages resulting from improper use of the equipment.
Check the current output regularly
Check level electrode function at least once a year by bringing the system to the minimum and/or maxi-
mum water level (T1 = 1 year).
The test function is initiated on site using the integrated rotary knob on the terminal box, see page 42.

12 NRGT 26-2n - Installation & Operating Manual - 850879-00
Function
The NRGT 26-2n level transmitter uses the capacitance measurement principle and converts level data
into a level-dependent 4-20mA current signal. The 0-100% measuring range can be scaled based on the
effective length of the electrode rod.
Automatic self-test
An automatic self-test periodically monitors the safety and function of the level transmitter and measured
value acquisition.
Faults in the electrical connection or electronic measuring equipment trigger a fault indication on the
display, and the current output is set to 0mA.
Transmitter function
The transmitter function is the ability of the electrode to provide a scalable measuring range on the
4-20 mA current output interface and to make this available to one or more recipients for analysis.
These transmitters do not have any controlling or limiting functions.
The level transmitter is installed on the inside of steam boilers, tanks or feed lines of hot-water installa-
tions. A protective tube (see “Installation examples” on page 27) provided on site keeps the transmitter
functioning reliably.
A capacitance NRGT 26-2n level transmitter and a conductivity NRG 1x-60 or NRG1x-61 level electrode
can be installed in the same protective tube or level pot.
Operation in external level pots
If a level transmitter is installed outside the boiler in a level pot that can be shut off, the connecting pipes
must be flushed regularly.
If the steam pipe is ≥ 40 mm and the water pipe is ≥ 100 mm, installation is regarded as internal. In this
case, upstream monitoring of flushing processes is not required.
Display and signals, see pages 40/43 *
The NRGT 26-2n level transmitter features a green 4-digit, 7-segment display for showing readings,
status information and error codes. A red and green LED indicate the operating status.

13NRGT 26-2n - Installation & Operating Manual - 850879-00
Function
Behaviour when switched on *
The display alternately shows the software version, the type and then the scaled level reading.
Behaviour in normal operation (no errors) *
The display shows the scaled level reading (3 digits + 1 decimal place), e.g. 050.3, and converts the level
data into a level-dependent current signal from 4-20 mA.
The scale of the 0-100% measuring range is factory-set at a maximum for the electrode
length used. This way, meaningful level readings can be obtained immediately after instal-
lation.
Adjusting the measuring range when bringing into service (CAL.L, CAL.P or CAL.H)
When bringing into service, however, the measuring range should be adapted in line with your sight glass.
Do this using the parameters CAL.L, CAL.P or CAL.H, see pages 37 - 38. This is the only way to gain all
the benefits of high-resolution readings in the sight glass range.
Behaviour in the event of malfunctions *
The error state or malfunction is permanently shown on the display by an error code, e.g. E.005. For more
on error codes, see page 44.
Every time there is a fault, 0 mA is output via the current output.
Faults are displayed based on their priority. Indications with higher priority are shown conti-
nuously before those with low priority. If several indications need attention, the display does
not alternate between them.
Electrode faults cannot be acknowledged.
When the fault is corrected, the message disappears from the display, and the NRGT 26-2n
level transmitter returns to normal operation.
* The tables on pages 41 - 42 clearly show the relationship between the equipment status,
the display and the status LEDS.
Setting parameters and changing factory settings.
If necessary, you can adapt the electrode parameters to suit conditions at the plant. You can set parame-
ters and change factory settings using a rotary knob on the terminal box, see page 36 ff.

14 NRGT 26-2n - Installation & Operating Manual - 850879-00
Technical data
Model and mechanical connection
■ NRGT 26-2n Thread G¾ A, EN ISO 228-1, see Fig. 5
Nominal pressure rating, admissible service pressure and temperature
■ NRGT 26-2n PN 40 32 bar (g) at 238 °C
Materials
■ Terminal box 3.2581 G AlSi12, powder-coated
■ Cover tube 1.4301 X5 CrNi 18-10
■ Electrode rod insulation PTFE
■ Screw-in body 1.4571, X6CrNiMoTi17-12-2
Max. electrode length at 238°C, all measurements in mm
■ NRGT 26-2n
Max. electrode length: 373 477 583 688 794 899 1004
Measuring range: 300 400 500 600 700 800 900
Max. electrode length: 1110 1214 1319 1423 1528 1636 2156
Measuring range: 1000 1100 1200 1300 1400 1500 2000
Do not shorten the electrode rod.

15NRGT 26-2n - Installation & Operating Manual - 850879-00
Technical data
Measurement quality
The information below applies to a compensated fluid conductivity range from 100–10000µS/cm based
on 25 °C.
■ Reading error: +/- 1% from the set measuring range at the operating point
■ Resolution of reading on display: 0.1%
■ Resolution for internal processing: 15 bits with sign (16 bits)
■ Resolution of 4-20 mA output: 15 bits equivalent to 0.49 μA/digit
■ Sensitivity (minimum conductivity)
◆ Water ≥ 0.5 μS/cm (“Influence of the fluid to be monitored”)
Supply voltage
■ 24 V DC +/-20%
Power consumption
■ Max. 7 W
Current input
■ Max. 0.3 A
Internal fuse
■ T2A (slow blow)
Safety cutout at excessive ambient temperature
■ The cutout at excessive ambient temperature takes place at Tamb. = 75 °C
Analogue output
■ 1 x actual value output 4-20 mA, proportional to level, galvanically isolated
■ Maximum output load 500 Ω
■ M12 connector, 5-pole, A-coded
Indicators and controls
■ 1 x green 4-digit, 7-segment display for showing status information
■ 1 x red LED for indicating an error state
■ 1 x green LED for indicating an OK state
■ 1 x rotary knob IP65 with button for menu navigation and test function
Protection class
■ III Safety Extra Low Voltage (SELV)
IP rating to EN 60529
■ IP 65

16 NRGT 26-2n - Installation & Operating Manual - 850879-00
Technical data
Admissible ambient conditions
■ Service temperature: 0 °C – 70 °C
■ Storage temperature: - 40 °C – 80 °C
■ Transport temperature: - 40 °C – 80 °C
■ Air humidity: 10% – 95% non-condensing
Weight (dependent on length of electrode)
■ NRGT 26-2n approx. 1.8 kg (with 300 mm measuring range)
Admissible installation positions
■ Vertical
■ Oblique to a maximum inclination of 45°. In this case, the length of the electrode rod is limited
to 688 mm maximum.

17NRGT 26-2n - Installation & Operating Manual - 850879-00
Example name plate/identification of the NRGT 26-2n
The date of production is stamped on the screw-in body of the level transmitter.
Safety
note
Equipment designation
Nominal pressure rating, connection
thread, material of screw-in body
Equipment function
Admissible service pressure,
admissible temperature
Current approval,
conformity mark
Manufacturer
Serial number
IP rating
Supply voltage
Protection class
Disposal information
Fig. 2
Measuring range
Actual value output
Admissible ambient
temperature
Power consumption

18 NRGT 26-2n - Installation & Operating Manual - 850879-00
Factory settings
The NRGT 26-2n level transmitter has the following factory settings:
Menu display Parameter values Unit
CAL.L variable 0% Raw value (hex)
approx. 50 mV
CAL.P variable 25% Raw value (hex)
CAL.H variable 100% Raw value (hex)
approx. 2.0 V
FiLt 0005 seconds
Fig. 3

19NRGT 26-2n - Installation & Operating Manual - 850879-00
OK
!
+
-
Overall view of the NRGT 26-2n
Fig. 4
A Terminal box
B Operating panel with 4-digit LED display/
malfunction and status LEDs and rotary knob, see
page 40
C Cover screws M4 x 16 mm
D M12 connector, 5-pole, A-coded
F Seal seat for sealing ring
I Electrode
G Sealing ring D 27 x 32, form D, DIN 7603-2.4068,
bright annealed
E Cover tube (simplified view)
H Electrode thread
J Electrode rod insulation, PTFE

20 NRGT 26-2n - Installation & Operating Manual - 850879-00
Dimensions of the NRGT 26-2n
Fig. 5 All lengths and diameters
in mm
OK
!
+
-
140
G ¾
Size 41mm A.F.
0
Nm
50 70 90
110
120 100 80 60
41
175
w = 70
26 237
1 338
20
Thermal insulation
provided at the site
Ø15
1 2
Max.
electrode length
at 238 °C
Measuring
range
373 300
477 400
583 500
688 600
794 700
899 800
1004 900
1110 1000
1214 1100
1319 1200
1423 1300
1528 1400
1636 1500
2156 2000