GESTRA NRG 26-61 User manual

Original Installation &
Operating Manual
EN
English
Level Electrode
NRG 26-61
819874-00

2NRG 26-61 - Installation & Operating Manual - 819874-00
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
Applicable directives and standards...........................................................................................................9
Admissible system components, dependent on the required safety level..................................................10
Improper use ................................................................................................................................................ 11
Basic safety notes ........................................................................................................................................ 12
Required personnel qualifications............................................................................................................... 13
Notes on product liability............................................................................................................................. 13
Functional safety, safety integrity level (SIL) .............................................................................................. 14
Check the safety function regularly..........................................................................................................14
Reliability data to EN 61508 ......................................................................................................................... 15
Function ........................................................................................................................................................ 16
Technical data .............................................................................................................................................. 19
Name plate/Identification ............................................................................................................................ 21
Factory settings............................................................................................................................................ 22
Overall view of the NRG 26-61 ..................................................................................................................... 23
Dimensions of the NRG 26-61 ...................................................................................................................... 24
Preparing for installation ............................................................................................................................. 25
Installation.................................................................................................................................................... 26
Sealing surface dimensions for NRG 26-61.............................................................................................. 27
Example ..................................................................................................................................................27
Installing two level electrodes in a flange................................................................................................. 28
Installation examples with dimensions....................................................................................................... 29
Aligning the terminal box............................................................................................................................. 34
Functional elements..................................................................................................................................... 35
Connecting the CAN bus system.................................................................................................................. 36
Bus line, cable length and cross-section .................................................................................................. 36
Example ..................................................................................................................................................36
Important notes on connecting the CAN bus system................................................................................. 37
Pin assignment of the CAN bus connector and coupling for non pre-wired
control cables..........................................................................................................................................37

3NRG 26-61 - Installation & Operating Manual - 819874-00
Contents
Bringing into service .................................................................................................................................... 38
Changing the factory settings if necessary............................................................................................... 38
Notes on changing communication parameters “bd.rt, Id.Lo; Id.Hi or GrP”................................................40
Changing the “Id.Lo / Id.Hi” limiter ID.......................................................................................................41
Changing the controller group “GrP”........................................................................................................ 41
Changing the baud rate “bd.rt”................................................................................................................ 41
Setting the “AL.Lo” (low-level alarm = LW) limit....................................................................................... 42
Setting the “AL.Hi” (high-level alarm = HW) limit .....................................................................................42
Calibration to the lower bound of the active measuring range “CAL.L” (0 % calibration value) ..................43
Independent rapid calibration at a water level of > 25 % of the active measuring range “CAL.P”............. 43
Calibration to the upper bound of the active measuring range “CAL.H” (100% calibration value).............44
Setting the filter constant “Filt”................................................................................................................44
Manually initiating a display test.............................................................................................................. 45
Activating URB 2 compatibility “ConP”..................................................................................................... 45
Checking the level display by raising or reducing the level....................................................................... 46
Checking the limiter switchpoints by initiating a test function ..................................................................46
Lockout function...................................................................................................................................... 46
Starting, operation and testing .................................................................................................................... 47
System malfunctions.................................................................................................................................... 51
Causes ....................................................................................................................................................51
Indication of system malfunctions using fault codes................................................................................. 52
Common application and usage errors.....................................................................................................54
Checking installation and function ...........................................................................................................56
Taking out of service.................................................................................................................................... 57
Cleaning the level electrode......................................................................................................................... 58
Cleaning interval...................................................................................................................................... 58
Disposal ........................................................................................................................................................ 58
Returning decontaminated equipment........................................................................................................ 58
EU Declaration of Conformity....................................................................................................................... 59

4NRG 26-61 - Installation & Operating Manual - 819874-00
Content of this Manual
Product:
Level Electrode NRG 26-61
First edition:
BAN 819874-00/08-2019cm
© 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 electrode NRG 26-61
 1 x sealing ring D 27 x 32, form D, DIN 7603-2.4068, bright annealed
 1 x Installation & Operating Manual

5NRG 26-61 - Installation & Operating Manual - 819874-00
How to use this Manual
This Installation & Operating Manual describes the correct use of the NRG 26-61 level electrode.
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

6NRG 26-61 - Installation & Operating Manual - 819874-00
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.

7NRG 26-61 - Installation & Operating Manual - 819874-00
Specialist terms/Abbreviations
Here, we explain some abbreviations, specialist terms, etc., which are used in this Manual.
IEC 61508
International standard IEC 61508 describes both the type of risk assessment and actions taken to provide
appropriate safety functions.
SIL (safety integrity level)
Safety integrity levels SIL 1 to 4 are used to quantify risk reduction. SIL 4 is the highest level of risk
reduction. International standard IEC 61508 forms the basis for establishing, testing and operating
technical safety systems.
CAN (Controller Area Network) bus
Data transmission standard and interface for connecting electronic equipment, sensors and control
systems. Data can be sent and received.
NRG .. / URS .. / URB .. / SRL .. / etc.
Equipment and type designations of GESTRA AG, see page 10.
SELV
Safety Extra Low Voltage
Operating point (of the plant)
The operating point describes the operating parameters within which a plant or boiler is operated in its
nominal range. In a pressurised steam plant, for example, these parameters would be output, 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
temperature of 275 °C, for example, which is not necessarily its operating point.

8NRG 26-61 - Installation & Operating Manual - 819874-00
Usage for the intended purpose
Use as a safety high-level (HW) limiter and low-level (LW) limiter
The NRG 26-61 level electrode is used in conjunction with the URS 60 / URS 61 safety control unit as a
safety high-level limiter and low-level limiter for pressurised steam and hot-water plants.
 Safety high-level limiters prevent the defined maximum high water (HW) level from being exceeded,
e.g. by switching off the feedwater supply.
 Low-level limiters react when the water drops below the set minimum level (LW), e.g. by
switching off the heating.
Safety notes for use as an LW limiter
 Since the electrode measures continuously using capacitance, the low-level limiter function
of the NRG 26-61 may only be used in combination with a conductive NRG 16-60 level
electrode.
 Always use the NRG 16-60 level electrode as the first low-level electrode.
Additional use as a level control system
In addition, the NRG 26-61 level electrode can be used with an NRR 2-60 / NRR 2-61 level controller for
continuously measuring the water level in pressurised steam and hot-water plants or in condensate and
feedwater tanks.
 In combination with the NRR 2-60 / NRR 2-61 level controller, the electrode can be used as a level
control system with MIN/MAX alarm, for example.
 The limiter functions can be disabled independently and by an infinitely variable measurement signal.
Influences of the test fluid
 The NRG 26-61 level electrode can be used in fluids with different conductivity. However, a con-
ductivity of less than 100 μS/cm has a major influence on the measured capacitance, which is why
recalibration of the measuring range (see page 43) at the operating point* and after a cold start is
extremely important.
* Operating point of the plant, see page 7.
 To achieve the best possible reproducibility and maintain high-quality measurements (see “Technical
data” on page 19), the sensor must be installed in a protective tube (see “Installation examples with
dimensions” on page 29 ff.).
 This is the only way to ensure safe use as a level limiter with a SIL 2 rating at the stated values.
 If the dielectric constant of the test fluid differs considerably from that of the usual water used
(Er = 80), it may be necessary to adjust the measuring frequency. For this, please contact the GESTRA
AG Service department.
Visual display and operation
 Viewing and operation take place using the URB 60 or SPECTOR
control operating terminal.

9NRG 26-61 - Installation & Operating Manual - 819874-00
Usage for the intended purpose
Applicable directives and standards
The NRG 26-61 level electrode has been tested and approved for use in the scope governed by the
following directives and standards:
Directives:
 Directive 2014/68/EU EU Pressure Equipment Directive
 Directive 2014/35/EU Low Voltage Directive
 Directive 2014/30/EU EMC Directive
 Directive 2011/65/EU RoHS II Directive
Standards:
 EN 12953-09 Shell boilers, requirements for limiting devices
 EN 12952-11 Water-tube boilers, requirements for limiting devices
 EN 60730-1 Automatic electrical controls – Part 1:
General requirements
 EN 61508 Functional safety of electronic systems
Standards documents:
 VdTÜV Bulletin BP WASS 0100-RL
Requirements for water level control and limiting equipment

10 NRG 26-61 - Installation & Operating Manual - 819874-00
Usage for the intended purpose
Admissible system components, dependent on the required safety level
In accordance with EU Pressure Equipment Directive 2014/68/EU and standards EN12952, EN12953
and EN61508, and the technical rules of VdTÜV Bulletin BP WASS 0100-RL, the level electrode can be
operated with the following system components, as suitable for the required safety integrity level.
Level control and
limiter electrode
Safety control
unit for limiters
Control unit as
level controller and
limit indicator
Operating unit
SIL 2
to
EN 61508
NRG 26-61 URS 60
URS 61 –URB 60,
SPECTOR
control
Without
SIL as per EN
61508
NRG 26-61 – NRR 2-60
NRR 2-61
URB 60,
SPECTOR
control
Fig. 1
Key to Fig. 1:
NRG = level electrode
URS = SPECTOR
connect safety control unit
URB = visual display and operating unit
SRL = monitoring unit
NRR = level controller, continuous
To ensure the proper use of equipment during all types of use, please also read the Installation
& Operating Manuals for the system components used.
 You will find the latest Installation & Operating Manuals for the system components named
in Fig. 1 on our website:
http://www.gestra.com/documents/brochures.html

11NRG 26-61 - Installation & Operating Manual - 819874-00
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.

12 NRG 26-61 - Installation & Operating Manual - 819874-00
Basic safety notes
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 plant before performing connection work.
 Check that the plant is not carrying live voltage before commencing work.
Danger to life from a faulty NRG 26-61 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
NRG 26-61 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 tight when bringing into service.
Attempts to repair the equipment will cause the plant to become unsafe.
 The NRG 26-61 level electrode may only be repaired by the manufacturer, GESTRA AG.
 Only replace faulty equipment with identical equipment from GESTRA AG.

13NRG 26-61 - Installation & Operating Manual - 819874-00
Required personnel qualifications
Activity Personnel
Integration in control system Specialist staff Plant designer
Installation/electrical
connection/bringing into service Specialist staff
The unit is an item of equipment with a
safety function (EU Pressure Equipment
Directive) and may only be installed, electri-
cally connected and brought into service by
suitable, trained 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.
Retrofit Specialist staff Persons trained by the plant operator to work
with pressure and temperature.
Fig. 2
Notes on product liability
We the manufacturer cannot accept any liability for damages resulting from improper use of the equip-
ment.

14 NRG 26-61 - Installation & Operating Manual - 819874-00
Functional safety, safety integrity level (SIL)
In combination with the URS 60 / URS 61 safety control unit, the NRG 26-61 level electrode is suitable for
safety functions up to SIL 2.
It is an element of a safety circuit up to SIL 2 as per EN 61508 in the SPECTOR
connect system, and can
transmit alarm notifications.
When combined with the accessories, you will have a type B subsystem. The technical and safety charac-
teristics in Fig. 4 are based solely on the NRG 26-61 level electrode.
Breakdown of safety function failure rates (safety shutoff)
NRG 26-61
NRG 26-61
mechanical
NRG 26-61
electronic CANopen URS 60, URS 61
Safety circuit 1
Safety circuit 2
The CANopen interface is a “Black Channel” type, and can be ignored during calculation due to
the low failure rate of < 1FIT.
Check the safety function regularly
Check the limiter function of the level electrode at least once a year by bringing the system to the mini-
mum and/or maximum water level (T1 = 1 year), see page 46.
The test function is initiated on site using the rotary knob integrated in the terminal box, see page 50.
In addition, the test function can be initiated remotely on the URS 60 / URS 61 or the external URB 60
or SPECTOR
control operating units.
Fig. 3

15NRG 26-61 - Installation & Operating Manual - 819874-00
Reliability data to EN 61508
Description Characteristic values
Safety integrity level SIL 2
Architecture 1oo1
Type of equipment Type B
Hardware error tolerance HFT = 0
Overall failure rate for dangerous undetected failures λDU = < 20 * 10-9 1/h
Overall failure rate for dangerous detected failures λDD = < 2000 * 10-9 1/h
Safe failure fraction SFF > 99.0 %
Test interval T1 = 1 year
Probability of failure on demand PFD < 100 * 10-6
Diagnostic coverage. Percentage of dangerous failures
detected by a test. DC > 98.0 %
Mean time to failure MTTFD> 30 a
Diagnostic interval T2 = 1 hour
Performance level (to ISO 13849) PL = d
Probability of failure per hour PFH < 20 * 10-9 1/h
Ambient temperature as a basis for calculation Tu = 60 °C
Mean time to repair MTTR = 0 (no repair)
Fraction of undetected dangerous failures that have a
common cause beta = 2 %
Fraction of detected dangerous failures that have a com-
mon cause beta d = 1 %
Fig. 4

16 NRG 26-61 - Installation & Operating Manual - 819874-00
Function
The NRG 26-61 level electrode works using the capacitance measurement principle and converts the
water level information into a data telegram. The 0 - 100 % measuring range can be scaled based on the
effective length of the electrode rod.
Automatic self-test
An automatic self-test cyclically monitors the safety and function of the level electrode and measured
value acquisition.
The data are transferred to the URS 60 / URS 61 safety control unit in the form of a Black Channel data
telegram in the CANopen protocol via an ISO 11898 CAN bus.
These data telegrams contain the following information:
 Measured level value as raw data
 Measured level value scaled between 0 – 100 %, as a 16-bit data word in high resolution
 Measure level value scaled in 1 % stages without decimal places
 Limiter LW/HW alarm limits
 Status or error information
 Fault indications in the event of faults in electronic or mechanical parts
 Temperature in the level electrode terminal box
 LW/HW limiter test command
Limiter functions
If the water exceeds the set high-level point, the URS 60 or URS 61 safety control unit initiates a safety
shutoff. This “High Water (HW)” switchpoint can be adjusted solely using the rotary knob on the
NRG 26-61 level electrode.
If the water falls below the set low-level point, the URS 60 or URS 61 safety control unit initiates a safety
shutoff. This “Low Water (LW)” switchpoint can be adjusted solely using the rotary knob on the NRG 26-61
level electrode.
The level electrode works using the capacitance measurement principle and is equipped with numerous
self-monitoring mechanisms. Faults in the electrical connection or electronic measuring equipment trigger
fault indications and safety shutoffs.
The level electrode is installed inside pressurised steam plants, tanks or feed lines in pressurised
hot-water plants. A protective tube provided on site keeps it functioning reliably (see page 29 “Installa-
tion examples”).
A capacitance NRG 26-61 level electrode and a conductive NRG 1x-60 or NRG 1x-61 level electrode can
be installed in the same protective tube or level pot.
Safety notes for use as an LW limiter
 Since the electrode measures continuously using capacitance, the low-level limiter function
of the NRG 26-61 may only be used in combination with a conductive NRG 16-60 level
electrode.
 Always use the NRG 16-60 level electrode as the first low-level electrode.

17NRG 26-61 - Installation & Operating Manual - 819874-00
Function
Use as a limiter in external mounted level pots
If a level electrode is installed in a lockable level pot outside the boiler, the connecting pipes must be
flushed regularly. An SRL 6-60 monitoring unit is additionally required to monitor the flushing times and
flushing process.
If the steam pipe is ≥ 40 mm and the water pipe is ≥ 100mm, installation is regarded as internal. In this
case, upstream monitoring of flushing processes is not required.
Display and signals, see page 47 / 51 *
The NRG 26-61 level electrode has a green 4-digit, 7-segment display for showing readings, status infor-
mation and fault codes. A red and green LED indicate the operating status.
Behaviour when switched on *
“LO.LE” and “HI.LE” (low and high-level alarm, LW and HW) are shown alternately on the display.
This is due to the factory-set alarm limits “AL.Lo” and “AL.Hi”.
When bringing into service for the first time, you will therefore be asked to change the alarm
limits to suitable values for your specific plant.
To set the “AL.Lo” and “AL.Hi” alarm limits, see page 42.
Behaviour in normal operation (no alarm, no faults) *
The display shows the scaled level reading (3 digits + 1 decimal place), e.g. 050.3
The scale of the 0 – 100 % measuring range is factory-set at a maximum for the electrode
length used. This way, meaningful measurements results of the level can be obtained immedi-
ately after installation.
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 page 43 - 44. This is
the only way to gain all the benefits of a high measurement resolution in the sight glass range.
When the equipment is brought into service for the first time, the “AL.Lo” and “AL.Hi” alarm
limits are set to Max/Min values, which is why the warning messages “LO.LE” and “HI.LE” are
shown alternately on the display.
First, set the “AL.Lo” and “AL.Hi” alarm limits to suitable values for your specific plant, see
page 42.

18 NRG 26-61 - Installation & Operating Manual - 819874-00
Behaviour in the event of an alarm (the level has strayed beyond a limit value) *
“LO.LE” (for LW) or “HI.LE” (for HW) are shown on the display, alternating with the actual level value.
The alarm state is transferred to the URS 60 or URS 61 safety control unit via CAN data telegram. There,
once the time delay has elapsed, the alarm signal triggers the safety shutoff in the safety control unit. The
URS 60 / URS 61 safety control unit does not automatically lock the safety contacts.
Behaviour in the event of malfunctions *
A fault code, e.g. E.005, appears permanently in the display. Fault codes, see page 52.
The faulty state is transferred to the URS 60 or URS 61 safety control unit via CAN data telegram. The fault
indication causes the unit to executed an undelayed safety shutoff. The URS 60 / URS 61 safety control
unit does not automatically lock the safety contacts.
Electrode alarms and faults cannot be acknowledged.
When the alarm or fault is cancelled the display also goes blank, and the URS 60 / URS 61
safety control unit closes the safety contacts once more.
Simulating the alarm state *
The triggering of an alarm can be simulated by pressing the rotary knob of the NRG 26-61, pressing the
appropriate button on the URS 60 / URS 61, or using the URB 60. The equipment will then behave as if a
normal alarm had been triggered.
* The tables on pages 48 - 50 clearly show the relationship between the equipment
status, the display and the alarm 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 38 ff.
Level control functions
In addition, the NRG 26-61 level electrode can be used in conjunction with an NRR 2-60 / NRR 2-61 level
controller to form a level control system. The controller parameters are set solely on the URB 60 visual
display and operating unit.
Function

19NRG 26-61 - Installation & Operating Manual - 819874-00
Technical data
Model and mechanical connection
 Thread G¾ A, EN ISO 228-1, see Fig. 8
Nominal pressure rating, admissible service pressure and temperature
 PN 40 32 bar (g) at 238 °C
Materials
 Terminal box: 3.2581 G AlSi12, powder-coated
 Sheath: 1.4301 X5 CrNi 18-10
 Electrode rod insulation: PTFE
 Screw-in body: 1.4571, X6CrNiMoTi17-12-2
pH value
 Maximum admissible = 10
Max. electrode length at 238 °C, all measurements in mm
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.
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
 Limit error: + 1 % from MAX (AL.Hi)
- 1 % from MIN (AL.Lo)
 MAX hysteresis: - 3 % from limit value
 MIN hysteresis: + 3 % from limit value
 Resolution of reading on display: 0.1 %
 Resolution for internal processing: 15 bits with sign (16 bits)
Supply voltage
 24 V DC +/-20 %
Power consumption
 Max. 7 VA

20 NRG 26-61 - Installation & Operating Manual - 819874-00
Technical data
Current input
 Max. 0.3 A
Internal fuse
 T2A
Safety cutout at excessive ambient temperature
 The cutout at excessive ambient temperature takes place at Tamb. = 75 °C
Input/output
 Interface for CAN bus to ISO 11898, CANopen, insulated
 M12 CAN bus connector, 5-pole, A-coded
 M12 CAN bus socket, 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 alarm
 1 x green LED for indicating OK
 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
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
 Approx. 2.1 kg
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.