GESTRA NRG 16-12 User manual

1
NRG 16-12
NRG 17-12
NRG 19-12
Installation Instructions 818626-02
Level Electrode
NRG 16-12, NRG 17-12, NRG 19-12
GESTRA Steam Systems
EN
English

2
Inhalt
Usage for the intended purpose ..............................................................................................................4
Safety note .............................................................................................................................................4
Danger ...................................................................................................................................................4
Attention.................................................................................................................................................4
ATEX (Atmosphère Explosible).................................................................................................................4
Important Notes
Page
Explanatory Notes
Scope of supply......................................................................................................................................5
Description .............................................................................................................................................5
Function .................................................................................................................................................6
System components ...............................................................................................................................6
Design....................................................................................................................................................6
NRG 16-12, NRG 17-12, NRG 19-12, step 1..........................................................................................15
NRG 16-12, NRG 17-12, NRG 19-12, step 2..........................................................................................15
Attention...............................................................................................................................................15
Important notes ....................................................................................................................................16
Tools.....................................................................................................................................................16
Installation
NRG 16-12, NRG 17-12, NRG 19-12 .......................................................................................................7
Corrosion resistance...............................................................................................................................8
Sizing .....................................................................................................................................................8
Name plate / marking .............................................................................................................................8
Dimensions NRG 16-12, NRG 17-12 .......................................................................................................9
Dimensions NRG 19-12 ........................................................................................................................10
Technical Data
NRG 16-12, NRG 17-12, NRG 19-12 .....................................................................................................11
Key.......................................................................................................................................................14
Design
NRG 16-12, NRG 17-12, NRG 19-12 .....................................................................................................12
Optional for NRG 16-12, NRG 17-12, NRG 19-12 ..................................................................................13
Key.......................................................................................................................................................14
Functional Elements
NRG 16-12, NRG 17-12, NRG 19-12 .....................................................................................................17
Key.......................................................................................................................................................18
Examples of Installation

3
Contents – continued –
Electrical Connection
NRG 16-12, NRG 17-12, NRG 19-12 .....................................................................................................19
Optional for NRG 16-12, NRG 17-12, NRG 19-12 ..................................................................................19
Wiring diagram.....................................................................................................................................20
Voltage table.........................................................................................................................................21
Note .....................................................................................................................................................21
Tools.....................................................................................................................................................21
Checking electrical connection .............................................................................................................21
Applying mains voltage.........................................................................................................................21
Commissioning
Page
Danger .................................................................................................................................................23
Disposal................................................................................................................................................23
Decommissioning
High-level alarm ...................................................................................................................................22
Note .....................................................................................................................................................22
Operation
Fault-finding list for troubleshooting......................................................................................................22
Operational Malfunctions

4
Important Notes
Danger
When loosening the electrode steam or hot water might escape.
This presents the danger of severe scalds to the whole body.
It is essential not to mount or dismantle the electrode unless the boiler pressure is
verified to be 0 bar. The electrode becomes hot during operation. Touching the hot
equipment presents the risk of severe burns to hands and arms. All installation and
maintenance work must only be performed when the equipment is cold.
Usage for the intended purpose
Use level electrodes NRG 16-12, NRG 17-12 and NRG 19-12 only in conjunction with level switch
NRS 1-8 for high water-level limiting (MAX alarm). The equipment must not be used in explosion-risk
areas.
Safety note
The equipment must only be installed and commissioned by qualified and competent staff.
Retrofitting and maintenance work must only be performed by qualified staff – who through adequate
training – have achieved a recognised level of competence.
ATEX (Atmosphère Explosible)
The equipment constitutes a simple item of electrical equipment as defined in DIN EN 50020 section
5.4. According to the European Directive ATEX 94/9/EC the equipment may only be used in potentially
explosive atmospheres if it is provided with approved Zener barriers.
Applicable in Ex zones 1, 2 (1999/92/EC). The equipment does not bear an Ex marking. The suitability
of the Zener barriers is certified in a separate document.
Attention
The name plate specifies the technical features of the equipment. Note that any piece of
equipment without its specific name plate must neither be commissioned nor operated.

5
Explanatory Notes
Scope of supply
NRG 16-12
1 Level electrode NRG 16-12, PN 40
1 Joint ring 27 x 32, form D, DIN 7603, 1.4301, bright-annealed
1 Disk with set screw (measuring surface extension) – optional
1 Retaining ring – optional
1 Installation manual
NRG 17-12
1 Level electrode NRG 17-12, PN 63
1 Joint ring 27 x 32, form D, DIN 7603, 1.4301, bright-annealed
1 Disk with set screw (measuring surface extension) – optional
1 Retaining ring – optional
1 Installation manual
NRG 19-12
1 Level electrode NRG 19-12, PN 160
1 Joint ring 27 x 32, form D, DIN 7603, 1.4301, bright-annealed
1 Disk with set screw (measuring surface extension) – optional
1 Retaining ring – optional
1 Installation manual
Description
The level electrode NRG 1...-12 detects the max. liquid level (high level alarm) in a steam boiler.
The operation of the electrode is based on the conductivity measuring principle using the electrical
conductivity of water for signaling one liquid level:
n High level alarm (MAX alarm)
The NRG 1...-12 is designed for use in conjunction with level switch NRS 1-8 as a self-monitoring low
level limiter with periodic self-checking (SMART) feature.
Application in steam and pressurised hot-water plants in accordance with TRD 604, sheet 1 and
sheet 2 (24 h/72 h operation).
The electrical equipment meets the requirements of the Regulations on Protection Circuits
EN 50156-1.

6
Design
NRS 16-12, NRG 17-12, NRG 19-12
Mechanical connection: Screwed ¾", ISO 228-1
Electrical connection: Four-pole connector/terminal box made from aluminium (optional)
Explanatory Notes – continued –
Function
The high water-level limiter comprises a level electrode type NRG 1...-12 and a level switch type NRS
1-8. The level electrode NRG 1...-12 consists of a pressure-tight measuring electrode. The electrode is
insulated with a plastic sleeve.
The high water-level limiter is based on the conductive measuring principle using the electrical
conductivity of water for signaling water level. During normal, trouble-free operation the level electrode
tip is not immersed in boiler water and no high level alarm is given. A high level alarm will only be
raised if the electrode tip is submerged for more than 3 seconds. A high level alarm will also be
activated if the insulating seals placed between the electrodes and the body are no longer pressure
tight, allowing water to penetrate into the body. However in this instance the alarm is caused by a
malfunction of the electrode, and confirmation should always be done by checking the water level in the
gauge glass. The equipment combination NRG 1...-12 and NRS 1-8 provides fail safe protection against
a first fault in accordance with TRD 604.
System components
NRS 1-8
Level switch NRS 1-8. Two channel level limiter (redundancy) with periodic self-checking routine to
EN 50156-1.

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NRG 16-12, NRG 17-12, NRG 19-12
Technical Data
Type approval
TÜV · HWS · 08-417
Service pressure
NRG 16-12: 32 bar at 238 °C
NRG 17-12: 46 bar at 260 °C
NRG 19-12: 100 bar at 311 °C
Connection
¾" BSP, ISO 228-1
Materials
Sheath: 1.0715, 11SMn30
Screwed union: 1.4571 X6CrNiMoTi17-12-2
Measuring electrode: 1.4401, X5CrNiMo17-12-2
Electrode insulation: PEEK
Four pole connector: Polyamide (PA)
Terminal box: 3.2161 G AlSi8Cu3 (optional)
Lengths available
500 mm
1000 mm
1500 mm
Cell constant C
0.13 cm-1 with measuring surface extension
0.3 cm-1 without measuring surface extension
Response sensitivity
10 µS/cm at 25 °C, cell constant 0.3 cm-1
0.5 µS/cm at 25 °C, cell constant 0.13 cm-1
Electrical connection
Four-pole connector, cable gland M 16
Terminal box made from aluminium, cable gland M 16 (optional)
Protection
IP 65 to EN 60529
Max. admissible ambient temperature
70 °C
Weight
Approx. 1.1 kg

8
Corrosion resistance
Provided that the equipment is used for its intended purpose, its safety is not impaired by
corrosion.
Technical Data – continued –
Sizing
The body must not be subjected to pulsating stress. Welds and flanges of the electrode are designed to
withstand dynamic loading (bending and alternating stress). The dimensional allowances for anti-cor-
rosive additives reflect the latest state of the technical art.
Name plate / marking
Equipment designation
Fig. 1
Fig. 2 Fig. 3

9
Technical Data – continued –
Dimensions NRG 16-12, NRG 17-12
Fig. 4
NRG 16-12 with
measuring surface extension
Fig. 5
NRG 17-12 without
measuring surface extension
8
165
85
≤1500
23
30
272
85
≤1500
30
¾, ISO 228-1 ¾, ISO 228-1

10
Technical Data – continued –
Dimensions NRG 19-12
Fig. 6
NRG 19-12 without
measuring surface extension
283120
≤1500
30
¾, ISO 228-1

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Design
NRG 16-12, NRG 17-12, NRG 19-12
Fig. 9 Fig. 10
Fig. 7 Fig. 8
N 8
N 10 0.5
¾, ISO 228-1
∅33
9
80
a
1
2
3
4
5
7
6

12
Functional Elements
NRG 16-12, NRG 17-12, NRG 19-12
Fig. 11
i
h
f
e
b
c
d
g

13
Functional Elements – continued –
Optional for NRG 16-12, NRG 17-12, NRG 19-12
Fig. 13
Fig. 12
j k l k
m
n o

14
1Measuring electrode
2Bore
3Spring
4Electrode tip
5Grub screw
6Disk (measuring surface extension)
7Retaining ring
8Joint ring 27 x 32, form D, DIN 7603, 1.4301, bright-annealed
9Seating surface
0Electrode thread
!Thermal insulation, provided on site, d = 20 mm
(outside of thermal insulation of steam generating unit)
"Screw M 4
§Cover
$Upper part of terminal box
%Connecting plate
&Sealing element
/Contact plate for level electrode
(Cable clamp
)Cable gland M 16 (PG 9)
=Housing screws M 4
aCable entry M 20 x 1.5
bHousing cover
cNut
dPE connection
eTerminal strip
Design / Functional Elements – continued –
Key

15
Attention
nThe seating surfaces and threads on the vessel and mounting flange must be accurately
machined, Fig. 10
nUse GESTRA PN 160 hat flange when applying the equipment in a high-pressure steam
boiler.
nDo not bend the electrode tip when cutting.
nUse only the supplied ring joint 27 x 32, form D, DIN 7603, 1.4301, bright-annealed.
nDo not lag the electrode body.
nDo not insulate the threads with hemp or PTFE tape.
nDo not apply conductive paste or grease to the electrode thread.
nProvide a min. spacing of 14 mm between electrode and earth (flange, boiler wall).
nObserve the minimum distances for the installation of the electrode.
Installation
NRG 16-12, NRG 17-12, NRG 19-12, step 1
1. Screw electrode tip 4into measuring electrode 1, Fig. 7
2. Carefully determine required measuring length, taking minimum length into account.
3. Mark length of electrode tip 4.
4. Unscrew electrode tip 4from measuring electrode 1and cut tip.
5. Screw electrode tip 4into measuring electrode 1and tighten. Slide spring 3along electrode tip
4, so that its bent end completely enters into small bore 2.
6. If a measuring surface extension is required slip disk 6onto electrode tip 5ensuring that the
electrode tip protrudes 2 mm from the bottom of the disk. Fasten disk with set screw 7.
Push star-lock washer 6over electrode tip against disk.
NRG 16-12, NRG 17-12, NRG 19-12, step 2
1. Check seating surfaces, Fig. 10
2. Place joint ring 8onto seating surface 9of electrode, Fig. 8
3. Apply a light smear of silicone grease (e. g. Molykote®111) to electrode thread 0.
4. Screw level electrode into threads of flange provided on vessel and tighten with a 36 mm ring
spanner. The torque required is 160 Nm when cold.
Molykote®111 is a registered trademark of DOW Corning Corp., Midland Michigan, USA

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Important notes
nFor the approval of the boiler standpipe the relevant regulations must be observed.
nFor typical installation examples refer to page 17.
nWhen mounting the electrode laterally make sure that the inclination angle does not
exceed 45° and that the length of the electrode rod is limited to 1000 mm. Fig. 15
nIf the electrode is installed outdoor, it must be provided with a weather-proof cover
supplied by GESTRA. Alternatively the electrode can be provided with a terminal box
made from aluminium.
Tools
nOpen-end spanner A. F. 13, DIN 3110, ISO 3318
nOpen-end spanner A. F. 36, DIN 3110, ISO 3318
nScriber
nHacksaw
nFlat file, cut 2, DIN 7261, form A
Installation – continued –

17
Examples of Installation
NRG 16-12, NRG 17-12, NRG 19-12
DN 100
Fig. 16
∅20
20
≥ DN 20
24.5 24.5
20
∅20
Fig. 14
Fig. 17
DN 50
¾
¾
¾
≤ 20
≤ 3000
∅20
≤ 90°
∅20
¾
≤ 90°
Centre distance
Fig. 15
≥14
≥ DN 20
≥DN 20
p
q
r
s
t
max. 1000
20
45°
p
q
t
s
r
p
s
t
≥ 10
s
w
u
x
y
x
y
v
w
x

18
Examples of Installation – continued –
Key
pFlange PN 40, PN 63, PN 160, DN 50, DIN 2501-1 (single electrode)
Flange PN 40, PN 63, PN 160, DN 100, DIN 2501-1 (for 2 electrodes installed in one flange)
qFor the approval of the boiler standpipe the relevant regulations must be considered.
rVent hole Provide bore as close as possible to the boiler wall!
sHigh water HW
tElectrode rod d = 8 mm
uProtection tube DN 80, ≥ DN 100 according to French regulations
vProtection tube DN 100
w Electrode distance ≥ 14 mm (creepage distances and clearances)
xLow water LW
yReducer DIN 2616-2, K-88.9 x 3.2 – 42.4 x 2.6 W

19
Electrical Connection
NRG 16-12, NRG 17-12, NRG 19-12
Wiring via four-pole connector.
Screened four-core cable, e. g. I-Y(St)Y 2 x 2 x 0.8 or LIYCY 4 x 0.5 mm² is required for wiring the
electrode.
Max. length 100 m with conductivites from 10 µS/cm.
Max. length 30 m with conductivites from 0.5 µS/cm.
Max. length 15 m with conductivites from 0.5 µS/cm and application of the ancillary unit URN 1
(24 V DC).
1. Unscrew screw ",Fig. 11
2. Take the terminal box off the level electrode, leaving the sealing element &on the contact
plate /.
3. Remove cover §.
4. Press connecting plate %out of the upper part of the terminal box $.
The upper part of the terminal box can be turned in steps of 90°.
5. Detach cable gland )and cable clamp (from the upper part of the terminal box $.
6. Run cable through cable gland )and upper terminal box $and connect the terminals of the
connecting plate %according to the wiring diagram.
7. Press connecting plate %into the upper part of the terminal box and align the cable.
8. Hold cable with cable clamp (and cable gland )in position.
9. Mount lid §and insert screw ".
10. Put upper part of the terminal box onto the level electrode and fix it firmly with screw ".
Optional for NRG 16-12, NRG 17-12, NRG 19-12
Wiring via terminal box made from aluminium.
Screened four-core cable, e. g. I-Y(St)Y 2 x 2 x 0.8 or LIYCY 4 x 0.5 mm² is required for wiring the
electrode.
Max. length 100 m with conductivites from 10 µS/cm.
Max. length 30 m with conductivites from 0.5 µS/cm.
Max. length 15 m with conductivites from 0.5 µS/cm and application of the ancillary unit URN 1
(24 V DC).
1. Unscrew housing screws =and remove cover b. Fig. 12
2. Unscrew union nut of cable entry a.
3. Loosen nut cwith 18 mm open-end spanner but do not remove it! Fig. 13
The electrode terminal can be turned through +/– 180°.
4. Turn electrode into desired direction (+/– 180°).
5. Slightly tighten nut c.
6. Detach terminal strip efrom board.
7. Wire terminal strip in accordance with the wiring diagram.
8. Re-attach terminal strip.
9. Replace housing cover band fasten screws =.

20
Electrical Connection – continued –
Wiring diagram
Fig. 18
Fig. 20
This wiring diagram is only valid for France.
Fig. 19
L N
Safety chain
L N
Safety chain