GESTRA NRGT 26-1S Service manual


GESTRA Steam Systems
GESTRA
NRGT 261
NRGT 261S
Installation Instructions 81021304
Level electrode
NRGT 26-1, NRGT 26-1 S

2
Contents
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
System description .................................................................................................................................5
Function .................................................................................................................................................5
Designs ..................................................................................................................................................5
NRGT 26-1 ...........................................................................................................................................13
NRGT 26-1S .........................................................................................................................................13
Attention...............................................................................................................................................13
Note .....................................................................................................................................................13
Tools.....................................................................................................................................................13
Examples of installation ........................................................................................................................14
Key.......................................................................................................................................................15
Installation
NRGT 26-1, NRGT 26-1S ....................................................................................................................6, 7
Corrosion resistance...............................................................................................................................7
Sizing .....................................................................................................................................................7
Name plate / marking .............................................................................................................................8
Dimensions.............................................................................................................................................9
Technical Data
NRGT 26-1, NRGT 26-1S ......................................................................................................................10
Key.......................................................................................................................................................12
Design
NRGT 26-1, NRGT 26-1S ......................................................................................................................11
Key.......................................................................................................................................................12
Functional Elements

3
Wiring
NRGT 26-1, NRGT 26-1S ......................................................................................................................16
Wiring diagram.....................................................................................................................................16
Attention...............................................................................................................................................16
Tools.....................................................................................................................................................16
Danger .................................................................................................................................................18
Check wiring ........................................................................................................................................18
Apply mains voltage..............................................................................................................................18
Adjust lower measuring range ..............................................................................................................18
Adjust upper measuring range..............................................................................................................18
Note .....................................................................................................................................................18
Contents – continued –
Commissioning
Page
Danger .................................................................................................................................................21
Disposal................................................................................................................................................21
Decommissioning
NRGT 26-1, NRGT 26-1S ......................................................................................................................19
Note .....................................................................................................................................................19
Operation
Fault finding list for troubleshooting......................................................................................................20
Operational Malfunctions
Factory setting NRGT 26-1....................................................................................................................17
Factory setting NRGT 26-1S..................................................................................................................17
Establish active measuring range (control range) ..................................................................................17
Attention...............................................................................................................................................17
Basic Setting
Declaration of conformity......................................................................................................................22
Annex

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.
The terminal strip of the NRGT 26-1 / NRGT 26-1S is live during operation.
This presents the danger of electric shock.
Cut off power supply before fixing or removing the housing cover.
Usage for the intended purpose
Use level electrodes NRGT 26-1 and NRGT 26-1S only for indicating liquid levels.
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)
According to the European Directive 94/9/EC the equipment must not be used in potentially explosive
areas.
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
System description
The compact system NRGT 26-1 works according to the capacitance measurement principle.
The NRGT 26-1 is used for signalling different levels in electrically conductive and non-conductive
liquids:
■ Level maintained within the control band defined by two preset limits
The NRGT 26-1 has a level transmitter integrated in the electrode body which produces a standard
signal of 4 -20 mA. External switchgear is not required.
Function
Designs
The principle of capacitance measurement is applied to determine the level. The electrode rod and
the vessel wall form a capacitor. If the level of the dielectric located between the two capacitor plates
changes, the current which flows through the plates changes proportionally to the level. A dielectric
is defined as an insulating substance, which excludes many liquids such as water. In order to receive
a useful measuring result the measuring rod, which is submerged to varying depths in the liquid,
must be completely insulated. After the calibration of the zero point/measuring range (0 %/100 %)
the level can be read off from a remote display unit. The level measuring range can be changed
during operation.
NRGT 261:
Screwed design ¾" BSP, DIN ISO 228-1. Fig. 2
NRGT 261S:
Flanged design for marine application DN 50, PN 40, DIN 2635. Fig. 3
Scope of supply
NRGT 261
1 Compact system type NRGT 26-1
with joint ring (of stainless steel 1.4301) D 27 x 32 to DIN 7603, bright annealed
1 Installation manual
NRGT 261S (for marine applications)
1 Compact system type NRGT 26-1S with flange DN 50 (2"), PN 40 to DIN 2635
1 Installation manual

6
See Fig. 2
NRGT 261, NRGT 261S
Technical Data
Type Approval N°
NRGT 26-1: TÜV · WRS · 02-391
NRGT 26-1S: LR 98/20075 RINA ELE/30298/2
GL 99249-96HH BV 10617/AO BV
NKK A-556 DNV A-8394
KR HMB 06190-MS002
Max. service pressure
32 bar g at 238 °C
Connections
NRGT 26-1: Screwed ¾" BSP, DIN ISO 228-1
NRGT 26-1S: Flanged DN 50, PN 40, DIN 2635
Materials
Case: Die cast aluminium 3.2161 (G AlSi8Cu3)
Stem: S. S. 1.4571 CrNiMoTi17-12-2
Flange: Forged steel 1.0460 P250GH
Measuring electrodes: S. S. 1.4571 CrNiMoTi17-12-2
Electrode insulation: PTFE
Spacer disc: PTFE (design for marine applications)
Mains supply
230 V +/- 10 %, 50/60 Hz
115 V +/- 10 %, 50/60 Hz (option)
224 V +/- 10 %, 50/60 Hz (option)
24 V DC
Length supplied / measuring range
NRGT 261
1Max. installation length at 238 °C
2Measuring range
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
2000
275
375
475
575
675
775
875
975
1075
1175
1275
1375
1475
1975
316
420
526
631
737
842
947
1053
1157
1262
1366
1471
1579
2099
373
477
583
688
794
899
1004
1110
1214
1319
1423
1528
1636
2156
NRGT 261 S
3Max. installation length at 238 °C
4Measuring range
1 2 3 4
See Fig. 3

7
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 sharp increases in pressure. Welds and flanges of the electrode are
designed to withstand dynamic loading (bending and alternating stress). The dimensional allowances
for corrosion reflect the latest state of technology.
NRGT 261, NRGT 261S – continued –
Power consumption
5 VA, 3 VA at 24 V DC
Fuse
Thermal fuse Tmax = 102 °C
Sensitivity
Range 1: Water ≥0,5 µS/cm
Range 2: Water ≥20 µS/cm
Range 3: Fuel oil EL εr2,3
Output
4 – 20 mA level-proportional; electrically insulated, max. load 500 Ω
Indicators and adjustors
2 red LEDs for “level 0 %” or “level 100 %” within the measuring range,
1 green LED for “level between 0 % and 100 %” of measuring range,
1 code switch for selecting the measuring range,
2 trimmer potentiometers for small-percentage adjustment of the measuring range,
2 terminal lugs for voltage measurement.
Cable entry
Cable gland with integral cable clamp
2 x M20 x 1.5
Protection
IP 65 nach DIN EN 60529
Max. admissible ambient temperature
70 °C (158 °F)
Weight
NRGT 26-1: approx. 1.8 kg
NRGT 26-1S: approx. 8.0 kg

8
Technical Data – continued –
Name plate / marking
Fig. 1
PN 40PN 40
PN 40PN 40
IP 65IP 65
PmaxPmax
TmaxTmax
NRGT 26-1
NRGT 26-1S
TÜV . WRS.
02-391
G ¾ 1.4571
DN 50 1.4571/1.0460DN 50 1.4571/1.0460
250 V ~ T 2,5 A250 V ~ T 2,5 A
Before removing cover
isolate from power supplies
See installation instructions
Before removing cover
isolate from power supplies
See installation instructions
Avant d'ouvrir le couvercle
dèconnecter complètement
l'appareil
Voir instructions de
montage
Avant d'ouvrir le couvercle
dèconnecter complètement
l'appareil
Voir instructions de
montage
32 bar (464psi)
238°C (453°F)
Tmax
70°C
(133°F)
Tmax
70°C
(133°F)
GL 99249-96 HH
Vor Öffnen des Deckels
Gerät freischalten!
Betriebsanleitung
beachten
Vor Öffnen des Deckels
Gerät freischalten!
Betriebsanleitung
beachten
50 / 60 Hz 5VA
GB Reg. Design 2 053 113
US Pat. 5 719 342, Design 383 403
GB Reg. Design 2 053 113
US Pat. 5 719 342, Design 383 403
H= __________ mm
4 - 20 mA / 500 
24 V 230 V115 V
GESTRA AG, D-28215 Bremen
24 VDC
IP 65IP 65
PmaxPmax
TmaxTmax
NRGT 26-1
TÜV . WRS.
02-391
PN 40 G ¾ 1.4571
250 V ~ T 2,5 A250 V ~ T 2,5 A
Before removing cover
isolate from power supplies
See installation instructions
Avant d'ouvrir le couvercle
dèconnecter complètement
l'appareil
Voir instructions de
montage
32 bar (464psi)
238°C (460°F)
Tmax
70°C
(158°F)
GL 99249-96 HH
Vor Öffnen des Deckels
Gerät freischalten!
Betriebsanleitung
beachten
H= __________ mm
4 - 20 mA / 500 
Ser.-Nr.: 316141
0525
GESTRA AG
Münchener Str. 77
D-28215 Bremen
3VA
Vers.XX

9
42
Flansch
PN 40, DN 50
62 ~338
140
173
GESTRA Steam Systems
GESTRA
NRGT 26-1S
G 3/4
ISO 228-1
173
140
26 37
1
Tiefe: 70 mm
42
GESTRA Steam Systems
GESTRA
NRGT 26-1
~338
337,5
339
173
140
173
62
140
3 4
b = 70
b = 70
∅42
¾" BSP
37
1 2
26
Flange DN 50, PN 40
∅42
Technical Data – continued –
Dimensions
Fig. 3Fig. 2
2, 4constant length (no elongation)
A.F.

10
GESTRA Steam Systems
GESTRA
NRGT 26-1S
GESTRA Steam Systems
GESTRA
NRGT 26-1
Design
Fig. 4
Fig. 6
N 1
N 10
0.5
∅ 33
¾" BSP DIN 228
NRGT 261,NRGT 261S
A.F.
A
C
B
G
F
E
D
A
Fig. 5

11
Functional Elements
NRGT 261,NRGT 261S
NH
GESTRA
NRGT 26-1
GESTRA Steam Systems
1
2
3
4
6
7
8
9
0
5
1 2 3 4 5
Q
L
Fig. 8
Fig. 7
H I J I
K
L
M N O
P
Q
R
U
T S
Shown:
24, 115, 230 V AC version

12
AThermal insulation provided on site, d = 20 mm (without thermal insulation of steam boiler)
BSeating surface
CJoint ring (of stainless steel 1.4301) D 27 x 32 to DIN 7603
DElectrode thread ¾" BSP, DIN ISO 228-1
EFlange DN 50 (2"), PN 40 to DIN 2635
FProtection tube
GSpacer disc
HHousing screws M4
ICable entry M20 x 1.5
JHousing cover
KMeasuring range switch
LPotentiometer for lower measuring point (4 mA)
MLED “Level 0 %”
NLED “Level > 0 %, <100 %”
OLED “Level 100 %”
PPotentiometer for upper measuring point (20 mA)
QTerminal lugs for voltage measurement (between 0-7 V DC, level proportional)
RThermal fuse Tmax 102 °C
STerminal strip
TPE connection
UPlug
Key
1NRGT 26-1: Max. length of installation at 238 °C
2NRGT 26-1: Measuring range
3NRGT 26-1S: Max. length of installation at 238 °C
4NRGT 26-1S: Measuring range
Design / Functional Elements

13
Attention
■The seating surfaces of the threads or flange provided on the vessel or boiler standpipe
must be accurately machined. Fig. 6
■Do not bend electrode rod when mounting.
■Do not lag electrode body.
■Do not insulate electrode thread with hemp or PTFE tape.
Installation
NRGT 261
1. Check seating surfaces of threads or flange provided on vessel or boiler standpipe. Fig. 6
2. Place joint ring Conto seating surface Bof the electrode Fig. 7.
Use only joint ring (of stainless steel 1.4301) D 27 x 32 to DIN 7603 supplied with electrode.
3. Apply a light smear of silicone grease (e. g. DOW Corning 111 Compound) to electrode thread A.
4. Screw level electrode into threads or flange provided on vessel or boiler standpipe and tighten with
a 41 mm open-end spanner. The torque required is 160 Nm when cold.
NRGT 261S
1. Check seating surfaces and place flat gasket on connection standpipe.
2. Place flange Etogether with level electrode onto connection standpipe and secure with bolts.
Tighten bolts in diagonally opposite pairs. Fig. 5
Note
■For the approval of the boiler standpipe with connecting flange the relevant local or
national regulations must be considered.
■See four examples of installation on page 14.
Tools
■Open-end spanner 17 mm A. F.
■Open-end spanner 41 mm A. F.

14
Installation – continued –
1
DN 100
Fig. 11
∅20 20
24.5 24.5
∅20
Fig. 9 Fig. 10
DN 50
≤ 90°
DN 50
¾" BSP
¾" BSP
¾" BSP ¾" BSP
≥10
∅20
≤ 90°
≤ 90°
∅ 20
∅
20
20
≥10
∅20
DN 20
DN 20
Fig. 12
≤20
¾" BSP
≤10
20
≤1500
centre distance
2
3
4
6
0
!
5
1
2
9
3
5
4
1
5
4
0
2
DN 20
1
2
3
4
6
0
!
5
Examples of installation
8
0
7
"

15
1Flange PN 40, DN 50 (2"), DIN 2527
Flange PN 40, DN 100 (4"), DIN 2527
2For the approval of the boiler standpipe with connecting flange the relevant
regulations must be considered.
3Vent hole
4High water (HW)
5Electrode rod d = 15 mm
6Protection tube DN 80
7Protection tube DN 100
8Electrode distance ≥14 mm (LW)
9Electrode distance ≥40 mm (LW)
0Low water (LW)
!Reducer K-88.9 x 3.2-42.4 x 2.6 W to DIN 2616, part 2
"Reducer K-114.3 x 3.6-48.3 x 2.9 W to DIN 2616, part 2
Key
Installation – continued –

16
Wiring
Use multi-core flexible control cable with min. conductor size 1.5 mm2for wiring.
1. Undo screws H, remove housing cover J. Fig. 7
2. Unscrew union nuts of cable entry I.
The electrode terminal can be turned through +/– 180 °.
3. Loosen plug Uwith 17 mm spanner but do not remove. Fig. 8
4. Turn electrode terminal into desired direction (+/– 180 °).
5. Tighten plug Uslightly.
6. Remove terminal strips Sfrom board.
7. Connect terminal strip according to wiring diagram, connect PE connection T.
8. Plug in terminal strips S.
9. Install cable entry I.
10. Replace housing cover J, insert screws Hand fasten.
NRGT 261,NRGT 261S
■Fuse supply cables with 250 mA (slow blow).
Tools
Attention
Wiring diagram
■Screwdriver for cross head screws, size1
■Screwdriver for slotted screws, size 2.5; completely insulated according to DIN VDE 0680-1
■Open-end spanner 17 mm A. F.
Fig. 13
Thermal fuse
Mains
24 V DC
4-20 mA
Max. load
500 Ω
Earthing screw
in enclosure
NRGT 261
NRGT 261S

17
Basic Setting
Factory setting NRGT 261
The compact system is delivered with the following factory set default values:
■Measuring range 1300 mm: Switch Kposition 4, water ≥20 µS/cm
■Measuring range 1400 mm up to 1700 mm: Switch Kposition 4, water ≥20 µS/cm
■Measuring range 1800 mm up to 1500 mm: Switch Kposition 4, water ≥20 µS/cm
■Measuring range 1600 mm up to 2000 mm: Switch Kposition 5, water ≥20 µS/cm
XControl range [mm] (active measuring range)
2Max. measuring range at 25 °C
5Water, conductivity ≥20 µS/cm
6Water, conductivity ≥25 µS/cm
7Fuel oil EL, dielectric constant εr2.3
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
3
3
3
4
4
4
4
4
5
5
5
5
5
5
5
5
6
6
6
6
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
4
4
4
Lower measuring
point
26
Attention
■If Xis clearly smaller than 2set switch Kone step back.
Establish active measuring range (control range)
A control range may be established within the measuring range of the electrode. Establish the length
of the control range using switch K, see Fig. 8
Factory setting NRGT 261S
The compact system is delivered with the following factory set default values:
■Measuring range 1275 mm: Switch Kposition 4, water ≥20 µS/cm
■Measuring range 1375 mm up to 1675 mm: Switch Kposition 4, water ≥20 µS/cm
■Measuring range 1775 mm up to 1475 mm: Switch Kposition 4, water ≥20 µS/cm
■Measuring range 1575 mm up to 1975 mm: Switch Kposition 5, water ≥20 µS/cm
Fig. 14
37
X567
X
2
K

18
1. Fill boiler or vessel with liquid until the lower measuring point is reached.
2. Wait until boiler or vessel has reached its service pressure.
3. Turn potentiometer Lto the left until the red LED Mlights up.
4. Turn potentiometer Lto the right until only the green LED Nlights up.
You have now established the lower measuring point.
Adjust lower measuring range
Commissioning
Danger
1. Check whether the system NRGT 26-1, NRGT 26-1S has been wired according to wiring diagram
Fig. 13.
2. Check whether mains supply corresponds to the wiring carried out on the equipment.
The terminal strip and the electronic components of the NRGT 26-1/NRGT 26-1S are live
during operation.
This presents the danger of electric shock.
Use only completely insulated screwdriver according to VDE 0680 for adjusting the
measuring points.
Check wiring
1. Turn on power to the equipment. The LED Mof the electrode NRGT 26-1 will light up
(if the electrode is exposed). Fig. 6
Apply mains voltage
1. Fill boiler or vessel with liquid until the upper measuring point is reached and wait for
30 secs. (internal attenuation).
2. Turn potentiometer Pto the right until only the red LED Olights up.
3. Turn potentiometer Pto the left until the green LED Nlights up.
4. Turn potentiometer Pto the right until the green LED Ngoes out.
You have now established the upper measuring point.
5. Fix housing cover J.
Adjust upper measuring range
■When adjusting the measuring points of the electrode in a cold liquid, the measuring
points will shift with rising temperature as a result of the longitudinal expansion of the
electrode rod. Be sure to correct the settings accordingly.
■ If a higher accuracy (for 0 % = 4 mA and 100 % = 20 mA) than ± 0.5 mA is required,
measure the level-proportional current at terminals 1 üand 2 äin order to establish
more accurate settings.
Note

19
Operation
Operation in steam and (pressurised) hot water plants in accordance with TRD 401, TRD 602, TRD 604,
EN 12952, EN 12953 or other national regulations or according to the guidelines of classification
societies.
NRGT 261, NRGT 261S
Note
■Should malfunctions occur during the commissioning procedure refer to chapter
“Operational Malfunctions” on page 20 in order to analyse and correct them.

20
Operational Malfunctions
If faults occur that are not listed above, please contact our subsidiary or agency in your country.
Fault finding list for troubleshooting
Equipment fails to work
Fault: Mains voltage has not been applied.
Remedy: Apply mains voltage. Wire equipment according to the wiring diagram.
Fault: The thermal fuse has been activated.
Remedy: In case of a defective thermal fuse the mains voltage has not been applied to terminal R.
Replace defective thermal fuse (ref. no. 051629).
The ambient temperature must not exceed 70 °C.
Fault: The electrode housing does not have earth connection to the vessel.
Remedy: Clean seating surfaces and insert metal joint ring (of stainless steel 1.4301) D 27 x 32 to
DIN 7603.
Do not insulate compact system with hemp or PTFE tape!
Fault: Electronic board is defective.
Remedy: Replace board (ref. no. 391360).
Equipment does not work accurately
Fault: Electrode has been installed without protection tube.
The protection tube serves as reference electrode.
Remedy: Install protection tube.
Fault: The vent hole in the protection tube does not exist, is obstructed or flooded.
Remedy: Check protection tube and, if necessary, provide vent hole.
Fault: The isolating valves of the external measuring pot (optional) are closed.
Remedy: Open isolating valves.
Fault: The desired zero point does not lie within the measuring range of the electrode.
The electrode is too short.
Remedy: Replace the compact system. Choose adequate electrode length.
Fault: The adjustment of the measuring range is wrong.
Remedy: Adjust switch Kcorrectly. See “Basic Adjustments“.
Fault: Dirt deposits have accumulated on the electrode rod.
Remedy: Remove compact system and clean electrode rod with a wet cloth.
Fault: The gasket of the electrode rod is damaged.
Measuring current at terminal
1 and 2 ≥ 20 mA. Fig. 13
Remedy: Replace compact system.