GESTRA NRS 1-8 User manual

1
NRS 1-8
Installation Instructions 818612-03
Level Switch NRS 1-8
GESTRA Steam Systems
EN
English

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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......................................................................................................................................4
Description .............................................................................................................................................4
Function .................................................................................................................................................5
System components ...............................................................................................................................5
Design....................................................................................................................................................5
NRS 1-8................................................................................................................................................12
Attention...............................................................................................................................................12
Tools.....................................................................................................................................................12
Key.......................................................................................................................................................12
Examples of installation ........................................................................................................................13
Installation
Electrical Connection
NRS 1-8................................................................................................................................................14
Voltage table.........................................................................................................................................14
Attention...............................................................................................................................................14
Notice...................................................................................................................................................14
Tools.....................................................................................................................................................14
Wiring diagram.....................................................................................................................................15
NRS 1-8..................................................................................................................................................6
Corrosion resistance...............................................................................................................................7
Name plate/marking ............................................................................................................................... 7
Dimensions.............................................................................................................................................8
Technical Data
NRS 1-8..................................................................................................................................................9
Key.......................................................................................................................................................11
Component Parts
NRS 1-8................................................................................................................................................10
Key.......................................................................................................................................................11
Functional Elements

3
Checking electrical connection .............................................................................................................16
Applying mains voltage.........................................................................................................................16
Contents – continued –
Commissioning
Page
Water level limiter.................................................................................................................................17
Notice...................................................................................................................................................17
Operation
Fault finding list for troubleshooting................................................................................................ 17, 18
Operational Malfunctions
Danger .................................................................................................................................................18
Disposal................................................................................................................................................18
Decommissioning
Water level limiter.................................................................................................................................16
Performance Test
Declaration of Conformity .....................................................................................................................19
Annex

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Important Notes
Danger
The terminal strips of the NRS 1-8 are live during operation.
This presents the danger of electric shock!
Cut off power supply before mounting or removing the terminal strips and the
housing cover.
Usage for the intended purpose
Use level switch NRS 1-8 only in conjunction with level electrodes NRG 16-12, NRG 17-12,
NRG 19-12 for water level limiting (high level alarm).
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.
Explanatory Notes
Scope of supply
NRS 1-8
1 Level switch NRS 1-8
1 Installation manual
Description
Self-monitoring high-level alarm with periodic self-checking routine, designed for use in conjunction
with level electrodes NRG 16-12, PN 40, NRG 17-12, PN 63, NRG 19-12, PN 160.
The equipment combination detects the MAX water level (high level limiter). Application in steam and
pressurised hot water plants in accordance with TRD 602, sheet 1 and sheet 2 as well as EN 12952
and 12953.
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 94/9/EC the equipment must be equipped with approved Zener
barriers if used in potentially explosive areas. 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 item of
equipment without its specific name plate must neither be commissioned nor operated.

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Explanantory Notes – continued –
Function
The level switch NRS 1-8 is a two-channel unit provided with an automatic self-checking circuitry in
accordance with DIN VDE 0116, prEN 50156. The self-checking is effected periodically. During the
test the cable between electrode and level switch and the self-checking circuitry (redundancy) are
checked.
The output relays are not influenced by the internal tests.
The level switch can also be tested manually by pushing the button “TEST 1” to simulate a mal-
function in the level electrode.
The toggle switch “TEST 2 / INSPECTION” is designed for testing the function of the self-checking
routine by simulating a malfunction. The contact relays are of the normally closed type and will
automatically signal alarm condition in the event of a malfunction. The level switch can signal the
following three operating conditions:
nNormal operation (correct water level in boiler)
nAlarm (level in boiler too high)
nAlarm (malfunction in level switch or level electrode)
A green LED indicates power supply. Two red LEDs signal an alarm in the event of high water level or
system malfunction.
The failure of one channel (loss of redundancy) is signalled by one red LED.
The equipment combination of electrode NRG 16-12, NRG 17-12 or NRG 19-12 and level switch
NRS 1-8 provides fail-safe protection against a first fault, i. e. the system will still continue to provide
the safety function even after the occurrence of a first fault.
System components
NRG 16-12
Level electrode NRG 16-12, PN 40
NRG 17-12
Level electrode NRG 17-12, PN 63
NRG 19-12
Level electrode NRG 19-12, PN 160
Design
NRS 1-8
Plug-in unit in plastic case for installation in control cabinets. Remove cover to access the terminals
in the housing base. Thanks to the code plug the equipment cannot be connected inadvertently to
wrong GESTRA equipment. The equipment may be snapped onto a 35 mm supporting rail or screwed
into position on a mounting panel.

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NRS 1-8
Technical Data
TÜV approval
TÜV · HWS · 08-417
Input
Four terminals for one level electrode
NRG 16-12, PN 40
NRG 17-12, PN 63
NRG 19-12, PN 160
Output
Two volt-free relay contacts
Max. contact rating: 250 V, 300 W, 3 A resistive with a life of 5 x 105switching cycles
or 0.35 A inductive with a life of 2 x 106switching cycles. Contact material: silver, hard-gold plated.
Delay of response
Default factory setting: 3 sec.
Up to 25 sec. after prior consultation with TÜV.
Sensitivity of response
10 µS/cm at 25 °C when used in conjunction with level electrode without measuring surface extension
and cell constant 0.3.
0.5 µS/cm at 25 °C when used in conjunction with level electrode with measuring surface extension and
cell constant 0.13 (see data sheet NRG 16-12).
Indicators and adjustors
Two LEDs for “Alarm”, one LED for “Power”, one button “TEST 1”,
one toggle switch “TEST 2 / INSPECTION”.
Mains voltage
230 V +/– 10 %, 50/60 Hz (please state voltage when ordering).
Special voltage 115 V +/– 10 %, 50/60 Hz or 24 V+/– 10 %, 50/60 Hz.
When using the ancillary unit URN 1 the equipment can also be fed with 24 V DC.
Power consumption
5 VA
Protection
NRS 1-8 IP 40 to EN 60529
Admissible ambient temperature
0 °C to 55 °C
Case materials
Base: Noryl SE 1-GFN 2 UL 94 VO, black
Cover: R-ABS UL 94 VO, stone grey
Weight
approx. 0.6 kg

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Corrosion resistance
If the equipment is used for the intended purpose, its safety is not impaired by corrosion.
Technical Data – continued –
Name plate/marking
Equipment designation
Fig. 1
Mains voltage
Sensitivity of response
Delay of response
External fuse

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Technical Data – continued –
Dimensions
Fig. 2
106 7
32
51
Fig. 3
112
85

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Component Parts
72 3
6
5
4
Fig. 4 Fig. 5
Fig. 6
1
NRS 1-8
1

10
Fig. 7
b
9
0
a
MAX 55°C
MAX 95%
%
IP 65
Functional Elements
NRS 1-8

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1Cover screws
2Base
3Upper part of housing
4Mounting clip
5Cable entry (flexible)
6Cable entry (housing)
7Fixing hole d = 4.3 mm
9Toggle switch “TEST 2 / INSPECTION” for internal self-checking
0Red LED “High level alarm”
aButton “TEST 1” for simulating a high level alarm
bGreen LED “Power”, indicating power supply
Component Parts / Functional Elements
Key

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Tools
nScrewdriver (5.5/100)
Attention
nTo provide sufficient ventilation, ensure a minimum spacing of 20 mm between adjacent
units.
Installation
NRS 1-8
On supporting rail (with mounting clip)
1. Clip level switch onto supporting rail.
2. Loosen cover screws 1and detach cover 3from base 2.
3. Select cable entry 5and remove corresponding seal.
On mounting panel
1. Loosen cover screws 1and detach cover 3from base 2.
2. Unscrew mounting clip 4.
3. Drill hole 7marked in the base to ∅4.3 mm.
4. Select cable entry 5/ 6and remove corresponding seal.
5. Fix base with two M4 screws onto mounting panel.
1Cover screws
2Base
3Upper part of housing
4Mounting clip
5Cable entry (flexible)
6Cable entry (housing)
7Fixing hole d = 4.3 mm
8Supporting rail TS 3 5x 15 DIN EN 50022
Key

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Installation – continued –
Fig. 8
42
5
8
6
6
3
1
Fig. 9
7
7
MAX 55°C
MAX 95%
%
IP 65
Examples of installation

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Electrical Connection
NRS 1-8
Cable required for wiring the electrode: four-core screened cable, e. g. I-Y(St)Y 2 x 2 x 0.8 or
LIYCY 4 x 0.5 mm2.
Max. cable length 100 m with a conductivity from 10 µS/cm.
Max. cable length 30 m with a conductivity from 0.5 µS/cm.
Max. cable length 15 m with a conductivity from 0.5 µS/cm when used in conjunction
with ancillary unit URN 1 (24 V DC).
Tools
nScrewdriver for slotted screws, size 2.5, completely insulated according to DIN VDE 0680-1
Voltage table
Use this voltage table as reference when checking the level electrode for malfunctions or submersion.
Please observe the wiring diagram for NRS 1-8. Fig. 10, Fig. 11
Attention
nTo protect the switching contacts provide circuit with a 2.5 A slow-blow fuse or
according to TRD regulations (1.0 A for 72 h operation).
nThe screen must not make any other electrical contact
Notice
nThe self-checking routine of the level switch NRS 1-8 reduces U1-2 all 40 seconds to
zero volt.
nConnect screen only to terminal 8 of the level switch.
nThe sensitivity of response is indicated on the name plate.
nThe rated voltage is indicated on the name plate.
nWhen switching off inductive loads, voltage spikes are produced that may impair the
operation of control and measuring systems. Inductive loads should be provided with
commercial arc suppressor RC combinations, e.g. 0.1 µF/100 W.
U1-2 U1-2
10 µS/cm 0.5 µS/cm
2 Veff
C=0.3 cm-1
10 Veff
C=0.13 cm-1

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Electrical Connection – continued –
Wiring diagram
Fig. 10
Fig. 11
This wiring diagram is only applicable for France!
Safety circuit
Safety circuit
L N
L N

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Apply mains voltage to level switch NRS 1-8.
Commissioning
Make sure that the NRS 1-8 and the associated level electrode are wired in accordance with the wiring
diagram. Fig. 10, Fig. 11
Checking electrical connection
Applying mains voltage
Performance test
1. Check length of electrode rod (see installation manual of level electrode).
2. When switching on the mains voltage the green LED bmust be permanently illuminated. Fig. 7
3. Completely open valves of water-level gauge glass on steam boiler.
4. Fill up with feedwater until the max. water level (high level mark) is exceeded.
The two red LEDs 0of the level switch must light up after the response delay.
If the automatic self-testing routine is activated at this point in time an alarm will only be raised after
twice the response delay time has elapsed.
5. To simulate a high level alarm when the electrode tip is exposed press button “TEST 1” a. Press
and hold down the button until the response delay has elapsed. Both red LEDs 0must then light up.
6. To test the self-checking circuitry of the level switch proceed as follows:
When the electrode tip is exposed set toggle switch “TEST 2 / INSPECTION” 9to the direction of
the arrow.
After max. two minutes the two red LEDs 0should signal a low-level alarm. Note that the button
“TEST 1” amust not be operated during this test nor must the level fall below the low level mark.
After a successful test set switch 9 back to its original position.
Both red LEDs 0must extinguish after the response delay.
Water level limiter

17
Operational malfunctions
Fault finding list for troubleshooting
Level electrode exposed - High-level alarm
Fault: The level switch raises a high-level alarm before the level in the boiler has reached
the high-level mark.
Remedy: Check length of high-level electrode tip. Make sure that the level switch and the
electrode are wired in accordance with the wiring diagram.
Fault: After lowering the water level below the high-level mark, the two red LEDs 0are
still illuminated or go out only after quite some time.
Remedy: Check whether the protection tube is provided with a vent hole.
If the electrode is fitted in a measuring pot outside the boiler, check positions
of isolating valves.
Fault: One or both LEDs 0light up without the water level having reached the high-level
mark.
Remedy: This means loss of redundancy in the level switch, i. e. failure of one or two of the
channels. Replace level switch.
High water level reached - no function
Fault: The water level exceeds the high-level mark but neither of the two red LEDs 0
lights up.
Remedy: Check whether the protection tube is provided with a vent hole.
If the electrode is fitted in a measuring pot outside the boiler, check positions
of isolating valves. Measure the conductivity of the boiler water and compare the
value obtained with the specification on the name plate.
Fault: The test “TEST 2 / INSPECTION” 9was not successful, i. e. only one red LED 0or
none of the two lit up after max. two minutes .
Remedy: Replace level switch.
Operation
Use in conjunction with level switch NRG 1...-12 in steam and pressurised hot water plants in accord-
ance with TRD 401, TRD 602, TRD 604, EN 12952, EN 12953 or according to other national regulations.
Water level limiter
Notice
nTo analyse and eliminate malfunctions refer to section
“Fault finding list for troubleshooting” on pages 17 – 18.

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Disposal
Decommissioning
Remove the level switch and separate the waste materials in accordance with the material specification.
Electronic components (circuit boards) must be disposed of separately.
For the disposal of the level switch observe the pertinent legal regulations concerning waste disposal.
Danger
The terminal strips of the NRS 1-8 are live during operation.
This presents the danger of electric shock!
Cut off power supply before mounting or removing the terminal strips and the housing
cover.
Operational Malfunctions – continued –
If faults occur that are not listed above or cannot be corrected, please contact our service centre or
authorized agency in your country.

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Declaration of Conformity
Annex
We hereby declare that the equipment NRS 1-8 conforms to the following European guidelines:
nLow Voltage Directive 73/23/eec version 93/68/eec
nEMC Directive 89/336/eec version 93/68/eec
nLow Voltage Standard EN 50178
nEMC Standard EN 50081-2, EN 50082-2
This declaration is no longer valid if modifications are made to the equipment without consultation
with us.
Quality Assurance Manager
Lars Bohl
(Academically qualified engineer)
Head of the Design Dept.
Uwe Bledschun
(Academically qualified engineer)
Bremen, 03
rd January 2005
GESTRA AG

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818612-03/09-2009cm (803967-08) · GESTRA AG · Bremen · Printed in Germany
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