GESTRA NRS 1-2 User manual

1
NRS 12
Installation Instructions 81878003
Level Switch
NRS 12
GESTRA Steam Systems
EN
English

2
Contents
Usage for the intended purpose ..............................................................................................................4
Safety note .............................................................................................................................................4
Danger ...................................................................................................................................................4
LV (Low Voltage) Directive and EMC (Electromagnetic Compatibility) .......................................................4
ATEX (Atmosphère Explosible).................................................................................................................4
Note .......................................................................................................................................................4
Note on the Declaration of Conformity / Declaration by the Manufacturer ..........................................4
Important Notes
Page
Explanatory Notes
Scope of supply......................................................................................................................................5
Description .............................................................................................................................................5
Function .................................................................................................................................................5
Components ...........................................................................................................................................5
Design....................................................................................................................................................5
NRS 12................................................................................................................................................12
Attention...............................................................................................................................................12
Tools.....................................................................................................................................................12
Key.......................................................................................................................................................12
Examples of installation ........................................................................................................................13
Installation
Electrical Connection
NRS 12................................................................................................................................................14
Note .....................................................................................................................................................14
Tools.....................................................................................................................................................14
Wiring diagram.....................................................................................................................................15
NRS 12 .................................................................................................................................................6
Name plate / marking .............................................................................................................................7
Dimensions ............................................................................................................................................8
Technical Data
NRS 12..................................................................................................................................................9
Key.......................................................................................................................................................11
Design
NRS 12................................................................................................................................................10
Key.......................................................................................................................................................11
Functional Elements

3
Checking electrical connection .............................................................................................................16
Applying mains voltage ........................................................................................................................16
Contents – continued –
Commissioning
Page
Faultfinding list for troubleshooting ............................................................................................... 17, 18
Operational Malfunctions
Danger .................................................................................................................................................18
Disposal ...............................................................................................................................................18
Decommissioning
Limit switch MIN / MAX ........................................................................................................................16
Note .....................................................................................................................................................16
Performance Test

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Important Notes
Danger
The terminal strips of the NRS 12 are live during operation.
This presents the danger of electric shock!
Cut off power supply before attaching or detaching the housing lid and the terminal strips
of the equipment.
Usage for the intended purpose
Use level switch NRS 12 only in conjunction with GESTRA level electrodes NRG 164, NRG 1...52,
ER 50 and ER 56.
Safety note
The equipment must only be installed and commissioned by qualified and adequately trained per
sonnel.
Maintenance and retrofitting must only be performed by entrusted personnel who – through adequate
training – have achieved a recognised level of competence.
LV (Low Voltage) Directive and EMC (Electromagnetic Compatibility)
The equipment meets the requirements of the Low Voltage Directive 2006/95/EC and the EMC Directive
2004/108/EC.
ATEX (Atmosphere Explosible)
According to the European Directive 94/9/EC the equipment must not be used in potentially explosive
areas.
Note on the Declaration of Conformity / Declaration by the Manufacturer
For details on the conformity of our equipment according to the European Directives see our Declaration
of Conformity or our Declaration of Manufacturer.
The current Declaration of Conformity / Declaration of Manufacturer are available in the Internet under
www.gestra.de/documents or can be requested from us.
Note
The level electrodes NRG 164, NRG 1...52, ER 50 and ER 56 are simple items of
electrical equipment as defined in EN 6007911 section 5.7. 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 sepa
rate document.

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Scope of supply
NRS 12
1 Level switch NRS 12
1 Installation manual
Explanatory Notes
Description
Level switch for indicating one high and one low liquid level (MIN alarm, MAX alarm), designed for
use with GESTRA level electrodes NRG 164, NRG 1...52, ER 50 and ER 56. Application in steam and
(pressurised) hot water plants according to TRD 602 and TRD 604, sheet 1 and sheet 2.
Function
The level switch NRS 12 has one channel and is designed for signalling one MAX and one MIN alarm.
The level switch has a manual test function. The button “TEST LW” can simulate a malfunction in the
level electrode. As a precaution in case of a power failure the normally closed contacts will trigger an
alarm in the event of power failure. The level switch features the following four operating modes:
nNormal operation (no running dry, no high water)
nMIN alarm (running dry)
nMAX alarm (high water)
nAlarm (malfunction in level switch or level electrode)
Two red LEDs indicate low water (LW), high water (HW) or system error alarm.
Components
NRG 164
Level electrode NRG 164, PN 40
ER 50
Level electrode ER 50, NRG 1052, PN 6
ER 56
Level electrode ER 56, NRG 1652, PN 40
Design
NRS 12
Plugin unit in plastic case for installation in control cabinets. The terminals in the case are
accessible after loosening two screws and unplugging the unit from its base.
To avoid confusion with other plugin units of the GESTRA range, inserts are fitted in the bases so
that only the correct unit may be plugged into each base.
The plugin unit may be snapped onto a 35 mm supporting rail or screwed into position on a
mounting panel.

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NRS 12
Technical Data
Approval no.
TÜV · WR/WB · 08302
Note:
TÜV · WR/… for NRS 11, 12, 15,
TÜV…/WB… for NRS 13;
The type approval allows the combination of a water level controller and a water level limiter in
conjunction with the associated level electrodes.
Input
Three connections for two electrode rods and earth
Output
Two voltfree relay contacts,
contact rating 250 V, 500 W, 3 A resistive with a service life of 4 x 105switching cycles or
0.35 A inductive with 2 x 106switching cycles.
Contact material: silver, hardgold plated
Sensitivity of response (electrical conductivity of water at 25 °C)
> 0.5 ... < 1000 μS/cm or > 10 ... < 10000 μS/cm
Electrode voltage
11 V AC, free of direct voltage
Indicators and adjustors
1 LED for MAX alarm, 1 LED for MIN alarm, 1 button for simulating a MIN alarm
Supply voltage
24 V, 110 V, 120 V, 220 V, 240 V, 50 to 100 Hz (please indicate voltage when ordering).
When using the ancillary unit URN 1 the equipment can also be supplied with 24 V DC.
Power consumption
Approx. 3.5 VA
Protection
IP 40
Admissible ambient temperature
0 °C to 50 °C
Housing material
Base: Noryl SE 1GFN 2 UL 94 VO, black
Cover: RABS UL 94 VO, light grey
Weight
Approx. 0.8 kg

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Technical Data – continued –
Name plate / marking
Equipment designation
Fig. 1
Supply voltage
Sensitivity of response
NRS 1-2 b
GESTRA AG Bremen
230 V 50 Hz 3,5 VA
Mat.Nr.: 056390
0,5µS/cm IP 40
Betriebsanleitung beachten
See installation instructions
Voir instructions de montage

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

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Design
NRS 12
G
Fig. 6
GB C
F
E
D
Fig. 4 Fig. 5
NRS 1-2
MADE BY GESTRA
Test NW
MIN / NW
MAX / HW
A
A

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Functional Elements
NRS 12
NRS 1-2
MADE BY GESTRA
Test NW
MIN / NW
MAX / HW
Fig. 7
4
1
3
MAX 55°C
MAX 95%
%
IP 65

11
A Cover screws
B Base
C Upper part
D Mounting clip
E Cable entry (soft seal)
F Cable entry (marked in housing)
G Fixing hole d = 4.3 mm
1 Red LED for MAX alarm
2 Red LED for MIN alarm
3 Button “TEST LW” for simulating a MIN alarm
Design / Functional Elements
Key

12
Tools
nScrewdriver (5.5/100)
Attention
nTo provide sufficient ventilation, ensure a minimum spacing of 20 mm between
adjacent units.
Installation
NRS 12
On supporting rail (with mounting clip)
1. Clip level switch onto supporting rail.
2. Loosen cover screws Aand detach cover Cfrom its base B.
3. Select cable entry Eand remove corresponding seal.
On mounting panel
1. Loosen cover screws Aand unplug cover Cfrom its base B.
2. Unscrew mounting clip D.
3. Drill the hole Gmarked in the base to ∅4.3 mm.
4. Select cable entry E/ Fand remove corresponding seal.
5. Fasten base with two screws M4 onto mounting panel.
A Cover screws
B Base
C Cover
D Mounting clip
E Cable entry (soft seal)
F Cable entry (marked in housing)
G Hole d = 4.3 mm
H Supporting rail 35 x 15 mm to DIN EN 50022
Key

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Installation – continued –
Examples of installation
MAX 55°C
MAX 95%
%
IP 65
NRS 1-2
MADE BY GESTRA
Test NW
MIN / NW
MAX / HW
E
D B
E
H
F
F
C
A
Fig. 9
Fig. 8
G
G

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Electrical Connection
NRS 12
Cable required for wiring to the electrode: fourcore screened cable, e. g. IY(St)Y 2 x 2 x 0.8 or
LIYCY 4 x 0.52.
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 inverter
URN 1 (24 V d. c.)
Tools
nScrewdriver for slotted screws, size 2.5, completely insulated according to VDE 06801.
Note
nIf the terminal for the lowlevel (MIN) alarm is not connected, provide terminals 11
and 12 with a wire bridge, as otherwise the LED MIN indicating low water level
would be permanently illuminated.
nConnect screen only to terminal 8 of the level switch.
nThe sensitivity is indicated on the name plate.
nThe rated supply 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 therefore be
provided with commercial arc suppressor RC combinations, e. g. 0.1 μF/100 Ω.

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Electrical Connection – continued –
Wiring diagram
Fig. 10
Fig. 11 * Wire link, please observe note on page 14!
MAX (HW)
Drawn position of contacts:
deenergized / alarm
MAX (HW)
MIN (LW)
NRG 1...52
(ER 5...)
Supply
voltage
MIN alarm MAX alarm

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Apply supply voltage to level switch NRS 12.
Commissioning
Check that the NRS 12 and the associated level electrode are wired in accordance with the wiring
diagram, Fig. 10, Fig. 11.
Checking electrical connection
Applying supply voltage
Performance Test
1. When the electrodes are connected but exposed, the LED “MIN” must be illuminated.
2. When the electrodes are submerged the LED “MAX” must be illuminated. When pressing button
“TEST” the LED “MIN” must also light up.
3. To simulate the condition “electrode submerged” short circuit the corresponding electrode terminal
with terminal 12.
4. The electrode is supplied with 11 V AC +/– 20 %. When the electrodes are exposed this voltage
can be measured between the electrode tips and the earth connection by using a highresistance
instrument (100 kΩ/V).
Limit switch MIN / MAX
Note
nFor troubleshooting consult section “Operational Malfunctions” on pages 17/18.

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Operational Malfunctions
Faultfinding list for troubleshooting
Level electrode submerged – Low level alarm
Fault: The level switch signals a low level (MIN) alarm before the water level in the steam boiler
has reached the low level (MIN) switchpoint.
Remedy: Check the length of the low level (MIN) electrode rod. Measure the conductivity of the pro
cess or boiler water and compare the readings with the specification on the level switch.
Make sure that the level switch and the electrode are wired in accordance with the wiring
diagram, Fig. 10, Fig. 11.
Fault: The water level is above the low level (MIN) switchpoint but the red LED 2is still
illuminated or goes out only after quite a while.
Remedy: Check if the protection tube is provided with a vent hole. If the electrode is installed in an
external measuring pot, check the position of the shutoff valves.
Fault: The red LED 2is illuminated but the water level is above the low level (MIN) switchpoint.
Remedy: A control channel in the level switch has failed. Replace the level switch.
Low water level – no alarm is raised
Fault: The water level has dropped below the low level (MIN) switchpoint but the red LED 2does
not light up.
Remedy: Check if the protection tube is provided with a vent hole. If the electrode is installed in an
external measuring pot, check the position of the shutoff valves.
Electrode exposed – highlevel alarm
Fault: The level switch indicates a highlevel (MAX) alarm before the level in the boiler has
reached the high level (MAX) mark.
Remedy: Check length of the highlevel (MAX) electrode tip. Make sure that the level switch and the
electrode are wired in accordance with wiring diagram, Fig. 10, Fig. 11.

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Disposal
Decommissioning
Remove the level switch and separate the waste materials in accordance with the material
specification.
Electronic components (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2 are live during operation.
This presents the danger of electric shock!
Cut off power supply before attaching or detaching the housing lid and the terminal strips
of the equipment.
Operational Malfunctions – continued –
If faults occur that are not listed above, please contact our Technical Services or agency in your country.
Fault: After lowering the water level below the highlevel (MAX) mark, the red LED 1is still
illuminated or goes out only after quite a while.
Remedy: Check whether a vent hole has been provided in the protection tube. If the electrode is fitted
in a measuring pot outside the boiler, check the position of shutoff valves.
Fault: The red LEDs 1is illuminated without the level having reached the highlevel (MAX) mark.
Remedy: A control channel in the level switch has failed. Replace the level switch.
High water level reached – no alarm is raised
Fault: The water level is above the high level (MAX) switchpoint but the red LED 1is not
illuminated.
Remedy: Check whether a vent hole has been provided in the protection tube. If the electrode is fitted
in a measuring pot outside the boiler, check the position of shutoff valves. Measure the
conductivity of the boiler water and compare the readings with the specification on the level
switch.
Faultfinding list for troubleshooting – continued –

19
For your notes

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81878003/052011cm (80822706)
·
GESTRA AG
·
Bremen
·
Printed in Germany
Agencies all over the world:
www.gestra.de
GESTRA AG
Münchener Straße 77
28215 Bremen
Germany
Telefon [phone]
Telefax [phone]
E-Mail [email protected]
Web www.gestra.de