GESTRA NRS 1-52 User manual

EN
English
Level Switch
NRS 1-52
Original Installation Instructions
819176-02

2NRS 1-52 - Installation Instructions - 819176-02
Contents
Page
Important Notes
Usage for the intended purpose...............................................................................................................4
Function..................................................................................................................................................4
Safety note..............................................................................................................................................4
Potentially explosive areas ......................................................................................................................5
Technical Data
NRS 1-52................................................................................................................................................6
Scope of supply .....................................................................................................................................7
In control cabinet: Mounting level switch
Dimensions NRS 1-5...............................................................................................................................8
Key .........................................................................................................................................................8
Installation in control cabinet...................................................................................................................8
Example name plate / marking................................................................................................................9
In control cabinet: Wiring level switch
Wiring diagram for level switch NRS 1-52 .............................................................................................10
Key .......................................................................................................................................................10
Connecting supply voltage ....................................................................................................................11
Connecting MIN/MAX output contact .....................................................................................................11
Connecting level electrode ....................................................................................................................11
Tools .....................................................................................................................................................11
In the plant: Wiring level electrode
Connecting several level electrodes.......................................................................................................12
Key .......................................................................................................................................................12
Connection of level electrode ................................................................................................................13
Factory settings
Commissioning procedure
Changing response sensitivity ...............................................................................................................14
Checking switchpoint and function........................................................................................................15

3
NRS 1-52 - Installation Instructions - 819176-02
Contents - continued -
Page
Operation, Alarm and Test
Indicators and adjustors ........................................................................................................................17
Further Notes
Action against high frequency interference............................................................................................18
Decommissioning / replacing the equipment.........................................................................................18
Disposal................................................................................................................................................18
Declaration of Conformity
Directives and Standards ...................................................................................................................19

4NRS 1-52 - Installation Instructions - 819176-02
Important Notes
Usage for the intended purpose
The level switch NRS 1-52 in conjunction with level electrodes NRG 1.-.. and ER 5. is used as limit
switch, for instance in steam boilers, (pressurized) hot-water installations as well as condensate and
feedwater tanks. The level switch detects and indicates a MIN and a MAX water level.
The level switch NRS 1-52 can be used in combination with the following level electrodes:
Level electrodes
NRG 10-52,
NRG 16-52
Electrode with
4 rods
NRG 16-36
Electrode with
4 rods
NRG 16-4
Electrode with
1 rod
ER 50
Electrode with
4 rods
ER 56
Electrode with
4 rods
The operation of the level switch NRS 1-52 is based on the conductive measuring principle using the
electrical conductivity of the water for signalling water level. The level switch is designed for different
electrical conductivities and for connecting two level electrodes.
The length of the associated electrode rod determines the MIN and MAX water level switchpoints.
The level switch detects that the MIN or MAX water level is reached when the corresponding electrode
rod is exposed or submerged. After the de-energizing delay has elapsed, the MIN or MAX output con-
tact is switched over. At the same time the MIN or MAX LED changes from green to red.
A MIN or MAX alarm can be simulated by pressing the button “Test”.
Function
Safety note
The equipment must only be installed, wired 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.
Danger
The terminal strips of the equipment are live during operation.
This presents the danger of electric shock!
Always cut off power supply to the equipment before mounting, removing or connect-
ing the terminal strips!
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
NRS 1-52 - Installation Instructions - 819176-02
Important Notes - continued -
Potentially explosive areas
The equipment must not be used in potentially explosive areas.
Note
The level electrodes NRG 10-52, NRG 16-52, NRG 16-36, NRG 16-4 and ER 5.-1 are simple
items of electrical equipment as specified in EN 60079-11 section 5.7.
The equipment must be equipped with approved Zener barriers if used in potentially explo-
sive areas. Applicable in Ex zones 1, 2 (1999/92/EC).
The equipment does not bear an Ex marking.

6NRS 1-52 - Installation Instructions - 819176-02
NRS 1-52
Supply voltage
24 VDC +/– 20 %
Fuse
external 0.5 A (semi-delay)
Power consumption
2 VA
Connection of level electrode
2 inputs for level electrode NRG 10-52, NRG 16-52, NRG 16-36, NRG 16-4 and ER 5.-1,
4 poles with screen
Electrode voltage
5 VSS
Response sensitivity (Electrical conductivity of water at 25 °C)
> 0.5 ... < 1000 μS/cm or > 10 ... < 10 000 μS/cm (switch-selectable)
Outputs
2 volt-free change-over contacts, 8 A 250 V AC / 30 V DC cos ϕ= 1.
De-energizing delay: 3 sec.
Provide inductive loads with RC combinations according to manufacturer’s specification to ensure
interference suppression.
Indicators and adjustors
1 pushbutton “Test” for simulating MIN / MAX alarm,
2 red/green LEDs for indicating operating mode and MIN / MAX alarm,
1 green LED indicating “Power ON”,
1 code switch with 4 poles for changing the sensivity
Housing
Housing material: base: polycarbonate, black; front: polycarbonate, grey
Conductor size: 1 x 4.0 mm² solid per wire or
1 x 2.5 mm2per stranded wire with sleeve to DIN 46228 or
2 x 1.4 mm2per stranded wire with sleeve to DIN 46228;
Terminal strips can be detached
Fixing of housing: Mounting clip on supporting rail TH 35, EN 60715
Electrical safety
Pollution degree 2 for installation in control cabinet with protection IP 54, completely insulated
Protection
Housing: IP 40 to EN 60529
Terminal strip: IP 20 to EN 60529
Weight
approx. 0.2 kg
Technical Data

7
NRS 1-52 - Installation Instructions - 819176-02
NRS 1-52 - continued -
Ambient temperature
when system is switched on: 0 ° .... 55 °C,
during operation: -10 ... 55 °C
Transport temperature
–20 ... +80 °C (< 100 hours), defrosting time of the de-energized equipment before it can be put into
operation: 24 hours.
Storage temperature
–20 ... +70 °C, defrosting time of the de-energized equipment before it can be put into operation:
24 hours.
Relative humidity
max. 95 %, no moisture condensation
Technical Data - continued -
Scope of supply
NRS 1-52
1 Level switch NRS 1-52
1 Installation manual

8NRS 1-52 - Installation Instructions - 819176-02
In control cabinet: Mounting level switch
Dimensions NRS 1-5..
Fig. 1
1Upper terminal strip
2Lower terminal strip
Key
Installation in control cabinet
The level switch NRS 1-52 is clipped onto the support rail 4type TH 35, EN 60715 in the control
cabinet. Fig. 1
3Housing
4Supporting rail type TH 35, EN 60715
2
74
1
4 3
46 120

9
NRS 1-52 - Installation Instructions - 819176-02
In control cabinet: Mounting level switch - continued -
Example name plate / marking
Fig. 2
The date of production is printed on the side of the equipment.
1Terminals 16 - 23
2Wiring diagram, terminals 16 - 23
3Function
4Type designation
5Protection
6Protection class
7Operating data
(max. ambient temperature)
8Relay protection
9Safety note
0Manufacturer
aMaterial number, serial number
bConformity mark
cDisposal note
dType approval
eSupply voltage
fPower consumption
gExternal fuse for voltage supply
hWiring diagram, terminals 1 - 8
iTerminals 1 - 8
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10 NRS 1-52 - Installation Instructions - 819176-02
In control cabinet: Wiring level switch
Wiring diagram for level switch NRS 1-52
(–) (+)
579
5Connection of supply voltage 24 V DC with fuse 0.5 A (semi-delay) provided on site
6Reference electrode or vessel used as functional earth
7MIN electrode rod
8MAX electrode rod
9Central earthing point (CEP) in control cabinet
0MAX output contact
aMIN output contact
Key
16 17 18 19 20 21 22 23
12345678
MIN MAX
+-
8
a0
M 0.5 A
(semi-delay) 6
Fig. 3

11
NRS 1-52 - Installation Instructions - 819176-02
In control cabinet: Wiring level switch - continued -
Connecting supply voltage
The equipment is supplied with 24 V DC and fused with an external semi-delay fuse 0.5 A.
Please use a power supply unit with safe electrical isolation.
The power supply unit must be electrically isolated from dangerous contact voltages and must meet at
least the requirements on double or reinforced isolation according to one of the following standards:
EN 61010-1, EN 60730-1, EN 60950-1 or EN 62368-1.
Connecting level electrode
To connect the level electrode(s) use screened multi-core control cable with a min. conductor size
0.5 mm2, e. g. LiYCY 3 x 0.5 mm2 , max. length: 100 m.
Wire terminal strip in accordance with the wiring diagram. Fig. 3.
Connect the screen only once to the central earthing point (CEP) in the control cabinet.
Make sure that connecting cables leading to the level electrodes are segregated and run separately
from power cables.
Tools
nFor all functions: Screwdriver 0.8 x 4.0 or 0.8 x 4.5.
Connecting MIN/MAX output contact
Wire the upper terminal strip 1(terminals 16-18, 21-23) according to the desired switching functions.
Provide an external slow-blow fuse 2.5 A for the output contacts.
When switching off inductive loads, voltage spikes are produced that may impair the opera-
tion of control and measuring systems. Connected inductive loads must be provided with suppres-
sors such as RC combinations as specified by the manufacturer.
Attention
nDo not use unused terminals as support point terminals.

12 NRS 1-52 - Installation Instructions - 819176-02
12345678
ER 5...
54
3
2
123456 78
ER5.
32
1
12345678
NRG 16-36
8
5
12345678
NRG 16-52
43
2
1c
e
Fig. 4 Fig. 5
Fig. 6 Fig. 7
Fig. 8
In the plant: Wiring level electrode
Connecting several level electrodes
bLevel electrode NRG 10-52,
NRG 16-52, five pole connector
cLevel electrode NRG 16-36
dLevel electrode ER 5.., 4 pole connector
Key
eLevel electrode ER 5.., 6 pole connector
fLevel electrode NRG 16-4
gCentral earthing point (CEP) in
control cabinet
b
d
123456 78
NRG16-4
NRG16-4
3
3f
MAX
MIN
MAX
MAX MAX
MIN
MAX
MIN
gg
g g
g
NRG 1.-52
NRS 1-52 NRS 1-52
NRS 1-52NRS 1-52
NRS 1-52
MIN

13
NRS 1-52 - Installation Instructions - 819176-02
In the plant: Wiring level electrode - continued -
Connection of level electrode
The level switch NRS 1-52 can be used in combination with the following level electrodes:
Level electrodes
NRG 10-52,
NRG 16-52
Electrode with 4
rods
NRG 16-36
Electrode with 4
rods
NRG 16-4
Electrode with
1 rod
ER 50
Electrode with 4
rods
ER 56
Electrode with 4
rods
To connect the level electrode(s) use screened multi-core control cable with a min. conductor size
0.5 mm2, e. g. LiYCY 3 x 0.5 mm2 , max. length: 100 m.
Wire terminal strip in accordance with the examples Fig. 4 to 8.
Check the connection of the screen to the central earthing point (CEP) in the control cabinet.
Attention
nPlease observe the instructions given in the installation & operating manual for the
NRG 10-52, NRG 16-52, NRG 16-36, NRG 16-4 and ER 5.-1!
nMake sure that connecting cables leading to the level electrodes are segregated and
run separately from power cables.
Factory settings
Level switch NRS 1-52
The level switch features the following factory set default values:
nResponse sensitivity: 10 μS/cm (at 25 °C)

14 NRS 1-52 - Installation Instructions - 819176-02
Danger
The terminal strips of the equipment are live during operation.
This presents the danger of electric shock!
Always cut off power supply to the equipment before mounting, removing or connecting
the terminal strips!
Changing response sensitivity
If the electrical conductivity of water is < 10 μS/cm at 25°C change the response sensitivity to 0.5 µS/
cm as follows:
nCut off supply voltage.
nRemove lower terminal strip. Fig. 9
nInsert a screwdriver to the right and left between the terminal strip and the front frame.
nUnlock terminal strip on the left and right side. For this purpose move screwdriver in direction
of the arrow .
nRemove the terminal strip.
n Set switch S4 of code switch hto ON (= response sensitivity 0.5 µS/cm).
nRe-attach lower terminal strip.
nApply supply voltage. Equipment is restarted.
Commissioning procedure
Fig. 9
Fig. 10
h
h
Toggle switch, white
13
ON 24
Attention
Do not change the code switch hsettings of S1, S2 and S3!

15
NRS 1-52 - Installation Instructions - 819176-02
Commissioning - continued -
Checking switchpoint and function
Start
Activity Display Function
Switch on supply voltage.
Water level between MIN and
MAX.
LED “Power” is illuminated
MIN LED illuminated green MIN electrode rod immersed.
MAX LED illuminated green MAX electrode rod exposed.
Checking switchpoint and function
Lower water level until it is
below MIN level. MIN electrode
rod is exposed.
MIN LED flashes red. De-energizing delay is running.
MIN LED illuminated red Time delay elapsed, MIN output contact 16/18
closed, 17/18 open.
Fill vessel until MAX level is
exceeded. MAX electrode rod
enters the water.
MAX LED flashes red De-energizing delay is running.
MAX LED illuminated red Time delay elapsed, MAX output contact 21/23
closed, 22/23 open.
Possible installation faults
Status and indication Error Remedy
Water level below MIN
switchpoint, MIN LED
illuminated green.
MIN electrode rod is too long. Cut electrode rod according to MIN switchpoint.
If installed inside the boiler:
Upper vent hole in protec-
tion tube does not exist or is
obstructed.
Check installation of level electrode. Make sure
that the level in the protection tube corresponds
to the actual water level.
Water level between MIN and
MAX. MIN LED illuminated red
MIN electrode rod is too short. Replace level electrode and cut electrode rod(s)
to the length dictated by MIN switchpoint.
The earth connection to the
vessel is interrupted.
Clean seating surfaces and screw in level elec-
trode with metallic joint ring. Do not insulate
the electrode with hemp or PTFE tape!
Electrical conductivity of the
boiler water too low. Change response sensitivity to 0.5 μS/cm
Upper vent hole flooded.
Check installation of level electrode. Make sure
that the level in the protection tube corresponds
to the actual water level.
TEST button
MAX LED red/green
Fig. 11
MIN LED red/green
LED “Power”

16 NRS 1-52 - Installation Instructions - 819176-02
Possible installation faults
Status and indication Error Remedy
Water level above MAX
switchpoint, MAX LED
illuminated green.
MAX electrode rod is too short. Replace level electrode and cut electrode rod(s)
to the length dictated by MAX switchpoint.
The earth connection to the
vessel is interrupted.
Clean seating surfaces and screw in level elec-
trode with metallic joint ring. Do not insulate
the electrode with hemp or PTFE tape!
Electrical conductivity of the
boiler water is too low. Change response sensitivity to 0.5 μS/cm
If installed inside the boiler:
Upper vent hole in protec-
tion tube does not exist or is
obstructed.
Check installation of level electrode. Make sure
that the level in the protection tube corresponds
to the actual water level.
Water level between MIN and
MAX. MAX LED illuminated red.
MAX electrode rod is too long. Cut electrode rod according to MAX switch-
point.
Upper vent hole flooded.
Check installation of level electrode. Make sure
that the level in the protection tube corresponds
to the actual water level.
Water level between MIN and
MAX. MIN and MAX LEDs are
flashing simultaneously.
MAX electrode rod is longer than
MIN electrode rod.
Check and change the electrical connection of
the level electrode.
Commissioning - continued -
Checking switchpoint and function - continued -
Fig. 11
TEST button
MAX LED red/green
MIN LED red/green
LED “Power”

17
NRS 1-52 - Installation Instructions - 819176-02
Operation
Status Display Function
Water level between MIN and
MAX.
MIN and MAX LEDs illuminated
green.
MIN output contact 16/18 open, 17/18 closed.
MAX output contact 21/23 open, 22/23 closed.
MIN alarm
Water level below MIN
switchpoint.
MIN LED flashes red. De-energizing delay is running.
MIN LED illuminated red Time delay elapsed, MIN output contact 16/18
closed, 17/18 open.
MAX alarm
Water level above MAX
switchpoint.
MAX LED flashes red. De-energizing delay is running.
MAX LED illuminated red Time delay elapsed, MAX output contact 21/23
closed, 22/23 open.
Operation, Alarm and Test
Indicators and adjustors
Testing MIN alarm and MAX alarm
During operation:
Water level between MIN
and MAX.
Press and hold down button
“Test”.
MAX LED flashes red. De-energizing delay is running.
MAX LED is illuminated red for
3 sec. MAX output contact 21/23 closed, 22/23 open.
MIN and MAX LEDs illuminated
green for 1 sec.
MAX output contact 21/23 open, 22/23 closed.
MIN output contact 16/18 open,
17/18 closed.
MIN LED flashes red. De-energizing delay is running.
MIN LED is illuminated red for
3 sec.
MIN output contact 16/18 closed,
17/18 open.
The test is finished. Release
button “Test”. Equipment
returns to operating mode.
Note: If you continue to hold down the Test button, a new test is started.
You can abort the test any moment by releasing the Test button.

18 NRS 1-52 - Installation Instructions - 819176-02
Action against high frequency interference
High-frequency interference can be caused by out-of-phase switching operations. Should sporadic
failures or malfunctions occur take the following remedial actions in order to suppress interference:
nProvide inductive loads with RC combinations according to manufacturer's specification to ensure
interference suppression.
nIncrease the distance to sources of interference.
nCheck the connection of the screen to the central earthing point (CEP) in the control cabinet.
nHF interference suppression by means of hinged-shell ferrite rings.
nMake sure that connecting cables leading to the level electrodes are segregated and run separately
from power cables.
Further Notes
nSwitch off supply voltage and cut off power supply to the equipment.
nRemove the lower and upper terminal strips. Fig. 9.
nRelease the white fixing slide at the bottom of the equipment and take the equipment off the
supporting rail.
Decommissioning / replacing the equipment
Disposal
For the disposal of the equipment observe the pertinent legal regulations concerning waste disposal.
If faults occur that are not listed above or cannot be corrected, please contact our service centre or
authorized agency in your country.

19
NRS 1-52 - Installation Instructions - 819176-02
For more information on the conformity of the equipment as well as applied Directives and Standards
please refer to our Declaration of Conformity and associated certificates and/or approvals.
The Declaration of Conformity can be found online at www.gestra.com and associated certificates can
be requested from:
GESTRA AG
Münchener Straße 77
28215 Bremen
Germany
Telefon [phone]
Telefax [phone]
E-mail [email protected]
Web www.gestra.com
Note that Declarations of Conformity and associated certificates lose their validity if equipment is
modified without prior consultation with us.
Declaration of Conformity
Directives and Standards

819176-02/07-2022cm[uk] (808832-02) · GESTRA AG · Bremen · Printed in Germany
GESTRA AG
Münchener Straße 77
28215 Bremen
Germany
Telefon [phone]
Telefax [phone]
E-mail [email protected]
Web www.gestra.com
Agencies all over the world: www.gestra.com
UK Importer:
GESTRA UK Ltd
Unit 1 Sopwith Park, Royce Close,
West Portway Business Park, Andover,
Hampshire SP10 3TS
United Kingdom