GESTRA NRS 1-50 Series User manual

1
NRS 1-50
For ONE Electrode
Installation Instructions 818987-05
Level Switch NRS 1-50
GESTRA Steam Systems
EN
English

2
Contents
Usage for the intended purpose ..............................................................................................................4
Function .................................................................................................................................................4
Application
Page
Directives and Standards
Pressure Equipment Directive (PED) 2014/68/EU ....................................................................................5
Functional Safety acc. to IEC 61508........................................................................................................5
VdTÜV Bulletin “Wasserstand 100” (= Water Level 100)..........................................................................5
Approvals for Marine Applications...........................................................................................................5
LV (Low Voltage) Directive and EMC (Electromagnetic Compatibility) .......................................................5
Note on the Declaration of Conformity / Declaration by the Manufacturer .........................................5
ATEX (Atmosphère Explosible).................................................................................................................6
UL/cUL (CSA) Approval............................................................................................................................6
Safety characteristics of the subsystem NRG 1...-50 / NRS 1-50.............................................................7
Terms and abbreviations.........................................................................................................................7
Determination of the Safety Integrity Level (SIL) for safety-related systems.............................................8
Functional Safety acc. to IEC 61508
NRS 1-50..............................................................................................................................................12
Dimensions and Functional Elements
Safety note ...........................................................................................................................................13
Scope of supply....................................................................................................................................13
Important Notes
NRS 1-50........................................................................................................................................9 – 10
Name plate / marking ...........................................................................................................................11
Technical Data
Mounting level switch NRS 1-50...........................................................................................................14
Installation

3
Contents - continued -
Checking switchpoint and function .......................................................................................................20
Commissioning Procedure
Page
Indicators and adjustors........................................................................................................................21
Operation, Alarm and Test
Indication, diagnosis and remedy..................................................................................................21 – 22
Troubleshooting
Electrical Connection
Supply voltage......................................................................................................................................14
Connection of level electrode................................................................................................................14
Connection of safety circuit...................................................................................................................14
Connection of logic unit (standby input).................................................................................................14
Connection for signal output .................................................................................................................15
Tools.....................................................................................................................................................15
Wiring diagram for level switch NRS 1-50.............................................................................................16
Schematic representations of arrangements.........................................................................................17
Explanatory notes to schematic respresentations..................................................................................18
Factory setting......................................................................................................................................19
Basic Settings
Measuring voltage across level switch..................................................................................................23
Checking level electrode
Action against high frequency interference ...........................................................................................24
Interlock and interlock deactivation.......................................................................................................24
Checking the switchpoints....................................................................................................................24
Decommissioning / replacing level switch.............................................................................................24
Disposal................................................................................................................................................24
Further Notes

4
Application
Usage for the intended purpose
The level switch NRS 1-50 is used in conjunction with level electrode NRG 1...-.. to limit the water level
in steam boilers and (pressurised) hot-water plants.
Water level limiters switch off the heating when the water level falls below the set minimum level (low
water).
Depending on the specified directives or standards, the level switch NRS 1-50 is intended to be used in
combination with the following level electrodes:
Level electrode NRG 1...-..
PED Pressure Equipment
Directive 2014/68/EU +
Functional Safety IEC 61508
SIL 3
NRG 16-50 NRG 17-50 NRG 19-50 NRG 111-50 NRG 16-36
VdTÜV Bulletin “Wasserstand
100” (= Water Level 100)
NRG 16-50
NRG 16-11
NRG 17-50
NRG 17-11
NRG 19-50
NRG 19-11
NRG 111-50
NRG 111-11 NRG 16-36
Marine applications
GL/LR Directives NRG 16-50S NRG 16-11S NRG 16-38S NRG 16-39S
Function
The level switch NRS 1-50 is designed for different electrical conductivities of the boiler water and for
connecting one level electrode.
When the water level falls below the low level the level electrode is exposed and a low level alarm is
triggered in the level switch. This switchpoint is determined by the length of the electrode rod (level
electrode NRG 1...-50, NRG 1...-11, NRG 16-36).
After the de-energizing delay has elapsed, the two output contacts of the level switch will open the
safety circuit for the heating. The switching-off of the heating is interlocked in the external safety
circuit and can only be deactivated when the level electrode enters the water again.
In addition the signalling contact for external signalling devices closes instantaneously.
An alarm will also be raised if a malfunction occurs in the level electrode and/or the electrical
connection.
If the level electrode is installed in an isolatable level pot outside the boiler, make sure that the con-
necting lines are rinsed regularly. During the rinsing process the water level cannot be measured in
the level pot for 5 minutes. The level switch therefore bypasses the level electrode and monitors the
rinsing and bypass time (standby input, controlled by the logic unit SRL 6-50).
If the connecting lines for steam ≥ 40 mm and water ≥ 100 mm, the installation is considered to be
internal. In this case the rinsing processes do not have to be monitored.
An automatic self-testing routine monitors the safety functions in the level switch and the level elec-
trode. In the event of a malfunction the safety circuit opens instantaneously and switches the heating
off.
Alarm and error messages are indicated by LEDs and an alarm can be simulated by pressing the test
button.

5
Directives and Standards
Pressure Equipment Directive (PED) 2014/68/EU
Water level limiters are safety accessories as defined in the Pressure Equipment Directive (PED).
The level switch NRS 1-50 in conjunction with level electrode NRG 1...-50 and NRG 16-36 is EC type
approved according to EN 12952/EN 12953. These Directives state, among other things, the require-
ments made on limiting systems and equipment for steam boiler plants and (pressurised) hot-water
installations.
VdTÜV Bulletin “Wasserstand 100” (= Water Level 100)
The level switch NRS 1-50 in conjunction with the level electrodes NRG 1...-50, NRG 1...-11 and NRG
16-36 is type approved according to the VdTÜV Bulletin “Water Level 100”.
The VdTÜV Bulletin “Wasserstand (= Water Level) 100” specifies the requirements made on water level
control and limiting equipment for boilers.
Functional Safety acc. to IEC 61508
The level switch NRS 1-50 is certified acc. to IEC 61508 only if used in combination with level elec-
trode NRG 1...-50 / NRG 16-36 . This standard describes the functional safety of safety-related electri-
cal/electronic/programmable electronic systems.
The equipment combination NRG 1...-50 or NRG 16-36 + NRS 1-50 corresponds to a type B subsys-
tem with Safety Integrity Level (SIL) 3.
Approvals for Marine Applications
The level switch NRS 1-50 in conjunction with level electrodes NRG 16-50S/NRG 16-11S/NRG 16-38S
and NRG 16-39S is approved for marine applications. See data sheet NRG 16-50S, NRG 16-38S and
NRG 16-39S.
LV (Low Voltage) Directive and EMC (Electromagnetic Compatibility)
The level switch NRS 1-50 meets the requirements of the Low Voltage Directive 2014/35/EU and the
EMC Directive 2014/30/EU.
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 Declara-
tion of Conformity or our Declaration of Manufacturer.
The current Declaration of Conformity / Declaration of Manufacturer are available in the Internet under
www.gestra.en/documents or can be requested from us.

6
ATEX (Atmosphère Explosible)
According to the European Directive 2014/34/EU the level switch NRS 1-50 must not be used in
potentially explosive areas.
Note
The level electrodes NRG 1...-50, NRG 1...-11 and NRG 16-36 are simple items of electri-
cal equipment as specified in EN 60079-11 section 5.7. According to the European Direc-
tive 2014/34/EU 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.
Note that the requirements of the IEC 61508 are not met if the NRG 1...-50, NRG 1...-11
and NRG 16-36 + Zener barriers + NRS 1-50 are interconnected!
Directives and Standards - continued -
UL/cUL (CSA) Approval
The equipment meets the requirements of Directives: UL 508 and CSA C22.2 No. 14-13, Standards for
Industrial Control Equipment. File E243189.

7
Functional Safety acc. to IEC 61508
Safety characteristics of the subsystem NRG 1...-50 / NRS 1-50
The level switch NRS 1-50 is certified acc. to IEC 61508 if used in combination with level electrode NRG
1...-50 / NRG 16-36.
The combination NRG 1...-50 / NRG 16-36 / NRS 1-50 corresponds to a type B subsystem with Safety
Integrity Level (SIL) 3. Type B means that the behaviour under fault conditions of the used components
cannot be completely determined. The functional safety of the equipment combination refers to the de-
tection and evaluation of the water level and, as a consequence, the contact position of the output relays.
The design of the equipment combination NRG 1...-50 / NRG 16-36 / NRS 1-50 corresponds to the ar-
chitecture 1oo2.
This architecture consists of two channels that detect and diagnose faults in each other. If a fault is de-
tected, the equipment combination NRG 1...-50 / NRG 16-36 / NRS 1-50 will go to the safe state, which
means that the contacts of both output relays will open the safety circuit.
Safety characteristics SIL Architecture Lifetime
(a)
Proof Test
Interval (a)
General 3 1oo2 20 20
SFF PFDav PFHav λDU
Level switch NRS 1-50 alone 98.54 % 1.18 x 10-4 3.73 x 10-8 7.33 x 10-8 /h
Level switch NRS 1-50 in conjunction with
one level electrode NRG 1...-50, NRG 16-36 98.17 % 1.69 x 10-4 4.54 x 10-8 9.33 x 10-8 /h
Fig. 1
Terms and abbreviations
Terms
Abbreviations Description
Safety Integrity Level
SIL Classification of the Safety Integrity Level acc. to IEC 61508
Lifetime (a) Functional safety: Lifetime in years
Safe Failure Fraction
SFF
Percentage of failures without the potential to put the safety-related system into
a dangerous state
Probability Failure per Demand
(Low Demand) PFDav Average probability of failure on demand for low demand mode (once a year)
Probability Failure per Hour
PFHav Probability of failure per hour
λDU Failure rate for all dangerous undetected failures (per hour) of a channel of a
subsystem
Fig. 2

8
Functional safety acc. to IEC 61508 - continued -
Determination of the Safety Integrity Level (SIL) for safety-related systems
Level electrode, level switch and actuators (auxiliary contactor in safety circuit) are subsystems and
together constitute a safety-related system that executes a safety function.
The specification of the safety-related characteristics Fig. 1 refers to the level electrode and the level
switch including the output contacts. The actuator (e. g. an auxiliary contactor in the safety circuit) is
installation specific and, according to IEC 61508, must be considered separately for the whole safety-
related system.
Table Fig. 3 shows the dependence of the Safety Integrity Level (SIL) on the average probability of failure
on demand of a safety function for the whole safety-related system (PFDsys). The “Low demand mode”
is here considered for a water level limiter, which means that the frequency of demands for operation of
the safety-related system is no greater than one per year.
Low demand mode PFDsys Safety Integrity Level
(SIL)
≥ 10 -5 ... < 10 -4 4
≥ 10 -4 ... < 10 -3 3
≥ 10 -3 ... < 10 -2 2
≥ 10 -2 ... < 10 -1 1
Fig. 3
The table in Fig. 4 indicates the attainable Safety Integrity Level (SIL) as a function of the Safe Failure
Fraction (SFF) and the Hardware Fault Tolerance (HFT) for safety-related systems.
Hardware Fault Tolerance (HFT) for type B Safe Failure Fraction
(SFF)
012
SIL 1 SIL 2 < 60 %
SIL 1 SIL 2 SIL 3 60 % – < 90 %
SIL 2 SIL 3 SIL 4 90 % – < 99 %
SIL 3 SIL 4 SIL 4 ≥ 99 %
Fig. 4

9
NRS 1-50
Supply voltage
24 VDC + / – 20 %, 0.3 A;
100 – 240 VAC +10 / –15 %, 47 – 63 Hz, 0.2 A (optional)
External fuse
0.5 A (semi-delay)
Power consumption
7 VA
Response sensitivity (Electrical conductivity of water at 25 °C)
> 0,5 ... < 1000 µS/cm or
> 10 ... < 10000 µS/cm
Connection of level electrode
1 input for level electrode NRG 1...-50, NRG 1...-11, NRG 16-36, 4 poles, with screen.
Stand-by input
1 volt-free input, 24 V DC, for monitoring the purging and bypass time.
Max. bypass time: 5 minutes.
Safety circuit
2 volt-free make contacts, 6 A 250 V AC / 30 V DC cos ϕ= 1.
Delay of response: 3 seconds, 15 sec. for marine applications.
Provide inductive loads with RC combinations according to manufacturer's specification to ensure
interference suppression.
Signal output
1 volt-free output for instantaneous external signalling, 24 VDC, max. 100 mA (semiconductor output).
Indicators and adjustors
2 buttons for test and diagnosis,
2 red/green LEDs for indicating the operating mode and alarm.
3 red LEDs for diagnosis.
Housing
Housing material: base: polycarbonate, black; front: polycarbonate, grey.
Conductor size: 1 x 4.0 mm2solid 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
Degree of contamination: 2, overvoltage category III to EN 61010-01.
Protection
Housing: IP 40 to EN 60529
Terminal strip: IP 20 to EN 60529
Weight
approx. 0.5 kg
Technical Data

10
NRS 1-50 - 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
Site altitude
max. 2000 m
Approvals
EC Prototype approval PED Pressure Equipment Directive 2014/68/EU
EN 12952-11, EN 12953-09: Requirements made on limiting
equipment for boilers
Functional safety IEC 61508: Functional safety of safety-related
SIL 3 electrical/electronic/programmable electronic systems
TÜV type approval VdTÜV Bulletin “Wasserstand 100” (= Water Level 100):
Requirements made on water level limiting & control equipment
Type approval no. TÜV.SWB.XX-422
(see nameplate)
Marine applications Regulations of various classification societies
Technical Data - continued -

11
Wasserstandbegrenzer
Water level limiter
Limiteur de niveau d’eau
Tamb = 55°C (131°F)
IP 40 (IP20)
7 VA
0525
250V
T 2,0A
TÜV . SWB . xx-422
GESTRA AG
Münchener Str. 77
D-28215 Bremen
Niveauschalter
Level switch
Commutateur de niveau
20
29
21
30
1. / 2.
3sec.
6
14
7
15
Funktionale Sicherheit
Functional safety
Sécurité fonctionnelle
IEC 61508
SIL 3
0,5 µS/cm
9
2
NRG 1...-50
1. / 2.
1
2
3
1345
10 11 12 13 16 17 23 24 26 27
NRS 1-50
100-240 V ~
-15 / +10%
MIN SRL
1. / 2.
+-
N
M 0,5A
L
+-
Alarm extern
24 VDC
100 mA
ZEP
Betriebsanleitung
beachten
See installation
instructions
Voir instructions de
montage
NRS 1-50
NRS 1-50
Alarm extern
24 VDC
100 mA
ZEP
Wasserstandbegrenzer
Water level limiter
Limiteur de niveau d’eau
Tamb = 55°C (131°F)
7 VA IP 40 (IP20)
Betriebsanleitung
beachten
See installation
instructions
Voir instructions de
montage
0525
250V
T 2,0A
TÜV . SWB . xx-422
GESTRA AG
Münchener Str. 77
D-28215 Bremen
Niveauschalter
Level switch
Commutateur de niveau
20
29
21
30
3sec.
6
14
7
15
SRL
1. / 2.
Funktionale Sicherheit
Functional safety
Sécurité fonctionnelle
IEC 61508
SIL 3
10 µS/cm
9
2
NRG 1...-50
1. / 2.
1
2
3
1345
10 11 12 13 16 17 23 24 26 27
NRS 1-50
MIN
+-
100-240 V ~
-15 / +10%
N
M 0,5A
L1. / 2.
+-
Name plate / marking
Fig. 5
Technical Data - continued -
Type designation
Mains voltage/
Protection
Serial number
Manufacurer
Wiring
diagram
Safety note
Disposal note
Type-approval no.
Ambient tempera-
ture / sensitivity
Wire link,
provided on site
Safety circuit
Fuse, provided
on site
Type designation
Mains voltage/
Protection
Serial number
Manufacurer
Wiring
diagram
Safety note
Disposal note
Type-approval no.
Ambient tempera-
ture / sensitivity
Wire link,
provided on site
Safety circuit
Fuse, provided
on site

12
Dimensions and Functional Elements
NRS 1-50
1Upper terminal strip
2Lower terminal strip
3Fixing screws (cross recess head screws M3)
4Enclosure
5Supporting rail type TH 35, EN 60715
Key
123456789101112131415
11
ON ON
22
12
2716 17 18 19 20 21 22 23 24 25 26 28 29 30
Test
Fig. 6
1
2
3
4
5
100
120
74

13
Safety note
This device is an item of equipment with safety function (PED) and 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 connecting
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.
Scope of supply
NRS 1-50
1 Level switch NRS 1-50
1 Installation manual
Important Notes

14
Electrical Connection
Connection of level electrode
Connect the safety circuit for the heating to terminals 23, 24 and 26, 27. Wenn used as water level
limiter according to TRD, EN 12952 / EN 12953 connect the output contacts of the two monitoring
channels by adding a wire link between the terminals 24 and 26.
Fuse the output contacts with a 2 A or 1 A (for 72 hours operation acc. to TRD 604) slow-blow fuse.
Connection of safety circuit
Installation
Mounting level switch NRS 1-50
The level switch NRS 1-50 is clipped onto the support rail type TH 35, EN 60715 in the control cabinet.
Fig. 6 5
For connecting the level switch with the logic unit use a control cable, e. g. 2 x 0.5 mm2.
The control voltage must not exceed 36 V DC.
Connection of logic unit (standby input)
Note
nIn the event of an alarm the level switch NRS 1-50 does not interlock automatically.
If an interlocking function in the installation is required, the follow-up circuit (safety
circuit) must be equipped with an interlock. The circuitry must meet the requirements
of the EN 50156.
Supply voltage
Fuse the level switch NRS 1-50 with an external semi-delay fuse 0.5 A.
To connect the level electrode please use:
nFor level switch NRS 1-50 with response sensitivity 10 μS:
Screened multi-core control cable, min. conductor size 0.5 mm2, e.g. LiYCY 4 x 0.5 mm2,
max. length 100 m.
nFor level switch NRS 1-50 with response sensitivity 0.5 μS:
Double-screened multi-core low-capacitance data cable, min. conductor size 0.5 mm2,
Li2YCY PiMF 2 x 2 x 0.5 mm2, max. length 30 m.
Wire terminal strip in accordance with the wiring diagram. Fig. 7. Connect screen to terminal 5 and the
central earthing point (CEP) in the control cabinet.

15
A signal output for the connection of further external signalling equipment is allocated to each monitor-
ing channel in the level switch, max. load 100 mA. For connecting the level switch with the logic unit
use a control cable, e. g. 2 x 0.5 mm2. In the event of an alarm or error message the signal output
(terminals 20, 21) opens instantaneously.
Connection for signal output
Electrical Connection - continued -
Tools
nScrewdriver for slotted screws, size 3.5 x 100 mm, completely insulated according to VDE 0680-1.
Danger
nFor the supply of the level switch NRS 1-50 with 24 V DC use a safety extra-low volt-
age (SELV) power supply unit that must be electrically isolated from dangerous contact
voltages and must meet at least the requirements on double or reinforced isolation
acc. to DIN EN 50178 or DIN EN 61010-1 or DIN EN 60730-1 or DIN EN 60950 (safe
isolation).
nAny item of equipment that you want to connect to terminals 6, 7 (standby input) must
be certified to have at least double or reinforced isolation according to DIN EN 50178
or DIN EN 61010-1 or DIN EN 60730-1 or DIN EN 60950 (safe electrical isolation)
between the standby inputs, the signal outputs and the live parts of the installation
that are not supplied with safety extra-low voltage (SELV).
Attention
nFuse the level switch NRS 1-50 with an external semi-delay fuse 0.5 A.
nConnect screen to terminal 5 and the central earthing point (CEP) in the control
cabinet.
nTo protect the switching contacts provide the safety circuit with a slow-blow fuse 2 A
or 1.0 A (for 72 hrs. operation acc. to TRD 604).
nWhen switching off inductive loads, voltage spikes are produced that may impair
the operation of control and measuring systems. Connected inductive loads must be
provided with suppressors such as RC combinations as specified by the manufacturer.
nWhen used as water level limiter according to TRD, EN 12952 / EN 12953 connect
terminals 24 and 26 by adding a wire link.
nInstall connecting lines to level electrode and logic unit separated from power cables.
nDo not use unused terminals as support point terminals.

16
2716
12345678
17 18 19 20 21 22 23 24
9
25
10
26
11 12
28
13
29
14
30
15
1
2
3
+
L
M 0,5A
(+)(-)
-
N
Test Test
*+-
Electrical Connection - continued -
Wiring diagram for level switch NRS 1-50
8Supply voltage
9Signal output 1 for external alarm 24 V DC 100 mA (semiconductor output)
0Safety circuit, input and output
aWire link, on site, when used as water level limiter acc. to TRD, EN 12952 / EN 12953
b Stand-by input, 24 V DC, for connecting the logic unit SRL 6-50
cLevel electrode NRG 1...-50, NRG 1...-11 or NRG 16-36
CEP Central earthing point in control cabinet
Key
* NRS 1-50 with response sensitivity 0.5 μS:
Connect the two internal screens to terminal 5 and
the CEP.
Fig. 7
CEP
+ –
L N
(+) (–)
80
a
0
b
c
– +
c
NRG 1..-50
NRG 1..-11
NRG 16-36
21
4
3
9
M 0.5A

17
d
ef
Fig. 8
d
e
f
Fig. 9
Electrical Connection - continued -
Schematic representations of arrangements
dd
geff
Fig. 10 Fig. 11
ee
dLevel electrode NRG 1...-50
eLevel switch NRS 1-50
Key
fSafety circuit
gLevel switch NRS 1-50 for low-level pre-alarm

18
Electrical Connection - continued -
Explanatory notes to schematic respresentations
Steam boiler plants and (pressurized) hot-water installations according to TRD 604,
EN 12952-07 / EN 12953-06, 72 h operation
Fig. 8
Combination consisting of 1 level electrode NRG 1...-50 and 1 level switch NRS 1-50 as water level
limiter. Functional safety IEC 61508, SIL 3.
For operation according to TRD 604, EN 12952-07 / EN 12953-06 (72 hours), two independent and
separate water level limiters must be used.
Hot water installations require two independent and separate water level limiters. For this purpose
one equipment combination NRG 1...-50/NRS 1-50 shall be installed in the hot-water boiler and the
second one in the pressure maintaining vessel, the expansion tank or the like (depending on the type
of pressurization). For electrically heated steam boilers one water level limiter is sufficient.
Further applications in accordance with national sets of regulations
Fig. 9
Combination consisting of 1 level electrode NRG 1...-50 and 1 level switch NRS 1-50 as water level
limiter. The level switch opens two separate safety circuits. Functional safety IEC 61508, SIL 3.
Fig. 10
Combination consisting of 1 level electrode NRG 1...-50 and 1 level switch NRS 1-50 as water level
limiter and 1 level electrode NRG 1...-50 / 1 level switch NRS 1-50 as low-level pre-alarm.
Functional safety IEC 61508, SIL 3.
Fig. 11
Combination consisting of 2 level electrodes NRG 1...-50 and 2 level switches NRS 1-50 as water level
limiter. The level switch opens two separate safety circuits. Functional safety IEC 61508, SIL 3.

19
Commissioning Procedure
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!
Basic Settings
Factory setting
Level Switch NRS 1-50
The level switch features the following factory set default values:
nDe-energizing delay: 3 sec., 15 sec. for marine applications.

20
Test Test
Commissioning - continued -
Checking switchpoint and function
Start
Activity Indication Function
Apply
mains voltage.
All LEDs are illuminated.
System is being started and tested,
this takes approx. 10 sec.
Output contacts are open.
Signal output is closed.
All LEDs are illuminated for more
than 10 sec.
System malfunction. Possible causes: Faulty
power supply, level switch defective.
Raise water in boiler until
the switchpoint “low water
level (LW)” is ecxeeded. Level
electrode enters the water.
Green LED
for level electrode is illuminated
Output contacts are closed.
Signal output opens.
Checking switchpoint and function
Lower water level until it is
below the switchpoint “low
water level (LW)”. Level
electrode is exposed.
Red LED
for level electrode is flashing
De-energizing delay is running.
Signal output is closed instantaneously.
Red LED
for level electrode is illuminated
Delay time has elapsed, output contacts open.
Signal output is closed.
Possible installation faults
Status and indication Fault Remedy
Sightglass indicates level
below switchtpoint “low
water (LW)”, red LED for level
electrode not illuminated.
Safety circuit closed.
Electrode rod is too long. Cut electrode rod to the length dictated by the
switchpoint LW.
If installed inside the boiler: Upper
vent hole in protection 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 sufficient.
Red LED for level electrode
is illuminated. Safety circuit
is open.
The electrode rod is too short. Replace electrode rod and cut new rod to the
length dictated by the switchpoint LW.
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.
Set response sensitivity of the level switch 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.
Level electrode
Test & diagnosis
button
LED alarm 1 /
operating mode
Test & diagnosis
button
Diagnosis LED
Fig. 12