GESTRA NRS 1-51 User manual

1
NRS 1-51
Installation Instructions 818955-04
Level Switch NRS 1-51
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
LV (Low Voltage) Directive and EMC (Electromagnetic Compatibility) .......................................................5
ATEX (Atmosphère Explosible).................................................................................................................6
UL/cUL (CSA) Approval............................................................................................................................6
Note on the Declaration of Conformity / Declaration by the Manufacturer ...........................................6
Safety characteristics of the subsystem NRG 1...-51 / NRS 1-51.............................................................7
Terms and abbreviations.........................................................................................................................7
Determination of the Safety Integrity Level (SIL) for safety-related systems.............................................8
Functional Safety acc. to IEC 61508
NRS 1-51..............................................................................................................................................12
Dimensions and Functional Elements
Safety note ...........................................................................................................................................13
Scope of supply....................................................................................................................................13
Important Notes
NRS 1-51.......................................................................................................................................... 9, 10
Name plate / marking ...........................................................................................................................11
Technical Data
Mounting level switch NRS 1-51...........................................................................................................14
Installation

3
Contents – continued –
Checking switchpoint and function .......................................................................................................18
Commissioning Procedure
Page
Indicators and adjustors........................................................................................................................19
Operation, Alarm and Test
Indication, diagnosis and remedy.................................................................................................... 19, 20
Troubleshooting
Action against high frequency interference ...........................................................................................21
Interlock and interlock deactivation.......................................................................................................21
Checking the switchpoints....................................................................................................................21
Decommissioning / replacing level switch.............................................................................................21
Disposal................................................................................................................................................21
Further Notes
Electrical Connection
Connection of supply voltage ................................................................................................................14
Connection of level electrode................................................................................................................14
Connection of control circuit .................................................................................................................14
Connection of logic unit (standby input).................................................................................................15
Connection for signal output .................................................................................................................15
Tools.....................................................................................................................................................15
Wiring diagram for level switch NRS 1-51.............................................................................................16
Schematic representations of arrangements.........................................................................................17
Explanatory notes to schematic respresentations..................................................................................17
Factory setting......................................................................................................................................17
Basic Settings

4
Application
Usage for the intended purpose
The level switch NRS 1-51 is designed for different electrical conductivities of the boiler water and for
connecting one level electrode.
See section Schematic representations of arrangements on page 16.
When the water level exceeds the MAX limit, the level electrode enters the liquid and an alarm is
triggered in the level switch. This switchpoint is determined by the length of the electrode rod
(level electrode NRG 1...-51, NRG 1...-12).
After the de-energizing delay has elapsed, both output contacts of the level switch will open the control
circuit, e. g. for the feedwater supply. If the deactivation of the feedwater supply is interlocked in the
external control circuit, the lockout can only de deactivated when the level electrode is exposed again.
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 connecting
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 autmatic self-testing routine monitors the safety functions of the level switch. In the event of a
malfunction the control circuit opens instantaneously and switches off e. g. the feedwater supply.
Alarm and malfunction messages are indicated by LEDs, and the signal output is instantaneously
energized.
An alarm can be simulated by pressing the test button.
Function
The level switch NRS 1-51 is used in conjunction with level electrodes NRG 1...-.. as high level alarm in
steam boilers and (pressurised) hot-water plants.
A high level alarm prevents the water level from exceeding the preset max. water level (HW) and for this
purpose switches off e. g. the feedwater supply.
Depending on the specified directives or standards, the level switch NRS 1-51 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 16-51 NRG 17-51 NRG 19-51
VdTÜV Bulletin “Wasserstand 100”
(= Water Level 100)
NRG 16-51
NRG 16-12
NRG 17-51
NRG 17-12
NRG 19-51
NRG 19-12
Note
nA high level alarm prevents the water level from exceeding the preset max. liquid
level (HW). For this purpose it can, for instance, interrupt the feedwater supply. If the
interruption of the feedwater supply endangers the heating surfaces in the feedwater
preheater (economizer), the heating must be switched off, too.

5
Directives and Standards
Pressure Equipment Directive (PED) 2014/68/EU
The level switch NRS 1-51 in conjunction with level electrode NRG 1...-51 is EC type approved
according to EN 12952/EN 12953. These Directives state, among other things, the requirements 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 1-51 in conjunction with the level electrodes NRG 1...-51 and NRG 1...-12 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 1-51 is certified acc. to IEC 61508 only if used in combination with level elec-
trode NRG 1...-51. This standard describes the functional safety of safety-related electrical/electronic/
programmable electronic systems.
The equipment combination NRG 1...-51 + NRS 1-51 corresponds to a type B subsystem with Safety
Integrity Level (SIL) 3.
LV (Low Voltage) Directive and EMC (Electromagnetic Compatibility)
The level switch NRS 1-51 meets the requirements of the Low Voltage Directive 2014/35/EU and the
EMC Directive 2014/30/EU.

6
ATEX (Atmosphère Explosible)
According to the European Directive 2014/34/EU the level switch NRS 1-51 must not be used in
potentially explosive areas.
Note
The level electrodes NRG 1...-51, NRG 1...-12 are simple items of electrical equipment as
specified in EN 60079-11 section 5.7. According to the European Directive 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...-51,
NRG 1...-12 + Zener barriers + NRS 1-51 are interconnected!
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.
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...-51 / NRS 1-51
The level switch NRS 1-51 is certified acc. to IEC 61508 only if used in combination with level electrodes
NRG 1...-51.
The equipment combination NRG 1...-51 / NRS 1-51 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
detection 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...-51 / NRS 1-51 corresponds to the architecture
1oo2. This architecture consists of two channels that detect and diagnose faults in each other. If a fault
is detected, the equipment combination NRG 1...-51 / NRS 1-51 will go to the safe state, which means
that the contacts of both output relays will open the control circuit.
Safety characteristics SIL Architecture Lifetime
(a)
Proof Test
Interval (a)
General 3 1oo2 20 20
SFF PFDav PFHav λDU
Level switch NRS 1-51 alone 98.54 % 1.18 x 10-4 3.73 x 10-8 7.33 x 10-8 /h
Level switch NRS 1-51 in conjunction with one
level electrode NRG 1...-51
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 contactors in control 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 control 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 1-51
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
Electrical connection of level electrode
1 input for level electrode NRG 1...-51, NRG 1...-12, 4-poles with screen
Sensitivity 0.5 μS/cm or 10 μS/cm (at 25 °C).
Stand-by input
1 volt-free input, 18-36 VDC, for monitoring the purging and bypass time.
Max. bypass time: 5 minutes.
Control circuit
2 volt-free make contacts, 6 A 250 V AC / 30 V DC cos ϕ= 1.
Delay of response: 3 seconds.
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 V DC, 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.
Cross section of connection: 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 1-51 – continued –
Further conditions:
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 electrical/
SIL 3 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 · SHWS · XX-423
(see name plate)
UL/cUL (CSA) Approval UL 508 and CSA C22.2 No. 14-13, Standards for Industrial Control
Equipment. File E243189.
Technical Data – continued –

11
Name plate / marking
Technical Data – continued –
Fig. 5
Type designation
Supply voltage/
Protection
Manufacturer
Wiring
diagram
Safety note
Disposal note
Type approval no.
Ambient temperature /
sensitivity
Wire link,
provided on site
Control circuit
Fuse, provided on site
Type designation
Supply voltage/
Protection
Manufacturer
Wiring
diagram
Safety note
Disposal note
Type approval no.
Ambient temperature /
sensitivity
Wire link,
provided on site
Control circuit
Fuse, provided on site
Serial number
Serial number
TÜV · SHWS · XX-423
TÜV · SHWS · XX-423

12
Dimensions and Functional Elements
NRS 1-51
1Upper terminal strip
2Lower terminal strip
3Fixing screws (cross recess head screws M3)
6Enclosure
7Supporting rail type TH 35, EN 60715
Key
Fig. 6
1
2
3
6
7
100
118
73

13
Safety note
High water level alarms are safety devices 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 NRS 1-51 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 1-51
1 Level switch NRS 1-51
1 Installation manual
Important Notes

14
Electrical Connection
Connection of level electrode
Connect the control circuit for the feedwater supply / heating to terminals 23, 24 and 26, 27. Wenn
used as high water level alarm to TRD, EN 12952 / EN 12953 connect the output contacts of both
monitoring channels by fitting 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 control circuit
Installation
Mounting level switch NRS 1-51
The level switch NRS 1-51 is clipped onto the support rail 7type TH 35, EN 60715 in the control
cabinet. Fig. 6
Note
nA high level alarm prevents the water level from exceeding the preset max. liquid
level (HW). For this purpose it can, for instance, interrupt the feedwater supply. If the
interruption of the feedwater supply endangers the heating surfaces in the feedwater
preheater (economizer), the heating must be switched off, too.
nIn the event of an alarm the level switch NRS 1-51 does not interlock automatically.
If a lockout function is required by the installation it must be provided in the follow-up
circuitry (control circuit). The circuitry must meet the requirements of the EN 50156.
Connection of supply voltage
Provide the level switch NRS 1-51 with an external semi-delay fuse 0.5 A. If the equipment is supplied
with 24 V DC use a safety 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:
DIN EN 50178, DIN EN 61010-1, DIN EN 60730-1 or DIN EN 60950.
To connect the level electrode please use:
nFor level switch NRS 1-51 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 1-51 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 screens to terminal 5 and to
the central earthing point (CEP) in the control cabinet.

15
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)
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 1-51 with 24 V DC use a safety extra-low
voltage (SELV) power supply unit that must be electrically isolated from dangerous
contact voltages and must meet at least the requirements on double or reinforced iso-
lation acc. to DIN EN 50178 or DIN EN 61010-1 or DIN EN 60730-1 or DIN EN 60950
(safe electrical isolation).
nAny item of equipment that you want to connect to terminals 6, 7 (standby input 1)
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 and the live parts of the installation that are not
supplied with safety extra-low voltage (SELV).
Attention
nFuse the level switch NRS 1-51 with an external semi-delay fuse 0.5 A.
nConnect screens to terminal 5 and to the central earthing point (CEP) in the control
cabinet.
nTo protect the switching contacts fuse the safety circuit with a slow-blow fuse 2 A or 1
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 pro-
vided with suppressors such as RC combinations as specified by the manufacturer.
nWhen used as high water level alarm according to TRD, EN 12952 / EN 12953 connect
terminals 24 and 26 by fitting a wire link.
nInstall connecting lines to level electrodes and logic unit separated from power cables.
nDo not use unused terminals as support point terminals.
A signal output for the connection of external signalling equipment is allocated to the monitoring
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) closes instantaneously.
Connection for signal output

16
Electrical Connection – continued –
Wiring diagram for level switch NRS 1-51
8Mains supply
9Signal output 1 for external alarm 24-230 V AC/DC 100 mA
0Control circuit, input and output
aWire link, fitted on site, when used as high water level alarm acc. to TRD, EN 12952 / EN 12953
b Stand-by input 1, 24 V DC, for connecting the logic unit SRL 6-50
cLevel electrode NRG 1...-51, NRG 1...-12
CEP Central earthing point in control cabinet
Key
2716
12345678
17 18 19 20 21 22 23 24
9
25
10
26
11 12
28
13
29
14
30
15
Test
*
Fig. 7
L N
(+) (–)
89
0
a
0
b
c
– +
*
CEP
* NRS 1-51 with response sensitivity 0.5 μS/cm:
Connect the two internal screens to terminal 5 and
the CEP.
M 0.5A

17
dd
e
e
ff
Fig. 8 Fig. 9
Electrical Connection – continued –
Schematic representations of arrangements
Key
Steam boiler plants according to TRD 604, EN 12952-07 / EN 12953-06, 72 h operation
Fig. 8
Combination consisting of 1 level electrode NRG 1...-51 and 1 level switch NRS 1-51 as high water level
alarm. Functional safety IEC 61508, SIL 3.
Further applications in accordance with national sets of regulations
Fig. 9
Combination consisting of 1 level electrode NRG 1...-51 and 1 level switch NRS 1-51 as high water level
alarm
. The level switch opens two separate control circuits. Functional safety IEC 61508, SIL 3.
dLevel electrode(s) NRG 1...-51
eLevel switch NRS 1-51
fControl circuit
Basic Settings
Factory setting
Level Switch NRS 1-51
The level switch features the following factory set default values:
nDe-energizing delay: 3 sec.
Commissioning Procedure
Danger
The terminal strips of the NRS 1-51 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!

18
Commissioning Procedure – 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 1 closed.
All LEDs are illuminated for more
than 10 sec.
System malfunction. Possible causes:
Faulty power supply, level switch defective.
Lower water level in boiler
until the level falls below
the switchpoint high water
level (HW). Level electrode is
exposed.
Green LED
for level electrode 1 is illuminated
Output contacts are closed.
Signal output 1 is open.
Checking switchpoint and function
Raise level in boiler until the
switchpoint “high water level
(HW)” is ecxeeded. Level
electrode enters the water.
Red LED
for level electrode 1 is flashing
De-energizing delay is running.
Signal output 1 is closed instantaneously.
Red LED
for level electrode 1 is illuminated
Delay time has elapsed, output contacts open.
Signal output 1 is closed.
Possible installation faults
Status and indication Fault Remedy
Sightglass indicates high
water level (HW) exceeded,red
LED for level electrode 1 is
not illuminated. Safety circuit
closed.
The electrode rod is too short. Replace electrode rod and cut new rod to the
length dictated by the switchpoint HW.
The earth connection to the vessel
is interrupted.
Clean seating surfaces and screw in level
electrode 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.
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 cor-
responds to the actual water level.
Water level sufficient. Red
LED for level electrode 1 is
illuminated. Safety circuit is
open.
Electrode rod is too long. Cut electrode rod to the length dictated by the
switchpoint HW.
Upper vent hole flooded.
Check installation of level electrode. Make
sure that the level in the protection tube
corresponds to the actual water level.
Fig. 14
TÜV.SHWS . 09-423 0525
Level electrode 1
Test & diagnosis
button
LED alarm 1 /
operating mode
Diagnosis LED

19
Operation
Activity Indication Function
Level electrode exposed Green LED
for level electrode 1 is illuminated
Output contacts are closed.
Signal output 1 is open.
Alarm
Level electrode submerged,
high water level (HW)
exceeded.
Red LED
for level electrode 1 is flashing
De-energizing delay is running.
Signal output 1 is closed instantaneously.
Red LED
for level electrode 1 is illuminated
Delay time has elapsed, output contacts open.
Signal output 1 is closed.
Test channel 1
During operation:
Press and hold down key 1
until the end of the test, level
switch must function as if there
were an alarm.
Red LED
for level electrode 1 is flashing
Alarm simulated in channel 1 or 2.
De-energizing delay is running.
Signal output 1 is closed instantaneously.
Red LED
for level electrode 1 is illuminated
Delay time has elapsed, output contacts open.
Signal output 1 is closed. Test finished.
Replace level switch if the test was not finished successfully.
Operation, Alarm and Test
Indicators and adjustors
Attention
Before carrying out the fault diagnosis please check:
Mains supply:
Is the level switch supplied with the supply voltage specified on the name plate?
Wiring:
Is the wiring in accordance with the wiring diagram and the relevant schematic
representation of arrangement?
Troubleshooting
Indication, diagnosis and remedy
Fig. 14
TÜV.SHWS . 09-423 0525
Level electrode 1
Test & diagnosis
button
LED alarm 1 /
operating mode
Diagnosis LED

20
Diagnosis
Display 1 and activity Display 2 Fault Remedy
LED alarm 1 and
diagnosis LED 1
illuminated. Press and hold
down key 1.
Diagnosis
LED 1
flashing.
Malfunction in level
electrode 1, malfunction in
level switch, faulty wiring,
faulty measuring voltage. Check wiring,
replace level switch.
Diagnosis
LED 2
flashing.
Malfunction in level
electrode 1, malfunction in
level switch, faulty wiring.
Diagnosis
LED 3
flashing.
Interference voltage causing
malfunction, boiler earth
without PE
Provide screen and earthing, connect
boiler with PE.
LED alarm 1 or 2
and Diagnosis LED 3
illuminated. Press and hold
down key 1 or 2.
Diagnosis
LED 1
flashing.
Malfunction in processor,
stand-by fault.
Observe operating instructions for the
logic unit SRL. Replace level switch.
Diagnosis
LED 2
flashing.
Internal voltage fault.
Replace level switch.
Diagnosis
LED 3
flashing.
Malfunction in relay.
Once the fault is eliminated, the level switch returns to normal operation.
After elimination of the fault switch off the supply voltage and switch it on again after approx. 5 sec.
Further fault indications
Status Diagnosis Function Next activity
Faulty evaluation of level
electrode 1, channel 1
Diagnosis LED 1 and
LED alarm 1 illuminated.
Output contacts are opened instantaneously.
Signal output 1 closes instantaneously.
next:
Press key 1.
Malfunction in level
switch detected.
Diagnosis LED 3 and
LED alarm 1 or 2
illuminated.
Output contacts are opened instantaneously.
Signal outputs 1/2 are closed instantaneously.
next:
Press key 1
or key 2.
Troubleshooting – continued –
Indication, diagnosis and remedy – continued –
Malfunction in level electrode
Status and indication Fault Remedy
Water level sufficient. Red
LED for level electrode 1 is
illuminated. Safety circuit is
open.
The insulation of the level
electrode is dirty or faulty. Clean or, if necessary, replace level electrode.
If faults occur that are not listed above or cannot be corrected, please contact our service centre or
authorized agency in your country.