Belimo SRA-100 User manual

Technical manual BA 0113
Filling level
SRA – 100 8M
Filling level limit switch
for conductive filling level supervision
in electrical conductive liquids
Useable
 for filling level resp. limit value detection in liquid container
 as dry run protection for pumps
 for two-position-control in plants
ATEX II (1) G [Ex ia Ga] IIB/IIC resp. ATEX II (1) D [Ex ia Da] IIIB/IIIC
Certification for the connection of conductive level transducer in explosion
hazardous areas
Measuring range adjustable up to 8M resp. 0,125µS/cm
Different configurable switching delays
Wide range power supply from 20 to 253V AC and DC
L a u t e r b a c h s t r . 5 7 – 8 4 3 0 7 E g g e n f e l d e n – G e r m a ny
T e l : + 4 9 8 7 2 1 / 9 6 6 8 - 0 – F a x : + 4 9 8 7 2 1 / 9 6 6 8 - 30
i n f o @ a c s - c o n t r o l s y s t e m . d e – w w w . a c s - c o n t r o l s y s t e m . d e

SRA – 100 8M
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Index
Order code ..................................................................................................................... 2
Application .................................................................................................................... 3
Function .................................................................................................................... 3 / 4
Safety notes ................................................................................................................... 5
Safety notes ............................................................................................................. 5
Installation ...................................................................................................................... 5
Maintenance ................................................................................................................... 5
Repair ............................................................................................................................. 5
Electrical connection .................................................................................................... 6
Operation and display elements .................................................................................... 7
Technical data ............................................................................................................... 8
Order code
SRA – 100 – U0 8M Basic variant
ExSRA – 100 – U0 8M Variant with certification acc. to ATEX

SRA – 100 8M
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Application
The filling level limit switch SRA – 100 8M is used, to evaluate one or two filling levels resp. limit levels in
electrically conductive liquids with a conductivity of minimum 0,125µS/cm resp. a resistance of maximum 8M.
For the connection of level resp. measurement transducer in explosion hazardous areas, the device is equipped
with two intrinsically safe supply and signal circuits.
Function
Measuring principle
The signal circuit of the filling level limit switch is connected to the reference electrode or the metallic wall of the
container resp. pipe and to the measuring electrode.
The alternating voltage, that is generated by the integrated electronic is than applied either between the
electrode rods or between the electrode rods and the metallic wall of the container resp. pipe that is connected
to the metallic process connection, realizing the reference electrode.
Due to the use of a alternating voltage the corrosion at the electrode rod and the electrolytic decomposition of
the filling liquid is avoided.
As soon as the electrically conductive liquid makes a connection between the electrodes resp. between the
electrode and the metallic wall of the container resp. pipe, an alternating current flows, that causes a decrease
of the alternating voltage.
Signal evaluation
An evaluation circuit supervises this alternating voltage. A voltage drop is detected and the evaluation circuit
switches the relay resp. relays, depending on the set safety function.
The switching state of the relays is indicated at the front side of the device by two yellow LED’s.
Switching delay
In some applications it is necessary to compensate heavy signal fluctuations that may be produced by mixing
machines or at fill-in resp. emptying of containers, to avoid spurious switching actions.
Two switches at the front side of the device allows the configuration of a switching delay of 0,5 / 3 / 5 / 8 s.
This delay time effects both channels separately, at activation and deactivation of the filling level relays.
Sensitivity range
The device can be adjusted in the resistance range 1 to 8 M. Within this range a fine adjustment can be
carried out by a trimmer at the front side of the device.
Configuration of the second output relay S2
The second output relay can be configured in two operation modes:
 2nd filling level relay to electrode at CH1 (relay switches like filling level relay S1 – parallel mode)
 Filling level relay to electrode at CH2 (two channel mode: CH1 to S1 / CH2 to S2)

SRA – 100 8M
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Safety function
The safety function defines the operation principle of the output relays
 Maximum safety: The relay switches off, if the switching level is transgressed
(liquid connection between measuring and reference electrode),
or the power supply fails.
 Minimum safety: The relay switches off, if the switching level is underrun
(no liquid connection between measuring and reference electrode),
or the power supply fails.
For the function two-position-control the safety function must be set identically for both channels, CH1 and CH2.
This can be carried out by two switches, one per channel, at the front side of the filling level limit switch.
Two-position-control s (pump control)
The activation of the two-position-control is made by a switch at the front side of the device.
Two-position-control with minimum safety Two-position-control with maximum safety
at parallel mode relay S1 and S2 at parallel mode relay S1 and S2
For the function two-position-control the safety function must be set identically for both channels, CH1 and CH2.
This can be carried out by two switches, one per channel, at the front side of the filling level limit switch.

SRA – 100 8M
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Safety notes
Each person that is engaged with inauguration and operation of this device, must have read and
understood this technical manual and especially the safety notes.
Installation, electrical connection, inauguration and operation of the device must be made by a qualified
employee according to the informations in this technical manual and the relevant standards and rules.
The device may only be used within the permitted operation limits that are listed in this technical manual.
Every use besides these limits as agreed can lead to serious dangers.
The device meets the legal requirements of all relevant EC directives.
Safety notes for electrical operating supplies
for explosive hazardous areas
If a device is installed and operated in explosive hazardous areas, the general Ex construction standards
(EN/IEC 60079-14, VDE0165), this safety notes and the enclosed EC conformity certificate must be observed.
The installation of explosive hazardous systems must be carried out principally by specialist staff.
The device meets the classification: II (1) G [Ex ia Ga] IIB/IIC resp. II (1) D [Ex ia Da] IIIB/IIIC
The device is conceived for detection of limit levels at liquids in explosive hazardous areas, that needs devices
of category 1 resp. category 1/2.
The measured medium may also be combustible liquids.
The filling level limit switch is a affiliated operating supply and may only be used outside explosion hazardous
areas.
Installation
The filling level limit switch is conceived for vertical installation on a standard fastening rail acc. to
EN/IEC 60715 TH 35-7,5 resp. TH35-15.
EN/IEC 60715 TH 35-7,5
EN/IEC 60715 TH35-15
The device must be installed protected against dust and humidity, e.g. in control stations or in a suitable
protection housing with a minimum protection classification IP55 acc. to EN/IEC 60529.
The devices must be installed wheather and stroke protected, ideally at places without direct solar radiation.
This is especially important in warm climatic regions.
Maintenance
The device is free of maintenance.
Repair
A repair may only be carried out by the manufacturer. When sending back the device, add a note with the
description of the error and the application.
0158

SRA – 100 8M
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Electrical connection
The electrical connection of the device must be carried out according to the respective country specific
standards. Incorrect installation or adjustment could cause applicationally conditioned risks.
Power supply input, measuring input and relay output channels are safe galvanically isolated from each other.
This is also valid for both relay output channels among each other.
Connection of the signaling transmitter resp. measuring transducer – measuring inputs
For the two or three-wire connection cable between the filling level limit switch and the signaling transmitter
resp. measuring transducer a standard installation cable or multi-wire cable for measuring intends with a
maximum of 25  per wire can be used.
The use of a shielded signal cable is not required in principle, but is recommended, if strong electromagnetic
influences could happens, e.g. due to machines or radio equipment. In that case the shielding of the cable
should be connected to earth only at the side of signaling transmitter resp. measuring transducer.
The signal cable should be installed separated from power leading wires.
If more than two limit levels with the same reference potential should be evaluated, several filling level limit
switches could be connected in parallel. For this purpose only the reference connection of all devices must be
connected with each other (see scheme below - right).
Connection of the signaling and control equipments – relay outputs
Inductive loads at the relay contacts, e.g. auxiliary contactors or magnetic vents may only be used with a free-
wheeling diode or a RC protection circuit to avoid high voltage peaks.
For inauguration it is suggested, to deactivate all connected control devices, to avoid unwanted control
reactions.
Connection of the power supply voltage
Due to the integrated wide range power supply, for connection to supply voltages from 20...253V AC / DC, the
filling level limit switch is suitable for using in all common energy supply networks.
At variants with ATEX certificate, the supply voltage range is 20...253V AC resp. 20...125V DC.
The connection is reverse polarity protected.
A switch, that is marked as separator as well as a over current protection switch (nominal current  10 A) must
be installed near the device into the supply lead.
single channel operation two channel operation four channel operation
resp. by parallel connection of two
two-position-control s filling level limit switch SRA – 100

SRA – 100 8M
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Operation and display elements
Function indicator
 ON  green LED  ready status, power supply voltage on
 FAIL  not supported
 S1  yellow LED  output relay S1 switched on
 S2  yellow LED  output relay S2 switched on
Adjustment trimmer
For fine adjustment of the response sensitivity within the sensitivity range.
A turn to the right leads to a switching reaction at a higher liquid resistance.
For adjustment proceed like follows:
 Liquid must create an electrically conductive connection between measuring and reference electrode of the
connected measuring transducer
 Turn adjustment trimmer to the left (counterclockwise), till the output relays switches off
 Turn adjustment trimmer to the right (clockwise), till the output relay switches on
 Turn adjustment trimmer by an additional half turn to the right (clockwise)
Configuration switches
Switch 1, 2, 3  no function
switch
switching state
1
OFF
2
OFF
3
OFF
Switch 4  function output relay S1
switch
switching state ON
switching state OFF
4
two-position-control s
limit level function
Switch 5  safety function channel 1 (CH1)
switch
switching state ON
switching state OFF
5
minimum safety
maximum safety
Switch 6  safety function channel 2 (CH2)
switch
switching state ON
switching state OFF
6
minimum safety
maximum safety
Switch 7  no function
switch
switching state
7
OFF
Switch 8, 9  time delay for both channels CH1 / CH2
switching state S8
switching state S9
time delay
ON
ON
0,5 seconds
OFF
ON
3 seconds
ON
OFF
5 seconds
OFF
OFF
8 seconds
Switch 10, 11, 12  configuration output relay S2
S 10
S 11
S 12
function output relay S2
OFF
OFF
ON
2nd filling level relay at CH1 (maximum electrode) – parallel mode
ON
OFF
OFF
filling level relay at CH2 (minimum electrode) – two channel mode
OFF
OFF
OFF
output relay S2 deactive
Configuration switches
12 DIL switches,
for setting the desired
functionality
Function indicator
3 LED’s for indication
of operating states
Adjustment trimmer
for fine adjust of the
response sensitivity
within the configured
sensitivity range
S2
S1
Fail
ON

SRA – 100 8M
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Technical data
Auxiliary power supply
Permitted supply voltage: Basic variant 20 V to 253 V AC / DC 48...62 Hz,
ATEX variant 20 V to 253 V AC 48...62 Hz resp. 20...125V DC
reverse polarity protected
Power consumption:  3,5 VA / 1,3 W
Overvoltage category: II acc. to EN/IEC 61010-1
Protection classification: II double or reinforced insulation
Isolation voltage: 4kV~ Auxiliary power to relay outputs to signal inputs
Galvanic isolation: All supply, input and output channels among each other as well as both relay outputs
from each other are safe galvanically isolated.
Relay outputs
Function: 2x potential-free changeover contact
Switching power of the contacts: U~ maximum 253 V AC
I~ maximum 10 A AC
P~ maximum 2500 VA at ohmic load / 500 VA at cos ≥ 0,7
for use of connection of level resp. measuring transducer in
explosion hazardous areas max. 250V AC / 5 A / 100 VA
at U-
maximum I-
maximum P-
30 V
10 A
5 A at ATEX variant
300 W
100 W at ATEX variant
110 V
0,3 A
33 W
220 V
0,12 A
26,4 W
Switching cycles:  100.000 switching cycles at maximum contact load
Signal inputs
Level transducer: One resp. two filling level electrodes with common reference electrode
Supply voltage:   10 V (90 Hz  15 Hz)
Supply current:   1 mA
Measuring range:  8M resp.  0,125µS/cm
Materials
Connection housing: PA – polyamide
Terminal housing: PA – polyamide
Sticker: PE – polyester
Connection terminals
Number: 3 terminal blocks with each 4 terminals, everlasting screws
Connection cross-section: maximum 1 x 2,5 mm or 2 x 1,5 mm
Housing style
Housing: Series installation housing, 22,5mm wide
Weight: 145 g
Environmental conditions
Environmental temperature: Single installation – 40°C...+85°C resp. -20°C..+60°C at ExSRA-100-U0
Series installation – 40°C...+70°C resp. -20°C..+50°C at ExSRA-100-U0
Protective housing – 40°C...+50°C resp. -20°C..+40°C at ExSRA-100-U0
Climatic classification: 3K3 resp. 3M2 EN/IEC 60721-3-3
Protection classification: IP20 EN/IEC 60529
EM – compatibility: emission EN/IEC 61326-1 operation device class B
immunity EN/IEC 61326-1 industrial range