MSR ELECTRONIC SC2 Series User manual

PolyGard/ µGard® are registered trademarks of MSR Made in Germany GA_SC2_MC2_Freon_D_0321
Phone [phone] Specification subject to change without notice
MSR-Electronic GmbH, Buergermeister-Schoenbauer-Str. 13, D 94060 Pocking www.msr-electronic.de
PolyGard2 / µGard2 Sensors for Refrigeration Applications
Sensor Cartridge for Freon Gases and Refrigerants
Series: SC2 and MC2 Series
User Manual
March 2021
Up-to-date data sheets and user manuals can be found in the download area of www.msr-24.com.

User Manual - PolyGard®2 / µGard®2
Sensor for Freon Gases and Refrigerants
Page 2
PolyGard/ µGard® are registered trademarks of MSR Made in Germany GA_SC2_MC2_Freon_D_0321
Phone [phone] Specification subject to change without notice
MSR-Electronic GmbH, Buergermeister-Schoenbauer-Str. 13, D 94060 Pocking www.msr-electronic.de
1Functional Description........................................................................................................................ 3
1.1 General ................................................................................................................................................................. 3
1.2 Measuring Mode................................................................................................................................................. 3
1.3 Special Mode....................................................................................................................................................... 3
1.4 Sensor Element for Freon Gases .................................................................................................................... 3
2Installation.......................................................................................................................................... 4
2.1 Mounting Instructions....................................................................................................................................... 4
3Electrical Connection .......................................................................................................................... 4
3.1 Plug Connection (SC2) in SB2, MSB2, MSC2, WSB2 ................................................................................... 4
3.2 Terminal Connection (MC2)............................................................................................................................. 4
4Commissioning ................................................................................................................................... 5
4.1 Installation of Sensor Cartridge ..................................................................................................................... 5
4.2 Registration of the Sensor Cartridge............................................................................................................. 5
5Calibration .......................................................................................................................................... 5
5.1 Calibration Work ................................................................................................................................................ 6
5.1.1 Procedure for Calibration with Tool or Display...................................................................................... 6
5.1.2 Extended Calibration .................................................................................................................................... 6
5.2 Exchange of Sensor Cartridge......................................................................................................................... 7
6Inspection and Service ........................................................................................................................ 7
6.1 Inspection ............................................................................................................................................................ 7
6.2 Service and Calibration .................................................................................................................................... 8
7Troubleshooting ................................................................................................................................. 8
7.1 Indicators at the SC2 ......................................................................................................................................... 8
7.2 Indicators at the MC2 ........................................................................................................................................ 8
7.3 Sensor Board (PCB) ............................................................................................................................................ 8
7.4 Sensor Cartridge (Messages at the Tool / Controller)............................................................................... 9
8Technical Data..................................................................................................................................... 9
8.1 MC2........................................................................................................................................................................ 9
8.2 Sensor Cartridge (SC2)....................................................................................................................................10
8.3 Sensor Element.................................................................................................................................................10
9Figures .............................................................................................................................................. 11
10 Part Disposal .................................................................................................................................. 12
11 Notes and General Information ...................................................................................................... 12
11.1 Intended Product Application...................................................................................................................12
11.2 Installers’ Responsibilities ........................................................................................................................12
11.3 Maintenance..................................................................................................................................................12
11.4 Limited Warranty .........................................................................................................................................12

User Manual - PolyGard®2 / µGard®2
Sensor for Freon Gases and Refrigerants
Page 3
PolyGard/ µGard® are registered trademarks of MSR Made in Germany GA_SC2_MC2_Freon_D_0321
Phone [phone] Specification subject to change without notice
MSR-Electronic GmbH, Buergermeister-Schoenbauer-Str. 13, D 94060 Pocking www.msr-electronic.de
Intended Use
The PolyGard2 sensors are designed for the measurement of refrigerant Freon gases mainly in refrigeration
plants and only in connection with the basic units SB2, MSC2, MSB2 and WSB2 of the PolyGard2 series.
The MC2 sensor (µGard2) is operated with 24 V DC and outputs an analog 4–20 mA standard signal.
The PolyGard2 / µGard2 sensors must not be used in potentially explosive atmospheres. The sensor must
only be employed in areas within the environmental conditions specified in the Technical Data.
1Functional Description
1.1 General
The Sensor Cartridge includes a µController for measurement value processing in addition to the gas sensor
element and the measuring amplifier. All data and measured values of the sensor element are stored in a
fail-safe way in the µController and are digitally transferred via the local bus to PCB. The calibration
management is also integrated in the µController of the Sensor Cartridge.
The Sensor Cartridge SC2 is connected to the SB2 / MSB2 / MSC2 / WSB2.
The µCartridge MC2 works according to the same principle as the SC2 series with the exception that the MC2
outputs an analog signal of 4–20 mA (2–10 V as an option).
1.2 Measuring Mode
See description of the SB2, MSC2, MSB2 and WSB2 devices.
1.3 Special Mode
See description of the SB2, MSC2, MSB2 and WSB2 devices.
1.4 Sensor Element for Freon Gases
Semiconductor gas sensors (metal oxide sensors) are electrical conductivity sensors. The resistance of its
sensitive layer changes upon contact with the gas to be detected. The gas then reacts with the sensor
surface. This reaction is reversible in the ideal case. Due to their chemical properties metal oxide gas sensors
are suitable for a wide range of applications and the detection of all reactive gases. Depending on the
materials used and the gases to be detected, common operating temperatures in the semiconductor sensor
are between 300 °C and 900 °C. The signal is double logarithmic to the gas concentration –not linear. The
current is evaluated by the subsequent measuring amplifier and converted into a linear output signal.
Oxidation processes lead by-and-by to an unwanted influence on the alteration of the conductivity.
Therefore, regular calibrations of zero-point (Zero) and gain are necessary (see section 5).
Certain substances and gases in the monitored ambient can affect the sensitivity of the sensor
element or destroy the sensor completely. This is called poisoning.
The following are currently known:
•Polymerising substances, such as ethylene oxide, acrylonitrile, butadiene, styrene, silicone.
•Catalytic poisons, such as sulphur and phosphor compounds, silicon compounds, metal vapours.
•Organic solvents.
Semiconductor sensors are not linear on principle. This means that the sensor would only measure
accurately on the calibrated point and not over the entire measuring range. Therefore, a linearization is
included in our software to improve this behaviour. But since the sensor resistance of a semiconductor
elements may be very different (between 0.5–40 kΩ), it must be normalized. This can be done via the
potentiometer on the PCB. Thus, the different output signals can be changed accordingly and adjusted
appropriately.

User Manual - PolyGard®2 / µGard®2
Sensor for Freon Gases and Refrigerants
Page 4
PolyGard/ µGard® are registered trademarks of MSR Made in Germany GA_SC2_MC2_Freon_D_0321
Phone [phone] Specification subject to change without notice
MSR-Electronic GmbH, Buergermeister-Schoenbauer-Str. 13, D 94060 Pocking www.msr-electronic.de
2Installation
Electronics can be destroyed by electrostatic discharge (ESD). Therefore, the installation work
should be done only by persons connected to ground, e. g. by standing on a conductive floor or
by taking appropriate grounding measures (acc. to DIN EN 100015).
2.1 Mounting Instructions
See description of the SB2, MSC2, MSB2 and WSB2 devices.
When choosing the mounting site please pay attention to the following:
•The mounting height depends on the relative density of the gas type to be monitored.
Gas type
Relative density
(air = 1)
Recommended
mounting height
Calibration
interval
All Freon gases
> 1
0.3 m above floor
12 months
•Choose mounting location of the sensor according to the local regulations.
•Consider ventilation conditions! Do not mount the sensor near the airflow (air passages. suction
holes etc.).
•Mount the sensor at a location with minimum vibration and minimum variation in temperature
(avoid direct sunlight).
•Avoid locations where water, oil etc. may influence proper operation and where mechanical damage
might be possible.
•Provide adequate space around the sensor for maintenance and calibration work.
3Electrical Connection
3.1 Plug Connection (SC2) in SB2, MSB2, MSC2, WSB2
SC2 sensors are equipped with a reverse polarity protected connector (3-pin). It must not be plugged in
the wrong position by force (already clamped at the factory).
All black plugs are connected in parallel, so it is irrelevant which plug to use.
3.2 Terminal Connection (MC2)
•Open cover.
•Insert field bus cable from above, cut and strip it.
•Connect it to the terminal
(only 3-wire connection possible).
•For the 4–20 mA operating mode, please remove the
built-in 500 Ωresistor between terminals 2 and 3.
0 VDC
Sensor Unit
MC2-X-XXXX
123
+24 V
4-20mA
/ 2-10V
ooo

User Manual - PolyGard®2 / µGard®2
Sensor for Freon Gases and Refrigerants
Page 5
PolyGard/ µGard® are registered trademarks of MSR Made in Germany GA_SC2_MC2_Freon_D_0321
Phone [phone] Specification subject to change without notice
MSR-Electronic GmbH, Buergermeister-Schoenbauer-Str. 13, D 94060 Pocking www.msr-electronic.de
4Commissioning
Only trained technicians should perform the following when commissioning:
•Check for correct mounting location.
•Check if connection is correct.
•Check power voltage (for MC2).
•Install the Sensor Cartridge(s), if not already installed ex works.
•Check Sensor Cartridge connector for correct engagement.
•Calibrate (if not already factory-calibrated).
Within the first weeks after commissioning, there may be a deviation in the sensor behaviour.
Required instruments for commissioning (calibration):
•Service-Tool STL06 or
•PCE06 Software incl. USB/RS-485 communication set:
•Calibration
▪Test gas bottle with test gas in the range of 30–70 % of the measuring range. Rest synthetic air.
▪Extraction set consisting of gas pressure regulator and flow meter.
▪Calibration adapter with tube. type C2Z4.
4.1 Installation of Sensor Cartridge
The Sensor Cartridge is supplied in a separate package and should be installed on the housing only during
commissioning to protect it against dirt and damage.
•Check gas type, range and calibration date of Sensor Cartridge.
•Define installation place on the housing of the basic or remote sensor and break out knockouts.
•Tighten the Sensor Cartridge with M32 hexagon lock nut.
•Plug in the Sensor Cartridge at X2 or X3 of the PCB. Observe plug polarity, the plug must engage.
4.2 Registration of the Sensor Cartridge
Registration and addressing of the field bus address can be read in the User Manual for sensor boards.
5Calibration
The service tool STL06 or PCE06 software are available for convenient on-site calibration. See description of
Service Tool STL06 or PCE06 Software.
There is also the possibility to exchange the SC against a calibrated SC on site. The used SC can then be
calibrated directly in the office or at the MSR_E Calibration Service and then reused.
Prior to calibration the Sensor Cartridge must be supplied with power voltage without
interruption for warm-up and stabilization. The warm-up time depends on the sensor element
and is shown in the following table:
Sensor Cartridge
Running-in time
for calibration* (h)
Stabilization time
to spec (min)
Warm-up
time (s)
Flow rate
(ml/min)
All Freon gases
6
60
300
150
Table Calibration * A running-in time of 168 h is recommended for initial commissioning.
Please observe proper handling procedures for compressed gas and test gas bottles (regulations
TRGS 220)!
Test gas can be toxic, so never inhale it!
Symptoms: Dizziness, headache and nausea.
Procedure if exposed: Remove victim to fresh air, seek medical attention.

User Manual - PolyGard®2 / µGard®2
Sensor for Freon Gases and Refrigerants
Page 6
PolyGard/ µGard® are registered trademarks of MSR Made in Germany GA_SC2_MC2_Freon_D_0321
Phone [phone] Specification subject to change without notice
MSR-Electronic GmbH, Buergermeister-Schoenbauer-Str. 13, D 94060 Pocking www.msr-electronic.de
5.1 Calibration Work
Prior to calibration you have to activate the mode “Special Mode” at the basic device, only then the
calibration menu is enabled. During the special mode the basic device doesn’t issue alerts.
•Connect calibration adapter carefully to the sensor cartridge.
•Connect calibration tool you want to use to the PCB.
•Select the Sensor Cartridge to be calibrated by selecting the gas type.
5.1.1 Procedure for Calibration with Tool or Display
•Open the calibration mode in the dialog.
•Wait until warm-up time has run out (300 s).
Zero-point calibration with tool or display:
•Open zero calibration dialog.
•Perform zero-point calibration (Display →Calculate →Save
Gain calibration with tool or display:
•Open the test gas dialog and enter the concentration of the test gas used (1000 ppm / 25 % LEL).
•Open the gain calibration dialog.
•Apply the test gas. Concentration 1000 ppm / 25 % LEL, pressure 1000 hPa (1000 mbar) ± 10%,
flow rate 150 ml/min
•Perform gain calibration.
•Save the new values after successful gain calibration.
If the set test gas has not been reached in the display, an extended calibration must be carried out.
5.1.2 Extended Calibration
Extended zero calibration
•Apply the test gas with 1000 ppm / 25 % LEL. Pressure 1000 hPa (1000 mbar) ± 10 %, flow rate 150
ml/min
•The processor input voltage must be measured against ground (gas-dependent) at the pin led out.
•Set the voltage to 1650 mV using the potentiometer.
•Stop and remove gassing and wait until the sensor has stabilized (wait at least 6 hours - stable zero
point).
•Open zero calibration dialog.
•Perform zero-point calibration (Display →Calculate →Save)
Extended gain calibration:
•Open the test gas dialog and enter the concentration of the test gas used (1000 ppm / 25 % LEL).
•Open the gain calibration dialog.
•Apply the test gas. Concentration 1000 ppm / 25 % LEL, pressure 1000 hPa (1000 mbar) ± 10%,
flow rate 150 ml/min
•Perform gain calibration.
•Save the new values after successful gain calibration.
It is required to document the successful calibration with a protocol and to attach a label to the detector
containing the date for the next calibration.
For more information, see the user manual of the corresponding tool.

User Manual - PolyGard®2 / µGard®2
Sensor for Freon Gases and Refrigerants
Page 7
PolyGard/ µGard® are registered trademarks of MSR Made in Germany GA_SC2_MC2_Freon_D_0321
Phone [phone] Specification subject to change without notice
MSR-Electronic GmbH, Buergermeister-Schoenbauer-Str. 13, D 94060 Pocking www.msr-electronic.de
5.2 Exchange of Sensor Cartridge
Instead of the on-site calibration, the used SC can be replaced simply and conveniently by a calibrated one.
The communication of the local bus (Sensor Cartridge <> PCB) is continuously monitored during
operation and results in an immediate error message on the gas controller in case of fault or
interruption. When replacing the sensor unit, the communication of the local bus is interrupted
when unplugging the SC connector which leads to an immediate triggering of the error
message.
•Disconnect the SC connector from the PCB or the remote PCB (error message will be activated).
•Loosen the locknut.
•Remove used SC.
•Take calibrated SC out of the original packaging, check for gas type, measuring range and valid
calibration date.
•Insert the SC and retighten with lock nut.
•Insert the SC plug into the socket at the PCB or the remote PCB. Check plug for proper engagement.
The local bus communication is automatically established and tested. At the same time, the gas type and the
measuring range of the "new" SC are compared with the data stored in the PCB. If they match and the
communication is correct, the error message will be automatically acknowledged in the Gas Controller.
The yellow LED of the PCB flashes with a pulse of 1 sec. if the SC connector is disconnected (communication
error). After the local bus communication has been re-established and the conformity test has been
successful, the LED goes into flashing mode with 3 sec. pulse duration until the sensor’s warm-up time is
over.
Apply a defined gas concentration on sensor element with the help of the gas generator and check the
measurement signal at the analog output or at the relay outputs.
With this test, the complete function chain “Sensor Element > Sensor Cartridge> Local Bus> PCB > Field Bus>
GC Controller” is tested.
6Inspection and Service
Inspection, service and calibration of the sensor should be done by trained technicians at regular intervals.
We therefore recommend concluding a service contract with MSR or one of their authorized partners.
According to EN 45544-4, inspection and service have to be executed at regular intervals. The maximum
intervals have to be determined and respected by the person responsible for the gas warning system
according to the legal requirements. MSR-E recommends employing the common inspection and service
intervals as specified in the general regulations of the gas measuring technique. The inspection interval
normally is 12 months.
Inspections and services must be documented. The date for the next maintenance has to be affixed to the
sensor.
6.1 Inspection
Gas sensors should be controlled regularly by a competent person according to EN 45544-4. The following
has to be checked in particular:
•Maintenance/ calibration interval not exceeded.
•Visual inspection of the sensor including cable for damage etc.
•Remove dust deposits. especially at the gas inlet.
•The filter at the gas inlet has to be replaced if extremely dirty.

User Manual - PolyGard®2 / µGard®2
Sensor for Freon Gases and Refrigerants
Page 8
PolyGard/ µGard® are registered trademarks of MSR Made in Germany GA_SC2_MC2_Freon_D_0321
Phone [phone] Specification subject to change without notice
MSR-Electronic GmbH, Buergermeister-Schoenbauer-Str. 13, D 94060 Pocking www.msr-electronic.de
6.2 Service and Calibration
When performing the maintenance, you must do the calibration and the functional test, see chapter 5, in
addition to the inspection. A fixed calibration interval is stored for each sensor type.
SC2 Sensor heads:
If this interval is exceeded, a digital maintenance message is generated and forwarded.
Performing the calibration automatically deletes this message.
MC2 Sensor heads:
If this interval is exceeded, the current output of the MC2 goes to a fixed 19 mA signal. For new devices
(factory calibration), the interval may be exceeded by a factor of 1.5.
After voltage recovery, there is a defined interruption of this message. This can be of use in order to employ
the device without the maintenance message for a few days (adjustable in system parameters -> error time,
value range > 0) until the recalibration is performed. With MC2 sensor head software version 1.02.11 and
higher (can be read out under Operating data -> Software version), this function is switched off ex works
(System parameters -> Error time, value range = 0).
Performing the calibration automatically deletes this message.
7Troubleshooting
7.1 Indicators at the SC2
The SC2 has got no diagnostic indications; they are only available on the PCB of SB2, MSC2, MSB2 or WSB2.
7.2 Indicators at the MC2
The 4–20 mA output of the MC2 can be used as diagnostic indicators.
Output current
Restart: 1 mA
Device error: 2 mA
Tolerable negative sensor drift: 3–4 mA
Normal measurement mode: 4–20 mA
Tolerable overrange: 20–21 mA
Overrange error: > 21 mA
Maintenance message: 19 mA
7.3 Sensor Board (PCB)
Trouble
Cause
Solution
Green LED isn’t on.
Power voltage not applied.
Measure tension at X4:
(16-28 V DC) Pin 1 (+) and 2 (-)
Polarity not correct at X4.
Connect correctly.
Connector X4 not plugged in.
Check the plug.
Wire breakage
Check the wiring.
Green LED doesn’t flash.
PCB: no address
Check PCB address, address correctly.
PCB: no field bus communication
Check field bus wiring, topology and
termination.
No measured value at the
Tool or Controller
SC not or wrongly plugged in.
Check SC plug.
SC not registered.
Register SC.
SC gas type/measuring range
doesn’t match with registered ones.
Check SC data<> registration data for
conformity.
Message at the Tool /
Controller:
- 24 V DC voltage <range>
- 5 V DC voltage <range>
- Temp. <range>
- WatchDog triggered
Internal error
Replace PCB.

User Manual - PolyGard®2 / µGard®2
Sensor for Freon Gases and Refrigerants
Page 9
PolyGard/ µGard® are registered trademarks of MSR Made in Germany GA_SC2_MC2_Freon_D_0321
Phone [phone] Specification subject to change without notice
MSR-Electronic GmbH, Buergermeister-Schoenbauer-Str. 13, D 94060 Pocking www.msr-electronic.de
7.4 Sensor Cartridge (Messages at the Tool / Controller)
Measuring signal <range>
Internal error
Replace SC.
5 V DC voltage < range >
Temp. < range >
WatchDog triggered
SC Input 1 stored type
Wrong SC type at input 1
Check SC at input 1, replace it.
SC Input 2 stored type
Wrong SC type at input 2
Check SC at input 2, replace it.
SC Input 3 stored type
Wrong SC type at input 3
Check SC at input 3, replace it.
8Technical Data
All specifications were collected under optimal test conditions.
We confirm compliance with the minimum requirements of the applicable standard.
8.1 MC2
ELECTRICAL
Power supply
16–29 V DC, reverse-polarity protection;
18–27 V AC (only for output signal 2–10 V)
Power consumption
65 mA, max. (1.6 VA for 24 V)
Analog output signal
Proportional, overload and short-circuit proof,
load 500 Ω for current signal, ≥ 50 kΩ for voltage signal
4–20 mA or 2–10 V = measuring range
3.2–4 mA or 1.6–2 V = underrange
> 20–21.2 mA or 10–10.6 V = overrange
2 mA or 1 V = fault
> 21.8 mA or 10.9 V = fault High
PHYSICAL
Enclosure P (M25)
Polycarbonate UL 94 V2
Colour
RAL 7032 (light grey)
Dimensions
(D x H) 24 x 22 mm (0.94 x 0.87 in.)
Weight
Ca. 30 g (0.066 lb)
Protection class
IP65 (only if mounted in housing type A, D or N)
Mounting
Screw mounting / M25
Wire connection
Screw-type terminal min. 0.25 mm2, max. 1.3 mm2,3-pin
REGULATIONS
Directives
EMC directives 2014/30/EU,
CE
Compliance with:
EN 378
EN 14624
EN 45544-1
EN 61508-1-3
EN 61010-1:2010
ANSI/UL 61010-1
CAN/CSA-C22.2 No. 61010-1
Warranty
1 year on sensor (not if poisoned or overloaded),
2 years on device

User Manual - PolyGard®2 / µGard®2
Sensor for Freon Gases and Refrigerants
Page 10
PolyGard/ µGard® are registered trademarks of MSR Made in Germany GA_SC2_MC2_Freon_D_0321
Phone [phone] Specification subject to change without notice
MSR-Electronic GmbH, Buergermeister-Schoenbauer-Str. 13, D 94060 Pocking www.msr-electronic.de
8.2 Sensor Cartridge (SC2)
ELECTRICAL
Power supply
5 V DC from Sensor Board (e.g. SB2/MSB2),
reverse polarity protected
Power consumption
160 mA, max. (0.8 VA)
Serial interface local bus
1-wire / 19200 Baud
PHYSICAL
Housing in plastic
Polycarbonate
Combustion
UL 94 V2
Housing colour
RAL 7032 (light grey)
Dimensions: Housing type P
Housing type L
(D x H) 24 x 22 mm (0.94 x 0.87 in.)
(D x H) 24 x 30 mm (0.94 x 1.18 in.)
Weight
Ca. 30 g (0.07 lb)
Protection class
IP65
Mounting
Screw mounting
Connection type
3-pin connector
Cable length
Ca. 150 mm (5.91 in.) standard version w/o cable extension
REGULATIONS
Directives
EMC Directives 2014/30/EU
CE
Conformity to:
EN 378
EN 14624
EN 45544-1
EN 61508-1-3
EN 61010-1:2010
ANSI/UL 61010-1
CAN/CSA-C22.2 No. 61010-1
Warranty
1 year on sensor (not if poisoned or overloaded),
2 years on device
8.3 Sensor Element
SENSOR ELEMENT
Gas type
See Ordering Information
Sensor element
Semiconductor sensor
FR02–FR08
%LFL
Measuring range
20–2000 ppm
0–50 % LEL
Response time
t90 ≤ 150 s (R134a)
t90 ≤ 150 s
Repeatability
± 20 %
Oxygen concentration
21 % (standard) 18 % minimum level
Temperature range
-30 °C to +60 °C (-22 to 140 °F)
Humidity range
15–90 % RH not condensing
Pressure range
Atmospheric ± 10 %
Sensor lifetime1
> 5 years / normal environment
Calibration interval
12 months
Storage temperature range
0 °C to +50 °C (32 °F to 122 °F)
Storage time
Max. 12 months
Recommended mounting height
Depending on gas type
Poisoning
The sensitivity of semiconductor sensors can be affected by
substances containing silicone and they may even lead to the
complete poisoning. The sensors are also susceptible to poisoning
by organic solvents.
1Expected lifetime under normal ambient conditions