Optris CTratio 1M, CTratio 2M Operating Manual

optris

®

CTratio

1M/ 2M

Fiber Optics Ratio Thermometer

Operator‘s Manual

Optris GmbH

Ferdinand-Buisson-Str. 14
13127 Berlin
Germany

Tel.: [phone]
Fax: [phone]

E-mail: [e-mail]
Internet: www.optris.global

Table of Contents 3-

Table of Contents

Table of Contents ............................................................................................................................................. 3

1 General Information ................................................................................................................................. 7

1.1 Description ....................................................................................................................................... 7

1.2 Warranty ........................................................................................................................................... 9

1.3 Scope of Supply ............................................................................................................................... 9

1.4 Maintenance ................................................................................................................................... 10

1.5 Safety Note ..................................................................................................................................... 10

1.6 Cautions ......................................................................................................................................... 10

1.7 Factory Default Settings ................................................................................................................. 11

2 Technical Data ........................................................................................................................................ 13

2.1 General Specifications ................................................................................................................... 13

2.2 Electrical Specifications .................................................................................................................. 14

2.3 Measurement Specifications [1M models] ..................................................................................... 15

-4 -

2.4 Measurement Specifications [2M models] ..................................................................................... 16

2.5 Optics ............................................................................................................................................. 17

3 Mechanical Installation .......................................................................................................................... 20

3.1 Accessories .................................................................................................................................... 23

3.2 Laser Sighting ................................................................................................................................ 25

4 Electrical Installation ............................................................................................................................. 26

4.1 Cable Connections ......................................................................................................................... 26

4.2 Ground Connection ........................................................................................................................ 28

5 Outputs and Inputs ................................................................................................................................ 29

5.1 Analog Output ................................................................................................................................ 29

5.2 I/O pins ........................................................................................................................................... 30

5.3 Programming Interface ................................................................................................................... 31

5.4 Relay Outputs ................................................................................................................................. 32

5.5 Alarms ............................................................................................................................................ 33

Table of Contents 5-

6 Operating ................................................................................................................................................ 34

6.1 Sensor Setup .................................................................................................................................. 34

7 IRmobile app ........................................................................................................................................... 38

8 Software Ratio Connect ........................................................................................................................ 40

8.1 Installation ...................................................................................................................................... 40

8.2 Communication Settings ................................................................................................................ 42

8.2.1 Serial Interface ........................................................................................................................... 42

8.2.2 Protocol ...................................................................................................................................... 42

9 Basics of Infrared Thermometry........................................................................................................... 43

9.1 The Ratio Principle ......................................................................................................................... 44

10 Emissivity ............................................................................................................................................... 46

10.1 Definition......................................................................................................................................... 46

10.2 Determination of unknown Emissivity ............................................................................................ 46

10.3 Characteristic Emissivity ................................................................................................................ 47

-6 -

10.4 Characteristic Slope Values ........................................................................................................... 48

10.5 Determination of unknown Slope values ........................................................................................ 48

10.6 Attenuation ..................................................................................................................................... 48

Appendix A – Emissivity Table Metals ......................................................................................................... 50

Appendix B – Emissivity Table Non Metals ................................................................................................. 52

Appendix C – Smart Averaging ..................................................................................................................... 53

Appendix D – Declaration of Conformity ..................................................................................................... 54

General Information 7-

1 General Information

1.1 Description

Thank you for choosing the optris® CTratio infrared thermometer.
The sensors of the optris CTratio series are noncontact infrared temperature sensors.
They calculate the surface temperature based on the emitted infrared energy of objects. The CTratio can
work in the 1-color-mode as well as in the ratio- or 2-color-mode [►9 Basics of Infrared Thermometry].
The optical sensing head of the CTratio is made of stainless steel (IP65/ NEMA-4 rating) and is connected
via a rugged fiber optics, which is protected by a stainless steel armour, with the sensor electronics (die
casting zinc box).

1-color-mode [1C]

The 1-color-mode is best for measuring the temperature of objects in areas where no sighting obstructions
(solid, gases or dust) exist. The measurement object must fill completely the measurement spot, if the 1­color-mode is used.

2-color-mode [2C]

In this mode the object temperature will be determined from the ratio of the signal of two separate and
overlapping infrared bands. The 2-color-mode is best for measuring the temperature of objects which are
partially obscured by other objects, openings or viewing windows that reduce energy and by dirt, smoke or
steam in the atmosphere. Another benefit of the 2-color-mode is that the measurement object can be smaller
than the measurement spot, provided the background is cooler than the target [►9.1 The Ratio Principle].

-8 -

The CTratio sensing head is a sensitive optical system. Please use only the thread for
mechanical installation.

 Avoid abrupt changes of the ambient temperature.
 Avoid mechanical violence on the head – this may destroy the system (expiry of warranty).

 If you have any problems or questions, please contact our service department.

Read the manual carefully before the initial start-up. The producer reserves the right to change
the herein described specifications in case of technical advance of the product.

► All accessories can be ordered according to the referred part numbers in brackets [ ].

General Information 9-

1.2 Warranty

Each single product passes through a quality process. Nevertheless, if failures occur please contact the
customer service at once. The warranty period covers 24 months starting on the delivery date. After the
warranty is expired the manufacturer guarantees additional 6 months warranty for all repaired or substituted
product components. Warranty does not apply to damages, which result from misuse or neglect. The
warranty also expires if you open the product. The manufacturer is not liable for consequential damage or in
case of a non-intended use of the product.
If a failure occurs during the warranty period the product will be replaced, calibrated or repaired without
further charges. The freight costs will be paid by the sender. The manufacturer reserves the right to
exchange components of the product instead of repairing it. If the failure results from misuse or neglect the
user has to pay for the repair. In that case you may ask for a cost estimate beforehand.

1.3 Scope of Supply

 CTratio sensing head with fibre connection cable and electronic box
 USB cable (Micro-USB, USB-C and USB-A cable included)
 1 mounting nut
 Mounting bracket, adjustable in one axis
 Operator’s Manual

-10 -

Never use cleaning compounds which contain solvents (neither for the lens nor for the housing).

The CTratio is equipped with an integrated laser that serves to align the optics
with the target.

►3.2 Laser Sighting

1.4 Maintenance

Lens cleaning: Blow off loose particles using clean compressed air. The lens surface can be cleaned with a

soft, humid tissue (moistened with water) or a lens cleaner (e.g. Purosol or B+W Lens Cleaner).

1.5 Safety Note

1.6 Cautions

Avoid static electricity. The fiber optical cable has a minimum bending radius of 40 mm.
In case of problems or questions which may arise when you use the CTratio, please contact our service
department.
Read the manual carefully before the initial start-up. The producer reserves the right to change the herein
described specifications in case of technical advance of the product.

General Information 11-

Output 1

Analog: TProc/ max. temperature range (according to model) = 4-20 mA

Output 2

Analog: Attenuation/ 0-100 % = 0-20 mA

Emissivity

1,000

Slope

1,000

Averaging (AVG)

0,02 s

Smart Averaging

inactive

Hold mode (Peak/Valley hold)

inactive

1ML

1MH

1MH1

2ML

2MH

2MH1

Lower limit temperature range [°C]

525

700

1000

275

400

550

Upper limit temperature range [°C]

1400

2000

3000

1000

1500

3000

Max. attenuation

95 %

Temperature unit

°C

Baud rate [kBaud]

115

Main Display Source

TProc

Visual Alarm Source

Attenuation

Visual Alarm

0-95 % green
>95 % red

I/O pins

No function

1.7 Factory Default Settings

The unit has the following presetting at time of delivery:

-12 -

Smart Averaging means a dynamic average adaptation at high signal edges [activation via
software only].

►Appendix C – Smart Averaging

Technical Data 13-

Sensing head

Electronic box

Environmental rating

IP65 (NEMA-4)

Ambient Temperature

-20...200 °C (optional to 315 °C)

0...50 °C (2M) / 0…60 °C (1M)

Storage temperature

-40...200 °C

-40...85 °C1)

Relative humidity

10...95%, non condensing

Material

stainless steel

die casting zinc

Dimensions

length: 40 mm, thread: M18x1

89 mm x 70 mm x 36,6 mm

Weight

210 g (incl. fiber optics 3 m)

420 g

Fiber optics

Single mode fiber, stainless steel armour

Fiber optics length

3 m (standard), 8 m, 15 m

Vibration

IEC 68-2-6: 3 G, 11 – 200 Hz, any axis

Shock

IEC 68-2-27: 50 G, 11 ms, any axis

Software

Ratio Connect / IRmobile Android app

2 Technical Data

2.1 General Specifications

1)

The functionality of the LCD display can be limited at ambient temperatures below 0 °C

-14 -

Power Supply

8–30 VDC

Power

max. 5 W

Aiming laser

520 nm, <1 mW, On/ Off via programming keys or software

Outputs/ analog

2x 0/ 4–20 mA (12 bit) / optional: 2x 0/ 4–20 mA (16 bit) isolated

Digital I/O pins

3 programmable in-/ outputs, usable as:

 Alarm output (open collector output [24 V/ 1 A])
 Digital input for triggered signal output and peak hold function

Output impedance

max. loop resistance 500 Ω (at 8-30 VDC)

Digital interface

USB (optional: RS232, RS485)

Relay outputs

2 x 60 V DC/ 42 V AC

eff

, 0,4 A; optically isolated (optional plug-in module)

2.2 Electrical Specifications

Technical Data 15-

1ML

1MH

1MH1

Temperature range (scalable)

1 color: 450...1400 °C
2 color: 525...1400 °C

1 color: 650...2000 °C
2 color: 700...2000 °C

1 color: 900…3000 °C
2 color: 1000…3000 °C

Spectral range

0,8 - 1,1 µm

Optical resolution

38:1

100:1

Vario focus

300 mm to infinity, infinitely adjustable

System accuracy

1), 2), 3)

±(0,5 % of reading +2 °C)

Repeatability

1), 2), 3)

±0,3 % of reading

Temperature resolution

0,1 K

Response time (90 % signal) 4)

1 ms…10 s

Emissivity

0,050…1,000 (adjustable via programming keys or analog input)

Slope

0,800…1,200 (adjustable via programming keys or analog input)

Signal processing

One-color-, Two-color-mode, Attenuation monitoring, Alarm, Average, Peak hold,

Valley hold, Advanced peak hold with threshold and hysteresis (adjustable via

programming keys or software)

2.3 Measurement Specifications [1M models]

1)

Measurements within specification over 5-95% of range

2)

at ambient temperature 235 °C

3)

 = 1/ Response time 1 s

4)

with dynamic adaptation at low signal levels

-16 -

2ML

2MH

2MH1

Temperature range (scalable)

1 color: 250...1000 °C
2 color: 275...1000 °C

1 color: 375...1500 °C
2 color: 400...1500 °C

1 color: 500…3000 °C
2 color: 550…3000 °C

Spectral range

1,45 - 1,75 µm

Optical resolution

38:1

50:1

100:1

Vario focus

300 mm to infinity, infinitely adjustable

System accuracy

1), 2), 3)

±(0,5 % of reading +2 °C)

Repeatability

1), 2). 3)

±0,3 % of reading

Temperature resolution

0,1 K

Response time (90 % signal) 4)

1 ms…10 s

Emissivity

0,050…1,000 (adjustable via programming keys or analog input)

Slope

0,800…1,200 (adjustable via programming keys or analog input)

Signal processing

One-color-, Two-color-mode, Attenuation monitoring, Alarm, Average, Peak hold,

Valley hold, Advanced peak hold with threshold and hysteresis (adjustable via

programming keys or software)

2.4 Measurement Specifications [2M models]

1)

Measurements within specification over 5-95% of range

2)

at ambient temperature 235 °C

3)

 = 1/ Response time 1 s

4)

with dynamic adaptation at low signal levels

Technical Data 17-

Optics

Focus adjustable in the range

SFV

300 mm till infinity

D = Distance from front of the sensing head to the object
S = Spot size

2.5 Optics

The vario optics of the CTratio allows a smooth focusing of the optics to the desired distance.

The following tables show the diameter of the measuring spot for some selected distances. The spot size
refers to 90 % of the radiation energy.
The distance is always measured from the front edge of the sensing head.

As an alternative to the optical diagrams, the spot size calculator can also be used on the Optris website
(https://www.optris.global/spot-size-calculator) or via the Optris calculator app. The app can be downloaded
for free from the Google Play Store (see QR code).

-18 -

1ML / 2ML (D:S=38:1)

Spot size

mm

7,9

13,2

19,7

26,3

39,5

52,6

65,8

131,6

Measurement distance

mm

300

500

750

1000

1500

2000

2500

5000

2MH (D:S=50:1)

Spot size

mm 6 10

15

20

30

40

50

100

Measurement distance

mm

300

500

750

1000

1500

2000

2500

5000

1MH / 1MH1 / 2MH1 (D:S=100:1)

Spot size

mm 3 5

7,5

10

15

20

25

50

Measurement distance

mm

300

500

750

1000

1500

2000

2500

5000

Technical Data 19-

Sensor placement [1C mode]

The size of the measuring object and the optical resolution of the infrared thermometer determine the
maximum distance between sensing head and measuring object. In order to prevent measuring errors the
object should fill out the field of view of the optics completely. Consequently, the spot should at all times have
at least the same size like the object or should be smaller than that.

Sensor placement [2C mode]

In the 2-color-mode the sensing head can be placed under various conditions, like:

 Measurement through holes smaller than the spot size
 Measurement through dust, smoke or steam in the atmosphere
 Measurement of objects smaller than the measurement spot
 Measurement through a dirty lens or dirty sighting window

[►9.1 The Ratio Principle]

-20 -

Please make sure that the minimum bending radius of the fiber optics of 40 mm will be
considered during installation.

3 Mechanical Installation

The CTratio sensing heads are equipped with a metrical M18x1-thread and can be installed either directly via
the sensor thread or with help of the hex nuts (1 piece included in scope of supply) to the mounting bracket
available. Various mounting brackets, which make the adjustment of the sensing head easier, can be
additionally ordered as accessories.

Sensing head

Mechanical Installation 21-

The electronic box is also available with closed cover (display and programming keys
with no access from outside) [ACCTCOV].

Electronic box

-22 -
The CTratio pyrometer is equipped with a vario optics. This enables you to focus the device from a distance

of 300 mm to infinity. To focus the sensor, loosen the knurled screw (1) on the head. Now you can focus the
device on the head (2). After alignment, retighten the knurled screw. This secures the focus.

By turning the rotary button clockwise you will change the focus in direction far. By turning
counterclockwise you will change the focus in direction close.

Sensing head – Focusing the unit

Mechanical Installation 23-

Mounting bracket, adjustable in one axis
[ACCTFBMH]

Air purge collar [ACCTAPMH]

The needed amount of air (approx. 2...10 l/ min.) depends on the application and the installation
conditions on-site.

3.1 Accessories

The lens must be kept clean at all times from dust, smoke, fumes and other contaminants in order to avoid
reading errors (in the 1-color-mode). These effects can be reduced by using an air purge collar. Make sure to
use oil-free, technically clean air, only.

-24 -

ACCTRAIL

Rail Mount Adapter for Electronic box

With the rail mount adapter the CTratio electronics can be mounted easily on a DIN rail (TS35) according
EN50022.

Mechanical Installation 25-

The integrated laser sighting supports the alignment and focusing of the optics. The
size of the laser dot is equal to the real measurement spot size at any distance.

The laser can be activated/ deactivated via the programming keys on the unit or via
the software. If the laser is activated a yellow LED will shine (beside temperature
display).

[►4 Electrical Installation, 6 Operating]
At ambient temperatures >50 °C inside the electronic box the laser will switch

off automatically.

 Do not point the laser directly at the eyes of persons or animals! Do not stare into the

laser beam. Avoid indirect exposure via reflective surfaces!

 The laser is not suitable for continuous operation.

3.2 Laser Sighting

Before you open the box, remove the fiber optical cable from the electronics or disassemble the
optical head the sensor must be switched off and disconnected from the power supply and USB
interface!

-26 -

The supplied USB cable can be connected to the side of the electronics box.
The device can be operated directly via the Ratio Connect software or the
IRmobile App.
For the electrical installation of further interfaces and when using the in­/outputs please open at first the cover of the electronic box (4 screws). Below
the display are the screw terminals for the cable connection.

+8..30 VDC

Power supply

Opened electronic box with terminal connections

GND

Ground (0 V) of power supply

GND

Ground (0 V) of in- and outputs

I/O 1

I/O pin 1 (digital In-/ Output or analog input)

I/O 2

I/O pin 2 (digital In-/ Output or analog input)

I/O 3

I/O pin 3 (digital In-/ Output or analog input)

COM

Ground of OUT

OUT 1

Analog current output 1

OUT 2

Analog current output 2

4 Electrical Installation

4.1 Cable Connections

Designation

Electrical Installation 27-

Please do never connect a supply voltage to the analog outputs as this will destroy the
output!
The CTratio is not a 2-wire sensor!

Power supply

Please use a power supply unit with an output voltage of 8–30 VDC with a power of 5 W. The ripple should
be max. 200 mV. Please use shielded cables only for all power and data lines.
The sensor shield has to be grounded.

Cable Assembling

The cable gland M12x1,5 allows the use of cables with a diameter of 3 to 5 mm.
Remove the isolation from the cable (40 mm power supply, 50 mm signal outputs, 60 mm functional inputs).
Cut the shield down to approximately 5 mm and spread the strands out. Extract about 4 mm of the wire
isolation and tin the wire ends.
Place the pressing screw, the rubber washer and the metal washers of the cable gland one after the other
onto the prepared cable end. Spread the strands and fix the shield between two of the metal washers. Insert
the cable into the cable gland until the limit stop. Screw the cap tight.
Every single wire may be connected to the according screw clamps according to their colors.

-28 -

Use shielded cables only. The sensor shield has to be grounded.

4.2 Ground Connection

On the mainboard PCB you will find a black wire which is connecting factory-default the ground connections
(GND power supply/ outputs) with the ground of the electronics housing.

Removing the ground connection is not recommended.

Outputs and Inputs 29-

Please do never connect a supply voltage to the analog outputs as this will destroy the output.

The CTratio is not a 2-wire sensor!

TProc

Process temperature

TRatio

Ratio temperature

T1

1C temperature

T2

2C temperature

Attenuation

Signal attenuation in %

TDet

Detector temperature

TBox

Box temperature

5 Outputs and Inputs

The CTratio has two analog output and three digital I/O pins (programmable as in- or output).

5.1 Analog Output

The selection of the signal on output channel 1 and 2 (0/4-20 mA) can be done via the software Ratio
Connect [►8 Software Ratio Connect] or the IRmobile app [►7 IRmobile app].

The following signal sources can be selected for output channel 1 and 2:

-30 -

Function

I/O pin acts as

Description

Digital Alarm

output digital

Open collector output/ definition as HIGH- or LOW alarm via
norm. open/ norm. close options in software dialog.

Valid LO

input digital

The output follows the object temperature as long as there is
a Low level at the I/O pin. After discontinuation of the Low
level the last value will be held.

Valid HI

input digital

The output follows the object temperature as long as there is
a High level at the I/O pin. After discontinuation of the High
level the last value will be held.

Hold ‗/¯

input digital

The last value will be held if there is a signal with a rising
edge on the I/O pin.

Hold ¯\‗

input digital

The last value will be held if there is a signal with a falling
edge on the I/O pin.

Hold Reset LO

input digital

Reset of Peak or valley hold (HI-LO signal)

Hold Reset HI

input digital

Reset of Peak or valley hold (LO-HI signal)

Slope external

input analog

The slope value can be adjusted via a 0-10 V signal on the
I/O pin (scaling possible via software).

Emiss. external

input analog

The emissivity value can be adjusted via a 0-10 V signal on
the I/O pin (scaling possible via software).

High-level:

Via software

Low-level:

Via software

5.2 I/O pins

The CTratio has three digital pins which can be programmed as outputs (digital) or as inputs (digital or
analog) using the Ratio Connect software. The following functions are available:

Outputs and Inputs 31-

The CTratio has on the side of the electronic box a
USB interface for programming and running the
sensor. The USB cable is included in the scope of
supply. As an option, the device can also be
equipped with an RS232 or RS485 interface.

If you want to install the optionally available interfaces, plug the interface board into the place provided,
which is located beside the display. In the correct position the holes of the interface match with the thread
holes of the electronic box. Now press the board down to connect it and use both M3x5 screws for fixing it.
Plug the preassembled interface cable with the terminal block into the male connector of the interface board.

When using the current outputs, an external power supply (8-30 V) is recommended, since the
maximum power consumption is 5 W.

5.3 Programming Interface

-32 -

The switching thresholds are in accordance with the values for the visual alarms (LCD backlight).
To set the alarm values the digital programming interface (USB) and the software is needed.

5.4 Relay Outputs

The CTratio can be optionally equipped with a relay output. The relay board will be installed the same way as
the programming interface.

The relay board provides two fully isolated switches, which have the capability to switch
max. 60 VDC/ 42 VAC

, 0,4 A DC/AC. A red LED shows the closed switch.

RMS

Outputs and Inputs 33-

The CTratio has the following Alarm
features:

For a setup of the alarm values, selection of the signal sources and definition as high or low
alarm (via change of normally open/ closed) the programming interface (USB) including the
software is needed.

All alarms have a fixed hysteresis of 2 K.

5.5 Alarms

Visual Alarms

These alarms will cause a change of the color of the LCD display.

Digital Alarm 1, 2, 3

All the I/O pins can be programmed as alarm output. In this case the pin acts as an open collector output
(24 V/ 1 A).

The following signal sources can be selected:

TProc/ TRatio/ T1/ T2/ Attenuation/ TDet/ TBox

Different wirings of the open collector output

-34 -

Factory Default Setting

To set the CT back to the factory default settings, please press at
first the Down-key and then the Mode-key and keep both pressed
for approx. 3 seconds.
The display will show RESET for confirmation.

Pressing the Mode button again recalls the last called function on
the display. The signal processing features Peak hold and Valley

hold cannot be selected simultaneously.

6 Operating

After power up the unit the sensor starts an initializing routine for some seconds. During this time the display
will show INIT. After this procedure the process temperature is shown in the display. The display backlight
color changes according to the alarm settings [►5.5 Alarms].

6.1 Sensor Setup

The programming keys Mode, Up and Down enable the user to set the sensor on-site. The current
measuring value or the chosen feature is displayed. With Mode the operator obtains the chosen feature, with

Up and Down the functional parameters can be selected – a change of parameters will have immediate
effect. If no key is pressed for more than 10 seconds the display automatically shows the calculated object

temperature (according to the signal processing).

Operating 35-

Display

Mode [Sample]

Adjustment Range

S OFF

Laser Sighting

ON/ OFF

T RAT 878.9

Ratio temperature after signal processing) [878,9 °C]

fixed

T1 897,1

1 channel temperature [879,1 °C]

fixed

T2 879,0

2 channel temperature [879,0 °C]

fixed

ATT 0.0

Attenuation[0,0 %]

fixed

T DET 50.1

Detector temperature [50,1 °C]

fixed

T BOX 38.6

Electronic box temperature [38,6 °C]

fixed

SLOPE 0.993

Emissivity ratio [0,993]

0,8…1,2

EMISS 1.000

Emissivity [1,000]

0,050 … 1,100

AVG 0.020

Signal output Average [0,020 s]

AVG 0.000 = inactive/ 0,1 … 999,9 s

MAX A 80.0

Maximum Attenuation

0,1 … 99 %

HOLD

H TIM
H TH
H HY

OFF
PEAK/ VALL

APEAK/ AVALL
APEAK/ AVALL

OFF/ PEAK/ VALL/ APEAK/ AVALL

0…65 s (65 = infinity)

Starting temperature…end temperature
Hysteresis setting in °C/°F

U °C

Temperature unit [°C]

°C/ °F

M 01

Multidrop address [1] (only with RS485 interface)
RS422 mode

01 … 32
RS422 (Press Down button on M01)

BAUD 115.2K

Baud rate in kBaud [115.2K]

115.2 / 921.6 kBaud

-36 -

S OFF

Activating (ON) and Deactivating (OFF) of the Sighting Laser. By pressing Up or Down
the laser can be switched on and off.

SLOPE

The Slope is the quotient of the emissivity’s of both of the overlapping wavelengths and
therewith the deciding parameter for measurements in 2-color-mode.

EMISS 1.000

Setup of Emissivity. Pressing Up increases the value, Down decreases the value (also
valid for all further functions). The emissivity is a material constant factor to describe the
ability of the body to emit infrared energy [►10 Emissivity].

AVG 0.020

Setup of Average time. In this mode an arithmetic algorithm will be performed to
smoothen the signal. The set time is the time constant. This function can be combined
with all other post processing functions. The shortest value is 0,001 s. If the value is set to

0.0 the function is deactivated.

HOLD

Setup of signal processing. By pressing Up or Down the mode can be selected.
PEAK: Setup of Peak hold. In this mode the sensor is waiting for descending signals. If

the signal descends the algorithm maintains the previous signal peak for the specified
time.
After the hold time the signal will drop down to the second highest value or will descend
by 1/8 of the difference between the previous peak and the minimum value during the
hold time. This value will be held again for the specified time. After this the signal will drop
down with slow time constant and will follow the current object temperature.
If the value is set to 0.0 the display will show --- (function deactivated).

VALL: Setup of Valley hold. In this mode the sensor waits for ascending signals. The
definition of the algorithm is according to the peak hold algorithm (inverted).
If the value is set to 0.0 the function deactivated.

APEAK (Advanced Peak Hold): In this mode the sensor waits for local peak values. Peak

Operating 37-

values which are lower than their predecessors will only be taken over if the temperature
has fallen below the Threshold value beforehand. If Hysteresis is activated a peak in
addition must decrease by the value of the hysteresis before the algorithm takes it as a
new peak value.

AVALL (Advanced Valley Hold): This mode is the inverted function of Advanced Peak
hold. The sensor waits for local minima. Minimum values which are higher than their
predecessors will only be taken over if the temperature has exceeded the Threshold
value beforehand. If Hysteresis is activated a minima in addition must increase by the
value of the hysteresis before the algorithm takes it as a new minimum value.

U °C

Setup of the Temperature unit [°C or °F].

M 01

Setup of the Multidrop address. In a RS485 network each sensor will need a specific
address. This menu item will only be shown if a RS485 interface board is plugged in. For
using the RS422 mode, press once the down button on M01.

BAUD 115.2K

Setup of the Baud rate for digital data transfer.

-38 -

7 IRmobile app

The CTratio sensor has a direct connection to an Android smartphone or tablet. All you
have to do is download the IRmobile app for free in the Google Play store. This can also be
done via the QR code. The supplied USB cables can be used for connection to the device.

With IRmobile you are able to monitor and analyse your infrared temperature measurement on a connected
smartphone or tablet. This app works on most Android devices running 5.0 or higher with a micro USB or
USB-C port supporting USB-OTG (On The Go). It is easy to operate: after you plug your CTratio device to
your phone or tablet, the app will start automatically. The device is powered by your phone. Different digital
temperature values can be displayed in the temperature time diagram. You can easily zoom-in the diagram
to see more details and small signal changes.

IRmobile app 39-

IRmobile app features:

 Temperature time diagram with zoom function
 Digital temperature values
 Setup of emissivity, transmissivity and other parameters
 Scaling of the analog output and setting of the alarm output
 Change of temperature unit: Celsius or Fahrenheit
 Saving/loading of configurations and T/t diagrams
 Restore factory default sensor settings
 Integrated simulator

Supported for:

 Optris pyrometers: Compact series, high performance series and video thermometers
 Optris IR cameras: PI and Xi series
 For android devices running 5.0 or higher with a micro USB or USB-C port supporting USB-OTG (On

The Go)

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Download the software from the Optris website.
Please start Setup.exe and follow the instructions of
the wizard until the installation is finished.
The software can be downloaded via the Optris website under the following link:

https://www.optris.global/downloads-software

A detailed description of the software is provided in the documentation folder.

Minimum system requirements:

 Windows 7, 8, 10
 USB interface
 Hard disc with at least 30 MByte free space
 At least 128 MByte RAM

8 Software Ratio Connect

8.1 Installation

The installation wizard will place a launch icon on the desktop and in the start menu:

[Start]\Programs\RatioConnect.

If you want to uninstall the software from your system please use the uninstall icon in the start menu.

Software Ratio Connect 41-

Main Features:

 Graphic display for temperature trends and

automatic data logging for analysis and
documentation

 Complete sensor setup and remote controlling
 Adjustment of signal processing functions
 Programming of outputs and functional inputs

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Baudrate:

115,2 / 921,6 kBaud

Data bits:

8

Parity:

none

Stop bits:

1

Flow control:

off

8.2 Communication Settings

8.2.1 Serial Interface

8.2.2 Protocol

All sensors of the CT series are using a binary protocol.

Basics of Infrared Thermometry 43-

9 Basics of Infrared Thermometry

Depending on the temperature each object emits a certain amount of infrared radiation. A change in the
temperature of the object is accompanied by a change in the intensity of the radiation. For the measurement
of “thermal radiation” infrared thermometry uses a wave-length ranging between 1 µm and 20 µm.
The intensity of the emitted radiation depends on the material. This material contingent constant is described
with the help of the emissivity which is a known value for most materials (►10 Emissivity).

Infrared thermometers are optoelectronic sensors. They calculate the surface temperature on the basis of
the emitted infrared radiation from an object. The most important feature of infrared thermometers is that
they enable the user to measure objects contactless. Consequently, these products help to measure the
temperature of inaccessible or moving objects without difficulties. Infrared thermometers basically consist of
the following components:

 lens
 spectral filter
 detector
 electronics (amplifier/ linearization/ signal processing)

The specifications of the lens decisively determine the optical path of the infrared thermometer, which is
characterized by the ratio Distance to Spot size.
The spectral filter selects the wavelength range, which is relevant for the temperature measurement. The
detector in cooperation with the processing electronics transforms the emitted infrared radiation into electrical
signals.

-44 -

►

When the field of view to the target is partially blocked or obscured.

►

When the target is smaller than the sensor’s field of view.

►

When target emissivity are low or changing by the same factor in both wavelength bands.

►

Sighting paths are partially blocked (either intermittently or permanently).

►

Dirt, smoke, or steam is in the atmosphere between the sensor and target.

►

Measurements are made through items or areas that reduce emitted energy, such as grills, screens,
channels or small openings.

9.1 The Ratio Principle

The 2-color ratio technology makes possible accurate and repeatable temperature measurements that are
free from dependence on absolute radiated energy values. In use, a 2-color sensor determines temperature
from the ratio of the radiated energies in two separate wavelength bands (colors). The benefits of 2-color
sensors are that accurate measurements can be made under the following conditions:

Another benefit is that 2-color sensors measure closer to the highest temperature within the measured spot
(spatial peak picking) instead of an average temperature. A 2-color sensor can be mounted farther away,
even if the target does not fill the resulting spot size. The convenience is that you are not forced to install the
sensor at some specific distance based upon target size and the sensor’s optical resolution.

Partially Obscured Targets

The radiated energy from a target is, in most cases, equally reduced when objects or atmospheric materials
block some portion of the optical field of view. It follows that the ratio of the energies is unaffected, and thus
the measured temperatures remain accurate.
A 2-color sensor is better than a 1-color sensor in the following conditions:

Basics of Infrared Thermometry 45-

1-color sensors see polluted atmosphere and dirty windows and lenses as a reduction in energy
and give much lower than actual temperature readings.

►

Measuring of wire or rod — often too narrow for field of view or moving or vibrating unpredictably. It is
much easier to obtain accurate results because sighting is less critical with 2-color sensors.

Targets Smaller Than Field of View

When a target is not large enough to fill the field of view, or if the target is moving within the field of view,
radiated energies are equally reduced, but the ratio of the energies is unaffected and measured
temperatures remain accurate. This remains true as long as the background temperature is much lower than
the target temperature.
Example:

Low or Changing Emissivity

If the emissivity in both wavelengths (colors) were the same, as they would be for any blackbody
(emissivity = 1.0) or greybody (emissivity < 1.0 but constant), then their ratio would be 1, and target
emissivity would not be an influence. However, in nature there is no such thing as a greybody. The emissivity
of all real objects changes with wavelength and temperature, at varying degrees, depending on the material.

When emissivity is uncertain or changing, a 2-color sensor can be more accurate than a 1-color instrument
as long as the emissivity changes by the same factor in both wavelength bands. Note, however, that
accurate measurement results are dependent on the application and the type of material being measured.
To determine how to use 2-color sensors with your application when uncertain or changing emissivity are a
factor, please contact your sales representative.

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10 Emissivity

10.1 Definition

The intensity of infrared radiation, which is emitted by each body, depends on the temperature as well as on
the radiation features of the surface material of the measuring object. The emissivity (ε – Epsilon) is used as
a material constant factor to describe the ability of the body to emit infrared energy. It can range between 0
and 100 %. A “blackbody” is the ideal radiation source with an emissivity of 1,0 whereas a mirror shows an
emissivity of 0,1.
If the emissivity chosen is too high, the infrared thermometer may display a temperature value which is much
lower than the real temperature – assuming the measuring object is warmer than its surroundings. A low
emissivity (reflective surfaces) carries the risk of inaccurate measuring results by interfering infrared radiation
emitted by background objects (flames, heating systems, chamottes). To minimize measuring errors in such
cases, the handling should be performed very carefully and the unit should be protected against reflecting
radiation sources.

10.2 Determination of unknown Emissivity

► First, determine the actual temperature of the measuring object with a thermocouple or contact sensor.

Second, measure the temperature with the infrared thermometer and modify the emissivity until the
displayed result corresponds to the actual temperature.

► If you monitor temperatures of up to 380 °C you may place a special plastic sticker (emissivity dots – part

number: ACLSED) onto the measuring object, which covers it completely. Now set the emissivity to 0,95

Emissivity 47-

and take the temperature of the sticker. Afterwards, determine the temperature of the adjacent area on
the measuring object and adjust the emissivity according to the value of the temperature of the sticker.

► Cove a part of the surface of the measuring object with a black, flat paint with an emissivity of 0,98. Adjust

the emissivity of your infrared thermometer to 0,98 and take the temperature of the colored surface.
Afterwards, determine the temperature of a directly adjacent area and modify the emissivity until the
measured value corresponds to the temperature of the colored surface.

CAUTION: On all three methods the object temperature must be different from ambient temperature.

10.3 Characteristic Emissivity

In case none of the methods mentioned above help to determine the emissivity you may use the emissivity
tables ►Appendix A – Emissivity Table Metals and Appendix B – Emissivity Table Non Metals. These
are average values, only. The actual emissivity of a material depends on the following factors:

 temperature
 measuring angle
 geometry of the surface
 thickness of the material
 constitution of the surface (polished, oxidized, rough, sandblast)
 spectral range of the measurement
 transmissivity (e.g. with thin films)

-48 -

Cobalt, Iron, Nickel, Stainless steel, Steel

► oxidized surfaces

Slope: 1,000

Cobalt, Iron (solid, molten), Molybdenum,
Nickel, Platinum, Rhodium, Stainless steel,
Steel, Tantalum, Tungsten, Wolfram

► non-oxidized surfaces

Slope: 1,060

10.4 Characteristic Slope Values

The slope is the quotient of the emissivity of both of the overlapping wavelength bands. The factory default
value for the slope is 1,000. The following slopes are typical reference values. The real slope can vary
depending on the metal alloy and surface finish.

10.5 Determination of unknown Slope values

Basically you can use the same methods to determine an unknown slope as described under
►10.2 Determination of unknown Emissivity. As the CTratio is dedicated for high temperature
applications, only the first method may be practically applicable (use of a t/c or other contact probe).

10.6 Attenuation

The CTratio is able to measure the temperature of targets smaller than the field of view (FOV). If the target
size is smaller than the FOV (and thus attenuating the signal) this may cause a small inaccuracy of the
reading. The inaccuracy is dependent on the object temperature and value of attenuation. The higher the
object temperature and attenuation the higher the inaccuracy of the sensor.

Emissivity 49-

This figure is showing the typical temperature reading of a ratio thermometer optris CTratio in both the 1­color- and the 2-color-mode in addiction of increasing contamination of the optical transmission path in­between the target and the ratio thermometer. Due to the ratio principle the 2 channel signal (upper curve)
stays very stable over a wide range of attenuation up to over 90 %. The signal of the 1 channel mode (lower
curve), acting like in a standard pyrometer with one measuring wavelength only, is decreasing rapidly with
the contamination of the transmission path.

-50 -

1,0 µm 1,6 µm 5,1 µm 8-14 µm

Aluminium non oxidized 0,1-0,2 0,02-0,2 0,02-0,2 0,02-0,1

polished 0,1-0,2 0,02-0,1 0,02-0,1 0,02-0,1
roughened 0,2-0,8 0,2-0,6 0,1-0,4 0,1-0,3
oxidized 0,4 0,4 0,2-0,4 0,2-0,4

Brass polished 0,35 0,01-0,05 0,01-0,05 0,01-0,05

roughened 0,65 0,4 0,3 0,3
oxidized 0,6 0,6 0,5 0,5

Copper polished 0,05 0,03 0,03 0,03

roughened 0,05-0,2 0,05-0,2 0,05-0,15 0,05-0,1

oxidized 0,2-0,8 0,2-0,9 0,5-0,8 0,4-0,8
Chrome 0,4 0,4 0,03-0,3 0,02-0,2
Gold 0,3 0,01-0,1 0,01-0,1 0,01-0,1
Haynes alloy 0,5-0,9 0,6-0,9 0,3-0,8 0,3-0,8
Inconel electro polished 0,2-0,5 0,25 0,15 0,15

sandblast 0,3-0,4 0,3-0,6 0,3-0,6 0,3-0,6

oxidized 0,4-0,9 0,6-0,9 0,6-0,9 0,7-0,95
Iron non oxidized 0,35 0,1-0,3 0,05-0,25 0,05-0,2

rusted 0,6-0,9 0,5-0,8 0,5-0,7

oxidized 0,7-0,9 0,5-0,9 0,6-0,9 0,5-0,9

forged, blunt 0,9 0,9 0,9 0,9

molten 0,35 0,4-0,6
Iron, casted non oxidized 0,35 0,3 0,25 0,2

oxidized 0,9 0,7-0,9 0,65-0,95 0,6-0,95

Material

typical Emissivity

Spectral response

Appendix A – Emissivity Table Metals

Appendix A – Emissivity Table Metals 51-

1,0 µm 1,6 µm 5,1 µm 8-14 µm

Lead polished 0,35 0,05-0,2 0,05-0,2 0,05-0,1

roughened 0,65 0,6 0,4 0,4

oxidized 0,3-0,7 0,2-0,7 0,2-0,6
Magnesium 0,3-0,8 0,05-0,3 0,03-0,15 0,02-0,1
Mercury 0,05-0,15 0,05-0,15 0,05-0,15
Molybdenum non oxidized 0,25-0,35 0,1-0,3 0,1-0,15 0,1

oxidized 0,5-0,9 0,4-0,9 0,3-0,7 0,2-0,6
Monel (Ni-Cu) 0,3 0,2-0,6 0,1-0,5 0,1-0,14
Nickel electrolytic 0,2-0,4 0,1-0,3 0,1-0,15 0,05-0,15

oxidized 0,8-0,9 0,4-0,7 0,3-0,6 0,2-0,5
Platinum black 0,95 0,9 0,9
Silver 0,04 0,02 0,02 0,02
Steel polished plate 0,35 0,25 0,1 0,1

rustless 0,35 0,2-0,9 0,15-0,8 0,1-0,8

heavy plate 0,5-0,7 0,4-0,6

cold-rolled 0,8-0,9 0,8-0,9 0,8-0,9 0,7-0,9

oxidized 0,8-0,9 0,8-0,9 0,7-0,9 0,7-0,9
Tin non oxidized 0,25 0,1-0,3 0,05 0,05
Titanium polished 0,5-0,75 0,3-0,5 0,1-0,3 0,05-0,2

oxidized 0,6-0,8 0,5-0,7 0,5-0,6
Wolfram polished 0,35-0,4 0,1-0,3 0,05-0,25 0,03-0,1
Zinc polished 0,5 0,05 0,03 0,02

oxidized 0,6 0,15 0,1 0,1

Spectral response

Material

typical Emissivity

-52 -

1,0 µm 2,2 µm 5,1 µm 8-14 µm

Asbestos 0,9 0,8 0,9 0,95
Asphalt 0,95 0,95
Basalt 0,7 0,7
Carbon non oxidized 0,8-0,9 0,8-0,9 0,8-0,9

graphite 0,8-0,9 0,7-0,9 0,7-0,8
Carborundum 0,95 0,9 0,9
Ceramic 0,4 0,8-0,95 0,8-0,95 0,95
Concrete 0,65 0,9 0,9 0,95
Glass plate 0,2 0,98 0,85

melt 0,4-0,9 0,9
Grit 0,95 0,95
Gypsum 0,4-0,97 0,8-0,95
Ice 0,98
Limestone 0,4-0,98 0,98
Paint non alkaline 0,9-0,95
Paper any color 0,95 0,95
Plastic >50 µm non transparent 0,95 0,95
Rubber 0,9 0,95
Sand 0,9 0,9
Snow 0,9
Soil 0,9-0,98
Textiles 0,95 0,95
Water 0,93

Wood natural 0,9-0,95 0,9-0,95

Material

typical Emissivity

Spectral response

Appendix B – Emissivity Table Non Metals

Appendix C – Smart Averaging 53-

Signal graph with Smart Averaging function

Signal graph without Smart Averaging function

Appendix C – Smart Averaging

The average function is generally used to smoothen the output signal. With the adjustable parameter time
this function can be optimal adjusted to the respective application. One disadvantage of the average function
is that fast temperature peaks which are caused by dynamic events are subjected to the same averaging
time. Therefore those peaks can only be seen with a delay on the signal output.
The function Smart Averaging eliminates this disadvantage by passing those fast events without averaging
directly through to the signal output.

-54 -

Appendix D – Declaration of Conformity

optris CTratio

-MA

-E2019

-12-A