LumaSense Technologies ISR 6 Advanced - Manual (Page 23)

ISR 6 Advanced Manual Settings / parameter descriptions · 23
The table shows typical errors that can result when the emissivity of one wavelength differs
from the other wavelength by only 1%. The errors can get quite large as temperatures increase.
This error can be much larger than a 1-color IR pyrometer would produce for 1% emissivity
change. Therefore, it is important to select the proper mode (2-color vs. 1-color) on the ISR 6 to
measure a specific material.
Another source of error is dust or smoke in the optical path which alters the transmission in one
wavelength more than the other. If the “dust” transmits 1% less energy at wavelength 1 than at
wavelength 2, the error table above also applies. Since not all smoke, dust, or dense steam
transmits equally at each wavelength, errors may become larger than expected for a 2-color
instrument. Usually the smoke and dust are the result of the material being processed and can
be cleared from the sight path by a fan or air purge tube.
In some materials, the emissivity may change at different rates with material temperature. Some
materials exhibit great changes in emissivity with temperature or time as oxidation modifies the
surface finish of the material. Such materials are not suited for measurement with 2-color
instruments. When problems are compounded with spectrally absorbing dust or smoke
(described above), obtaining reliable temperature readings with any 2-color instrument may be
impossible. In cases like this, a single color instrument using the shortest wavelength possible
would be the better choice. If this problem is encountered, switch the ISR 6 to 1-color mode. In
some situations, the single color mode will outperform the ratio mode.
4.4 Transmittance t
Transmittance is a parameter that can compensate for signal loss due to external windows etc.
For example, if the emissivity of the material is 0.6 and the transmittance of an additional
window is 0.9, then the product would be 0.54 which is well inside the allowed range.
The product of transmittance and emissivity ( t x
e
) must not be less than 20% .
Note: Transmittance t Settings: 5% to 100% in steps of 1/1000 (1-color mode)
4.5 Response Time (t
90
)
The response time t
90
is the time interval for the analog output of the pyrometer to go from a
low temperature value up to 90% of the temperature step to a high value when measuring an
abrupt increase from said low to said high temperature.
Independently of this, the pyrometer performs a measurement every 10 ms and updates the
analog output. Slower response times can be used to achieve a constant temperature reading
for measuring objects that have rapidly fluctuating temperatures.
The response time is set using the InfraWin software or by using the UPP Data Format
commands. When the setting is set to min., the ISR 6 Advanced operates using a time constant
of <2 ms (with dynamic adaption at low signal levels). The response time can be extended to
0.01 s; 0.05 s; 0.25 s; 1 s; 3 s; 10 s.
Note: Settings for Response Time t
90
: min, 0.01 s; 0.05 s; 0.25 s; 1 s; 3 s; 10 s
4.6 Clear Peak Memory (t
CLEAR
)
The integrated maximum value storage is activated when the parameter tclear is set to
something other than “OFF” or “HOLD”.