LumaSense Technologies ISR 12-LO - Handbuch (Seite 16)

IMPAC pyrometers ISR 12-LO · IGAR 12-LO
15
8.2 Special indications
Display Description
7777 warming-up time after switching on
8888 measurement exceeds the end of sub range
0 ... 999
(Intensity „relative signal“) Only type ISR 12-LO in ratio mode:
If the laser targeting light is switched on the converter shows the inten-
sity of the measuring signal in percent. No measurement will be done,
the analog output keeps the last measurement value (see also
10.8 Measurement color bar)
8000 Only model ISR 12-LO in mono mode:
laser targeting light on, no measurements will be done (analog output
keeps the last measurement value)
8.3
Factory settings
Emissivity (
ε
) = 1.000
Emissivity slope (K) = 1.000
Exposure time (t
90
/ s) = 0.00
Clear time (t
CL
) = 0.00
Operating mode (1 / 2 / M) = 2
Analog output (0 / 4 mA) = 0 ... 20 mA
Switch-off limit = 10%
Sub range (from / to) is basic temperature range
Address (Adr) = 00
Baud rate (kBaud) = 19.2 kBd
Temperature display (°C / °F) = °C
Switch for interface (RS485 / RS232) = RS232
Warning level „dirty window“ = 0% (equivalent to “off”)
9 Parameters
9.1 Emissivity
ε
/ emissivity slope K
Emissivity (
ε)
setting only in mono mode.
Emissivity slope setting (K =
ε
1 /
ε
2) only in ratio mode.
For a correct measurement it is necessary to adjust the emissivity. This emissivity is the
relationship between the emission of an real object and the emission of a black body
radiation source (this is an object which absorbs all incoming rays and has an emissivity
of 100%) at the same temperature. Different materials have different emissivities ranging
between 0% and 100% (settings at the pyrometer between 0.1 to 1, equivalent to 10 to
100%). Additionally the emissivity is depending on the surface condition of the material, the spectral range of
the pyrometer and the measuring temperature. The emissivity setting of the pyrometer has to be adjusted
accordingly. Typical emissivity values of various common materials for the two spectral ranges of the instru-
ments are listed below. The tolerance of the emissivity values for each material is mainly dependent on the
surface conditions. Rough surfaces have higher emissivities.
In ratio mode (2-color mode) the pyrometer is measuring simultaneously with 2 sensors
in adjacent wavelengths. It calculates the temperature by ratioing the radiation intensities
of the two wavelengths. This ratio technique eliminates a number of factors that degrade
the accuracy of a conventional single color instrument e.g. measurement independent of
emissivity in wide areas, unaffected by dust in the field of view, unaffected by dirty view-
ing windows or lenses, etc. In some cases the emissivities of the two wavelengths can differ so that it is nec-
essary to correct the ratio of the two emissivities (
ε
1 /
ε
2) to get a correct temperature reading. This correc-
tion can be done with the emissivity slope setting K. The K-factors of metals are normally higher than 1. For
a correct measuring result it is recommended to make a comparison test, e.g. with a thermocouple probe.
Then the K-factor has to be corrected until the pyrometer shows the same temperature value.
Emissivity values and emissivity slope values of various common materials are listed below:
Measuring object
Emissivity
ε
(at 0.9 µm)
Emissivity
ε
(at 1.6 µm)
Emissivity slope
K
„Black body furnace“ 1 1 1
Steel heavily scaled 0.93 0.85 to 0.9 1
Steel rolling skin 0.88 0.8 to 0.88 1.00 to 1.01
Settings:
10%
.
.
.
100%
Settings:
0.8
.
.
.
1.2