Exposure Time (T90); Clear Time Of The Maximum Value Storage (Tclear) - LumaSense Technologies IMPAC IP 140-LO Betriebsanleitung

IMPAC pyrometer IP 140-LO
9.3

Exposure time (t90)

The exposure time is the time interval when the measured temperature has to be pre-
sent after an abrupt change so that the output value of the pyrometer reaches a given
measurement value. The time taken is to reach 90 % of the recorded temperature dif-
ference. In the "min" position, the device operates using its time constant.
The dynamic exposure time adjustment prolongs the exposure time at the lower range
limit, also it t is set to a lower value.
90
The following table shows the dependence of the exposure time from the measured temperature.
Switch points on increasing temperatures:
Temperature range
100 ... 650°C (MB 6.5)
110 ... 670°C (MB 6.7)
130 ... 750°C (MB 7.5)
If the maximum value storage is selected and the measuring object has a low emissivity and the measuring
temperature is at the beginning of the range, a higher exposure time must be chosen to prevent measure-
ment errors. Longer exposure times can be used for the measurement of objects which have rapidly fluctuat-
ing temperatures to achieve constant temperature reading.
9.4

Clear time of the maximum value storage (tClear)

If the maximum value storage is switched on always the highest last temperature value
will be displayed and stored. The storage has to be cleared at regular intervals for
exchanging by a new and actual value.
This feature is particularly useful when fluctuating object temperatures cause the dis-
play or the analog outputs to change too rapidly, or the pyrometer is not constantly
viewing an object to be measured. In addition, it may also be beneficial to periodically
delete and reset the stored maximum values.
The following settings are possible:
off: At clear time "off" the max. value storage is switched off and only momentary values are meas-
ured.
0.01...25 s: If any clear time between 0.01 s and 25 s is set, the maximum value is estimated and held in
double storage mode. After the entered time the storage will be deleted.
extern: The external clearing can be activated and used within an own software (see section 14, Data
format UPP
socket on the back of the pyrometer). In this case, the storage operates only in single stor-
age, because only a single deletion mechanism is used.
auto: The "auto" mode is used for discontinuous measuring tasks. For example objects are trans-
ported on a conveyer belt and pass the measuring beam of the pyrometer only for a few sec-
onds. Here the maximum value for each object has to be indicated. In the "auto" mode the
maximum value is stored until a new hot object appears in the measuring beam. The tempera-
ture which has to be recognized as "hot" is defined by the low limit of the temperature range.
The stored maximum value will be deleted when the temperature of the new hot object exceeds
the low limit of the temperature range or adjusted temperature sub range by 1% or at least 2°C.
Hold: The function "hold" enables to freeze the current temperature reading at any moment. For this
an external push button or switch has to be connected (see 4.1.1 Connector pin J) which holds
the temperature reading as long as the contacts are closed.
Operation note: dependent on the settings the maximum value storage either works in single storage mode
or in double storage mode:
Single storage: the single storage is used when you want to reset the stored value using an external im-
pulse via one contact closure from an external relay (i.e. between two measured objects). The relay contact
is connected directly to the pyrometer between pins J and K. This mode allows a new value to be estab-
lished, after each impulse from the reset signal.
16
switch points for ε = 1
35 ms → 5 ms
165°C
170°C
188°C
®
) or via an external contact (for connection see 4.1 Pin assignment of the male
5 ms → 1,5 ms 35 ms → 5 ms
215°C
220°C
242°C
Settings:
min
0.01 s
0.05 s
. .
.
10.00 s
switch points for ε = 0,5
5 ms → 1,5 ms
189°C 243°C
194°C 250°C
214°C 274°C
Settings:
off
0.01 s
. .
.
25 s
extern
auto
Hold