ircon Modline 4, Инструкция по установке и эксплуатации, Страница: 8 / 88

Section 1 – INTRODUCTION
1.2 HOW IT WORKS
The MODLINE 4 works on a simple principle. A heated
object radiates infrared energy, and the intensity of
radiation depends on the temperature of the object. By
measuring the radiation intensity, it is possible to measure
the temperature without contacting the object.
Fig. 1.3 shows a MODLINE 4 series with a digital meter
across a DC power supply. The current in this circuit is
determined by the MODLINE 4.
Infrared radiation enters the lens of the MODLINE 4
and is focused on an infrared detector. The detector
converts infrared energy to an electrical signal that
varies with the intensity of infrared radiation. This
signal is amplified, linearized, and scaled to the desired
temperature range by the MODLINE 4 electronic circuits.
The resulting output current causes the pointer to deflect
on the meter. If the meter scale is matched to the MOD-
LINE 4 range, it’s a simple matter to read temperature
values directly from the scale.
Fig. 1.3 shows how the MODLINE 4 measures a change
in temperature. Assume the MODLINE 4 is scaled for
the 500 to 1500
°
F range. The circuit current is 4 mA
when the MODLINE 4 is viewing a 500
°
F target and
20 mA when viewing a 1500
°
F target. The current
varies linearly between 4 and 20 mA for temperatures
between 500 and 1500
°.
In Fig. 1.3a, the target temperature is 500
°
F. The target
will radiate a certain intensity of infrared energy at
this temperature. When the MODLINE 4 senses this
radiation, it causes 4 mA current in the meter. The
pointer rests at the lowest scale limit (500
°
).
Figures 1.3b and 1.3c shows what happens when
target temperatures increases. The MODLINE 4 detects
more infrared radiation, and the meter current increases
to display higher temperature readings.
Summarizing the action, the MODLINE 4 provides a DC
current proportional to the infrared energy it senses.
This current can be fed through a variety of current-
sensitive devices to indicate temperature or provide a
desired control action.
1-2
FIG. 1. 3 - BASIC OPERATING PRINCIPLE OF
MODLINE 4 INSTRUMENT