Temperature Feedback Using An Ir Device; Positioning Of Ir Sensor When Using Two Rolling Inductors - Miller 301182 Owner's Manual

6-2. Temperature Feedback Using An IR Device

Definitions:
Infrared Radiation (IR) - Radiation that has a wavelength between the red end of the visible light spectrum and microwaves (approx. 800nm to 1mm). It
is emitted in particular by heated objects and can be used to determine temperature.
Emissivity - A dimensionless quantity describing the efficiency with which a material radiates infrared energy. For metals, it varies greatly depending on
the type of metal and its surface condition. Emissivity has a range from 0 to 1.
Reflectivity - The ability of an object to reflect energy emitted by other objects.
True Temperature - The actual temperature of an object.
Apparent Temperature - The temperature read by a sensor. It is a function of the true temperature, emissivity, and reflectivity.
Accuracy Range - The range of temperature in which the device is accurate.
Accuracy and Emissivity:
The accuracy of the IR will be highly dependent on the surface conditions of the workpiece and the type of sensor purchased.
Typical low end sensors are accurate in a small range of temperatures at a given emissivity. This requires the work piece to have a consistent surface
finish. A flat black finish will have an emissivity approaching 1 while a shiny surface will have an emissivity approaching 0. Since typical devices are set
to higher emissivity values (0.8 to 1.00), a workpiece with mill-scale/rust will typically provide more accurate feedback than a shiny, prepped joint.
Some higher end devices can accommodate emissivity changes. This is done through filtering the IR signal from the part in different spectrum ranges
and results in better accuracy over the low end devices.
The IR device you choose will depend on the material, surface preparation and the accuracy that you require when monitoring the workpiece tempera-
ture.
Output Type
Single Rolling Inductor
Dual Rolling Inductor

6-3. Positioning Of IR Sensor When Using Two Rolling Inductors

Table 6-1. Rolling Inductor Output Characteristics
*The system maximum power is 35 kW, so each output will have approximately 17.5 kW, which uses
Maximum Amperage
300 A
300 A Per Output*
less than 300 A
.
When centering the rolling in-
ductor on a joint, the IR should
be centered 1 in. From either
edge of the joint.
A
A
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