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MICROTEMP®
thermal cutoffs are available in a wide range of opening temperatures
providing designers with a high degree of design flexibility (See
figure 4). Determining the correct TCO temperature calibration requires
significant application testing.
The proper TCO
calibration will be affected by application variables such as I2R
self heating of the TCO, heat transfer through insulation and heat
dissipation due to heat sinking and air flow.
Thermocoupled
"dummy" TCOs which match the physical and electrical characteristics
of a functional TCO are available to help evaluate application specific
variables.
For more information
on testing and installing MICROTEMP TCOs, please review Therm-O-Disc’s
MICROTEMP® Thermal Cutoff Technical Bulletin, "Application
and Installation of MICROTEMP® Thermal Cutoffs.".”
Temperature Limits of the MICROTEMP®TCO
The temperatures
experienced during normal operation, including expected temperature
overshoots, will determine the life expectancy of the TCO. Nuisance
trips can result if the thermal cutoff rating is too close to the
temperatures experienced during normal operation. Continuous temperatures
above 200°C will cause the sealing compound to weaken and ultimately
fail. In addition, as shown in figure 4, each thermal cutoff calibration
has a maximum temperature overshoot rating (TM). Overshoot temperatures
above this rating may cause dielectric breakdown of the thermal
cutoff and allow reconduction to occur. See Therm-O-Disc’s MICROTEMP®
Thermal Cutoff Technical Bulletin for more information.
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