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CAUTION . . . The thermal cutoff may fail to open the electrical circuit under certain conditions.

Distortion of the case, breaking or cracking the seal, exposing the epoxy seal to cleaning solvents,

compression of the leads and current surges that exceed the operating specifications of the thermal

cutoff may cause the thermal cutoff not to open. In addition, pellet shrinkage due to thermal

aging under some circumstances may also result in failure to open. Finally, a very low rate of

temperature rise may produce conditions that may also result in failure to open. Care must be

taken to avoid any mishandling or misapplication of the thermal cutoff.

CAUTION . . . Although TCOs are highly reliable devices, a TCO may fail to open in operation for

one or more of the reasons set forth above. These conditions must be taken into account by the

product design engineer in determining the level of reliability needed for the application. If failure

of the TCO to open could result in personal injury or property damage, the product design engineer

may want to consider using one or more redundant TCOs of different ratings to achieve the

desired level of reliability. A number of consumer product design engineers have incorporated

redundant TCOs of different ratings in their designs for this reason.

Definition of Terms

The maximum temperature at which the thermal cutoff changes its state of conductivity to open

circuit with detection current as the only load. The rated functioning temperature is measured

during a temperature rise of approximately 0.5°C per minute.

The maximum temperature at which, when applying the rated current to the thermal cutoff, the

state of conductivity will not change during a period of one week.

The maximum temperature at which the thermal cutoff, having changed its state of conductivity,

can be maintained for a specified period of time, during which its mechanical and electrical

properties will not be impaired.

Rated Voltage:

The maximum voltage that can be applied to the circuit in which the thermal cutoff is used.

Rated Current:

The maximum current that the thermal cutoff is rated to interrupt at the rated voltage.