AUPO

AUPO ALLOY TYPE THERMAL CUTOFF APPLICATION INSTRUCTION

Please study these instructions before designing or installing AUPO Thermal Cutoffs (thermal-links). These instructions are provided to reduce the risk of malfunction of thermal cutoffs which may result from improper design, installation methods and harmful operating conditions which may occur during use in the end-product.
●Each thermal cutoff has specific Electrical and Temperature Rating and must be used within the prescribed ratings. These ratings include TF (Rated Functioning Temperature), TH or Tc (Holding Temperature), TM (Maximum Temperature Limit), and the electrical ratings. Please refer to the AUPO THERMAL CUTOFFS Catalogue for specific ratings and further explanation of these terms.

●Install thermal cutoffs so that their temperature do not continuously exceed the Holding Temperature specified in the individual specification.
●For reason of safety that a thermal cutoff is a non-repairable item and that, in case of replacement, an equivalent thermal cutoff with the same catalogue number shall be used, mounted in exactly the same way.

●The end product should be designed so that the thermal cutoff detects only the intended heat source (radiant, convection, and/or conductance). For example, in a heater application, the thermal cutoff should never be directly connected to the heater wire and should be isolate to the heater wire by a "cold" pin so that conductance through the lead wire dose not accelerate the fusing off of the thermal cutoff. In case of a transformer or motor application, where the temperature should be controlled in a transformer or motor coil, the thermal cutoff should have good heat conductive contact with the transformer or motor coil.

●It is recommended that using the dummy thermal cutoff having an internal thermocouple to select the proper temperature rating and location of the thermal cutoff.
●Do not locate the thermal cutoff on an assembly subjected to severe continuous vibration.
●The thermal cutoff can be connected by soldering, welding or splicing.
●The end product should be tested to ensure that potentially abnormal conditions do not exposed the thermal cutoff to the temperature exceeding its TM. This condition may occur in an "overshoot" situation. For example, an air heater may be subjected to a blocked inlet or outlet condition on attaining its TF, the thermal cutoff will open. However, an incorrect design may cause the premature opening of the device and excess overshoot may cause shooting or damage to the thermal cutoff. The end product should be tested to ensure that under normal cycling condition (such as heater cycling of a thermostat), the thermal cutoff never reaches its TF during the "on" or "off" cycle(see Fig. 1)
.

                             (Fig. 1)
●When forming leads, a tool should be used to ensure that the leads are formed with sufficient curve. Leads should not be bent closer then 3mm to the thermal cutoff body. Holders or tools used during lead forming must be kept away from seal or body. (see Fig. 2)

             X: Incorrect                 O: Correct
                              ( Fig. 2 )
●Leads should not be cut, nicked, folded sharply, fractured or burned during forming or installation.
● he seal or body must not be damaged, burned or over heated.
●Do not twist the thermal cutoff, (i.e. rotation of lead with respect to the body).
●Tangential forces on the leads must be avoided (i.e. pushing or pulling on the leads at an angle to the thermal cutoff body) as such forces may damage the thermal cutoff's seal.
●Securement of the thermal cutoff after making connections should not put excessive pressure on the thermal cutoff body, seal or leads ( i.e. pushing the thermal cutoff, excessive clamping or two tight of a wrap) which could result in denting of the thermal cutoff or place pushing or pulling stress on the leads.
●Appropriate free lengths of wire and sufficiently flexible wire connections should be used. The thermal cutoff and splices should be secured to prevent vibration or flexing of the thermal cutoff and splices during normal operation.
●Axial stress (pull or push) on the leads must never exceed the maximum tested "pull" or "push" force. For A series "AUPO" thermal cutoffs, maximum tested "pull" force is 1 pound, and maximum tested "push" force is 0.4 pound, at room temperature. Experimental assembly trials should be made to verify that manufacture procedures will not exceed the maximum tested "pull" and "push" force on the leads.
●Stress due to expansion and contraction of parts attached to the leads or body, vibration or other movements of parts should be considered when designing the end product. A flexible or bent heater lead or a cold, low resistance heater lead should be used to connect to the thermal cutoff.
●Resistance of connections should be monitored to ensure minimal resistance. Improper connections or secure may result in premature failure of the thermal cutoff. Samples of joints should be inspected to ensure adequate mechanical bonding of lead to connection wires. Improper connections can cause damage to the seal or other parts which may result in shorting or nuisance tripping of the devices due to the generation of excessive heat at a faulty high resistance junction.
●When soldering or welding, used thermal cutoff leads as long as possible. Long leads permit a longer soldering time and reduce the possibility of overheat. Table 1 is provided as a guide to maximum soldering time with a lead length of 10mm (one end only) at 300 degree C.

Table 1

Rated Functioning Temperature ( TF )	Soldering Time ( second )
102 - 115℃	1
125 - 139℃	2
150℃	3

●Because the thermal element of thermal cutoff is a fusible alloy which connected with lead wires, improper soldering operation (too high the soldering temperature, too long the soldering time, too short the lead wire used etc) will cause thermal element injured by the excessive heat transmit from the lead wire which may result in premature opening of the themal cutoff.The following are some methods to prevent the thermal cutoff from damaged by overheat during soldering operation:
Using the lead wires as long as possible when soldering, longer leads permit a longer soldering time and reduce the possibility of overheating. Fig 3 is an example of how to keep a longer lead wires when a thermal cutoff is installed in an example of how to keep a longer lead wires when a thermal cutoff is installed in a small space. It is recommended that using a heat sink between the soldering point and sealant to minimize the heat transmission to thermal cutoff. Avoid the soldering temperature is too high and keep the soldering time as short as possible.

(Fig. 3)
●During the soldering or welding, leads should be supported properly, otherwise, the leads or seal may be damaged. Pulling or twisting of the lead wires while sealant is hot may cause it to separate from the body and/or leads which can cause mechanical failure. Therefore, do not twist the thermal cutoff after soldering or welding until the sealant has cooled. Wait at least thirty seconds before re-soldering, taping, securing or reposition the thermal cutoff. Cooling time depends on soldering temperature, soldering (or welding) time, lead length etc. It is recommended that you run test to determine the best soldering (or welding) time, temperature and heat sinking on the product.

●Electrical current must not pass through element when welding.

●Mechanical security must not depend on solder along.

●ncoming shipments should be examined for evidence of damage during transportation. It is recommended that further examination be made after installation in the end product. Conductance measurements or X-raying before and after installation are recommended.
●Prototype or early production samples and also experimental assembly trials should be operated under normal and abnormal condition with temperature measured on the thermal cutoff and on critical parts of the appliance or other end product. After the test the thermal cutoff and appliance should be examined.