Precautions For The Use Of Thermal Cutoff Fuse
Today, we will introduce the precautions for the use of thermal fuse.
● When installing and designing, pay attention to the long-term continuous working environment temperature of thermal fuse not to exceed their holding temperature.
● The thermal fuse is a non-resettable device. For safety reasons, when replacing the thermal fuse, please select the thermal fuse of the same model and install it in the same location.
● When designing and applying products, make sure that the thermal fuse only feels the required heat source. For example: when used in a heater, the thermal fuse cannot be directly connected to the heating wire, and must be isolated from the heating wire by a non-heating wire, so that the heat of the heating wire will not pass through the pin into the thermal fuse and accelerate it For example, when applied to a transformer or a motor, the temperature should be controlled inside the coil, so the thermal fuse must have good heat conduction with the coil.
● Application products must be tested to ensure that when any abnormal conditions occur, the temperature around the thermal fuse will not exceed its limit temperature (TM). This condition may occur under a condition called "residual heat overshoot". For example: A hot air blower causes the temperature to rise to TF when the air inlet or outlet is blocked. At this time, the thermal fuse breaks the circuit. However, an incorrect design may cause the device to open in advance and excessive residual heat overshoot may damage it. Fuse, the application product must be tested to determine that under normal temperature fluctuations (such as the temperature fluctuation of the heater caused by the action and reset of the thermostat), the temperature around the thermofuse will not reach TM during the on-off cycle of the thermostat
● It is recommended to use a model with a built-in thermocouple temperature fuse to select and determine the appropriate rated temperature specification and installation location during design.
● Do not install the thermal fuse in places subject to severe vibration.
● The thermal fuse can be connected by soldering, spot welding, or twisting.
● When bending the pins, you must use tools to ensure that the bending of the pins has sufficient curvature. The pins should not be bent within 3mm from the root. The tool should not clamp the shell and sealing resin during bending.
● The sealing resin and the shell must not be damaged, burnt or overheated.
● Non-twistable thermal fuse (for example: the pin rotates relative to the housing).
● Avoid applying an angled force on the pins (such as pushing or pulling the pins at an angle relative to the outer shell), which will damage the sealing resin.
● When fixing the thermal fuse, do not apply excessive pressure on the shell, sealing resin or pins (such as pulling the fuse, over-clamping, or over-tightening). This will damage the fuse or cause stress to concentrate on the pins.
● The connecting lead should have enough remaining length and be soft enough, and the thermal fuse and the twisted joint should be fixed to avoid the loosening of the twisted joint caused by vibration under normal use conditions.
● The axial force (pull or thrust) exerted on the pin must not exceed the specified test "pull" or "push". For block type fuses, the maximum test pull is 1 pound and the maximum test thrust is 0.4 pound (at room temperature). Bottom), a sample test must be done first to ensure that the maximum test "pull force" and "push force" will not be generated on the pins during the production process.
● When designing and applying products, it is necessary to consider the stress caused by the shrinkage, expansion and other movement of the component materials that are in contact with the pins and shells. Soft, bendable or cold, low-resistance leads should be used to connect to the thermal fuse .
● The contact resistance must be controlled to ensure the lowest resistance. Improper connection will cause the fuse to act prematurely. The contact must be sampled to ensure that the connection has a suitable mechanical connection strength. An improper connection point will cause the contact resistance to increase and then the contact Generate high temperature, causing damage to the sealing resin and other parts, which may cause short circuits or other failures in the device.
