TECHNOLOGY BASICS.................................................................

Polymeric PTC material and device technology synergistically integrate the advance polymer material technologies, conductive material science, novel processing engineering, and fundamental electronic and electrical theory. Electrical resistance of such material and devices increases with temperature increases and vice versa. When experiencing "overcurrent and/or over voltage", the device generates thermal energy (Energy = I*V) and heats up itself. This makes polymer matrix's morphology change from crystalline to amorphous phase, and results in a resistance increase of thousand orders of magnitude such that "trip" the electricity. The device will remain hot and stay "tripped" until the fault is cleared and power removed.

HOW DOES THE RESETTABLE FUSE WORK ....................................

FUSETRONIC resettable fuses are designed and made of patented novel polymeric PTC material in thin chip form, developed solely by FUSETRONIC. With electrodes and leads attached on both sides, it is placed in a series to protect a circuit. At "normal operating condition", the device remains at anxtremely low resistance (mini-ohms) and allows thelectrical current to flow through it without any restriction. When overcurrent condition occur, the Polymeric PTC material heats up, and its resistance increases sharply. Such a sharp resistance increase (to an insulated status) cuts off the current in the circuit, and consequently protects thelement and device in the circuit. Upon faulty current being removed, the resettable fuse cools and its resistance drops to the originalxtremely low value. The resettable fuse is "resetted"; and allows the current through the circuit again.

TRIP CURRENT, HOLD CURRENT AND THERMAL DERATING .............

Trip Current (IT) and Hold Current (IH) of resettable fuse are rated at 23C. Typically its Trip Current is twice as much as its Hold Current. FUSETRONIC device will not trip at its Hold Current or blow and will trip at or above its Trip Current. However, due to the PTC effect both IT and IH reduces with ambient temperature increase and vice versa. As shown on Figure 3, the currents are reduced nearly 50% at 85C and increased to 150% at -40C.