The Fusible resistor library is one of the component library types within the Component Library included in PI Expert. Fusible resistors are special type of resistors which act as fuses when energy more than a threshold energy passes through them. They are guaranteed not to catch fire when they fuse which is a critical safety requirement. They serve the dual purpose of inrush limiters as well as fuses especially in low power applications. Unlike thermistors their resistance does not dramatically change with temperature. Thus they continuously burn power which limits their use to low power applications.
Only Wire-wound fusible resistors must be used. There is a huge amount of energy dissipated in this component at startup and this can especially cause film type resistors to fail. Wire-wound resistors have parasitic inductance which limits di/dt during startup and prevent failure.
PI Expert does not allow you to modify or delete the default components. You can only view the parameters of a selected component type by clicking the View button. You can add custom components to the Component Library by clicking the Add button in the Component Library dialog where you can input all relevant specifications for a particular component. See the Component Library topic for more information on adding and editing components.
To add a fusible resistor you can specify the following parameters
Type – Use only WIREWOUND resistors for this function.
Resistance – Resistance of fusible resistor
Tolerance – Tolerance of resistor. Usually 5%
Rated Power – Maximum rated power of resistor
Part Number – Manufacturer part number
Manufacturer – Name of manufacturer