The Silicon Controlled Rectifiers (SCR) library is one of the component library types within the Component Library included in PI Expert.. Once a silicon controlled rectifier is added to the library and included in a Component Set, you can manually choose your custom SCR to be used where applicable. SCRs are currently used in the damper circuit for LED applications that need to be compatible with TRIAC dimmers.
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.
You can specify the following silicon controlled rectifiers parameters:
Type - Silicon controlled rectifier type
On-State IRMS, A - Maximum RMS on-state current (assuming 180° conduction angle)
Surge Current - Non repetitive peak on-state current in Amps (A)
V Off-State - Maximum Cathode to Anode voltage value in "off-state" in Volts (V)
Sensitivity - Maximum gate current that will guarantee that SCR will turn on in micro Amps (µA)
The following settings are common to all component type parameter dialogs:
Manufacturer - The name of the company that manufactures the component.
Part Number- The part number that uniquely identifies the component.
Click OK to add the silicon controlled rectifiers to the library. The 
User mark will indicate the custom silicon controlled rectifier in the list.