Why always diode are connected parallel to scr?

A diode is connected in parallel with a Silicon Controlled Rectifier (SCR) to provide a path for reverse current during the turn-off process. When the SCR is turned off, it may experience a reverse voltage, and the diode allows this reverse current to bypass the SCR, preventing damage from high voltage spikes. This configuration helps protect the SCR from voltage transients and ensures proper operation in circuits where inductive loads are present.