The voltage threshold for triggering a Silicon-Controlled Rectifier (SCR) is typically referred to as the "gate trigger voltage" or "gate threshold voltage." This is the minimum voltage that needs to be applied to the gate terminal of the SCR in order to turn it on and allow current to flow between its anode and cathode.
The gate trigger voltage can vary depending on the specific type and model of the SCR, as well as the intended application. Generally, it can range from a few volts to several tens of volts. For many standard SCRs, the gate trigger voltage might be around 0.5 to 2 volts. However, for precise information about the gate trigger voltage of a specific SCR, you would need to consult the datasheet provided by the manufacturer.
It's important to note that triggering an SCR involves more than just applying the gate trigger voltage; the trigger pulse might need to be of a certain duration and current magnitude to ensure reliable and consistent turn-on of the device.