What effect does increasing the firing angle delay have on output power?

Increasing the firing angle delay in a controlled rectifier circuit, such as a silicon-controlled rectifier (SCR), leads to a reduction in output power. This occurs because the firing angle determines when the SCR is turned on within each cycle of the input AC waveform.

When the firing angle is increased, the conduction period of the SCR is delayed, meaning it turns on later in the AC cycle. This results in less area under the voltage-current characteristic curve during each cycle, ultimately reducing the average output voltage and consequently the output power delivered to the load.

For example, if the firing angle is set closer to 0 degrees, the SCR conducts for a longer duration during each half-cycle, allowing more power to flow. However, as the firing angle approaches 90 degrees, the conduction time decreases, significantly lowering the output power.

The other options do not align with the principles of phase control in SCR circuits, as increased firing angles do not increase power, have no effect, or reverse power output. This understanding is critical for applications that rely on phase control for managing power delivery.