Thanks Michael you inspired me to make it auto 50Hz/60Hz emulator with my new LPC810 demo board with SCT timer.

Since my intention was to emulate 3 phase 50Hz only and project had to finish in one day to make it feasible I did the following:

1. Re-generate PHASE_A in real time from Zero Crossing detector connected to interrupt pin by toggling PHASE_A output pin.

2. On rising edge of PHASE_A output it starts timer0 with fixed on delay mode for 6.67mSec(120 degrees phase shift @ 50Hz) when this timer elapses - interrupt generated, it Sets PHASE_B output hi and reconfigures TMR0 to interrupt after 10mSec and turns PHASE_B low(50 Hz hi output completed).

3. Also on rising edge of PHASE_B output it starts timer1 in fixed on delay mode for 6.67mSec(120 degrees phase shift) when this timer elapses - interrupt generated, it Sets PHASE_C output hi and reconfigures timer1 to interrupt after 10mSec turning off PHASE_B output(50 Hz PHASE_B hi output completed).

4. Programming done in C language and code mainly in interrupt. the main function only contains while loop with rest watchdog timer.
Mahmood