Hi…as per my knowledge hase angle control varies the effective voltage by connecting the
load to the line only during some fraction of each half cycle,
starting at an adjustable point in each half cycle, and ending at the
next current zero crossing.Burst control varies the effective average voltage (over a longer
time) by connecting the load to an integer number of complete half
cycles in a burst, and then disconnecting the load from the line for
some other integer number of full half cycles. Some systems use
integer full cycles, rather than full half cycles, to prevent any net
DC in the burst waveform. Burst mode has more low frequency ripple
than phase control, but makes less radio frequency and harmonic noise,
because all on switching is done very near the zero voltage points in
the line voltage wave and all switch off points are at zero current
points in the load current wave.
