2. M
U
E
T
JAMSHORO
Department
of
Electrical
Engineering
If a semiconductor switch is connected
between ac supply and load, the power flow
can be controlled by varying the rms value of
ac voltage applied to the load; and this type of
power circuit is known as ac voltage controller.
AC Voltage Controllers
7. M
U
E
T
JAMSHORO
Department
of
Electrical
Engineering
The basic principle of on-off control technique is explained
with reference to a single phase full wave ac voltage
controller circuit shown below. The thyristor switches T1and
T2 are turned on by applying appropriate gate trigger pulses
to connect the input ac supply to the load for ‘n’ number of
input cycles during the time interval Ton. The thyristor
switches T1 and T2 are turned off by blocking the gate
trigger pulses for ‘m’ number of input cycles during the time
interval Toff. The ac controller ON time Ton usually consists
of an integral number of input cycles.
14. M
U
E
T
JAMSHORO
Department
of
Electrical
Engineering
APPLICATIONS OF AC-AC CONVERTERS
The most common applications of AC-AC converters are:
Industrial heating and domestic heating
On-load transformer connection changing
Light controls
Speed control of poly phase Induction Motors
AC magnet controls
Air-craft
Household appliances
Electronic ballasts.
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