nss eng college EEE lab results

AIM:
       To control the single phase AC (50V) voltage using a triac.
APPARATUS:
       *Triac
       *Control circuit for triac.
       *230V AC supply.
       *Lamp load.
       *trainer kit.
PRINCIPLE:
        Here the switching device is so operated that load gets connected to AC source for a part of each half cycle of the input voltage.
        For the positive half cycle of the AC voltage triac is triggered at an angle α, and the source get connected to the load. During negative half cycle again the triac is triggered at (α+π).
        By adjusting the triggering angle α,we can adjust the AC voltage magnitude.
PROCEDURE:
        *Connections should made as per the circuit diagram.
        *Switch on the supply.
        *Check whether the lamp load is on.
        *Adjust the triggering circuit potentiometer to control triggering angle to get varying brightness
          Of the lamp.
        *Observe the input voltage, output voltage and output current waveforms in the CRO.
RESULT:
        Single phase AC voltage can be controlled by using a triac and the waveforms are observed.
INTERFERENCE:
        *The AC voltage can be controlled by controlling the triggering angle of triac.
        *The output voltage can be varied from 0 to V (full voltage).
        *The voltage variation is linear.

Fig 1: triggering circuit

Fig2 :triac circuit

output waveform