A Study of Single-Phase Half-Wave Controlled Rectifier Using R-Load and RL-Load

#LAB 1

STUDY OF SINGLE PHASE HALF WAVE CONTROLLED RECTIFIER USING R - LOAD AND RL - LOAD

OBJECTIVE

To familiarize with the SCR in controlled rectification with resistive (R) and inductive (L) load.

APPRATUS REQUIRED

1. Thyristor Kit

2. Connecting Wires

3. Oscilloscope

4. Multimeter

THEORY

Single-Phase Half-Wave Controlled Rectifier using R - load

The single-phase half-wave controlled rectifier uses a single thyristor with a load and also the output voltage and current waveform as shown in figure 1. In a positive half cycle of source voltage ( = ), thyristor is forward biase

d and when gate current iGis applied to the gate terminal at firing angle α then thyristor strarts to conduct. The output voltage will appear from [illustration not visible in this excerpt] thyristor goes turned OFF. In a negative half cycle,[illustration not visible in this excerpt] thyristor is reverse biased and output voltage is zero during this period. Therefore, by changing the value of firing angle (α) the output voltage can be controlled.

The average output voltage is given by:

illustration not visible in this excerpt

Figure 1 Single Phase half wave controlled rectifier with resistive load

Single-Phase Half-Wave Controlled Rectifier using RL - load

The single-phase half-wave controlled rectifier uses a single thyristor with a RL load and aslo the output voltage and current waveform as shown in figure 2. In a positive half cycle of source voltage ( = ), thyristor is forward biased and when gate current iG is applied to the gate terminal at firing angle α then thyristor starts to conduct. The output voltage will appear from [illustration not visible in this excerpt] thyristor goes turned OFF but current does not decay to zero because of the energy stored in inductor. The negative voltage will appear from [illustration not visible in this excerpt]. The load current decays to zero at [illustration not visible in this excerpt] and value of β depends upon the ratio R/L. During [illustration not visible in this excerpt] to [illustration not visible in this excerpt], the output voltage is zero during this period. The angle β is called extinction angle and [illustration not visible in this excerpt] is called conduction angle.

illustration not visible in this excerpt

Figure 2 Single phase half wave controlled rectifier with resistive-inductive load

OBSERVATION

1. Input Parameter

a. Input voltage ..

b. Frequency ...

c. Cycle time period ...

2. Observation Table

Half wave controlled rectifier with R - load

illustration not visible in this excerpt

Half wave controlled rectifier with RL - load

illustration not visible in this excerpt