POWER ELECTRONICS-Q1 (January 2019)

Material that electricity can easily flow through

• Insulators
• Rubber
• Conductor
• Wood

Identify the Converter type?

• 1Φ Dual Converter
• 3Φ Single Converter
• 3Φ Dual Converter
• 1Φ Single Converter

A fully controlled converter uses

•  diodes only
•  thyristors only
•  both diodes and thyristors
• Noe of them

In the single-pulse width modulation method, the output voltage waveform is symmetrical about __________ ?

• π
• 2π
•  π/2
• π/4

For an SCR in the forward blocking mode (practically)

• leakage current does not flow
• leakage current flows from anode to cathode
• leakage current flows from cathode to anode
• leakage current flows from gate to anode

 A dual converters has

•  two full converters in series
•  two half converters in series
• two full converters in anti-parallel
• two half converters in anti-parallel

The four quadrant operation of dual converters can be obtained by

• changing the firing angle value
• moving the mechanical lever
• adding inductance to the circuit
• none of the mentioned

 The shape of the output voltage waveform in a single PWM is

•  square wave
• triangular wave
• quasi-square wave
• sine wave

dv/dt protection is provided to the SCR by

• connecting a capacitor in parallel with the load
• connecting an inductor in series with the load
• connecting a capacitor & resister in parallel with the device
• connecting an inductor & resister in parallel with the device

The time constant of a series RC circuit (τ) is given by

• R/C
• C/R
• RC
• 1/RC