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Canadian Advanced Exam Question Bank

effective 4/01/2007

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A-004-02: Filter circuits, bleeder resistor function

A-004-02-01: Filter chokes are rated according to:

inductance and current-handling capacity

reactance at 1000 Hz

power loss

breakdown voltage



A-004-02-02: Which of the following circuits gives the best regulation, under similar load conditions?

A full-wave rectifier with a choke input filter

A half-wave bridge rectifier with a capacitor input filter

A half-wave rectifier with a choke input filter

A full-wave rectifier with a capacitor input filter



A-004-02-03: The advantage of the capacitor input filter over the choke input filter is:

a higher terminal voltage output

better filtering action or smaller ripple voltage

improved voltage regulation

lower peak rectifier currents



A-004-02-04: With a normal load, the choke input filter will give the:

best regulated output

greatest percentage of ripple

greatest ripple frequency

highest output voltage



A-004-02-05: There are two types of filters in general use in a power supply. They are called:

choke input and capacitor input

choke output and capacitor output

choke input and capacitor output

choke output and capacitor input



A-004-02-06: The main function of the bleeder resistor in a power supply is to provide a discharge path for the capacitor in the power supply. But it may also be used for a secondary function, which is to:

improve voltage regulation

provide a ground return for the transformer

inhibit the flow of current through the supply

act as a secondary smoothing device in conjunction with the filter



A-004-02-07: In a power supply, series chokes will:

readily pass the DC but will impede the flow of the AC component

readily pass the DC and the AC component

impede the passage of DC but will pass the AC component

impede both DC and AC



A-004-02-08: When using a choke input filter, a minimum current should be drawn all the time when the device is switched on. This can be accomplished by:

adjusting the bleeder resistance

utilizing a full-wave bridge rectifier circuit

placing an ammeter in the output circuit

increasing the value of the output capacitor



A-004-02-09: In the design of a power supply, the designer must be careful of resonance effects because the ripple voltage could build up to a high value. The components that must be carefully selected are:

first choke and first capacitor

the bleeder resistor and the first choke

first capacitor and second capacitor

first choke and second capacitor



A-004-02-10: Excessive rectifier peak current and abnormally high peak inverse voltages can be caused in a power supply by the filter forming a:

series resonant circuit with the first choke and first capacitor

short circuit across the bleeder

parallel resonant circuit with the first choke and second capacitor

tuned inductance in the filter choke



A-004-02-11: In a properly designed choke input filter power supply, the voltage across the filter capacitor will be about nine-tenths of the AC RMS no-load voltage; yet it is advisable to use capacitors rated at the peak transformer voltage. Why is this large safety margin suggested?

Under no-load conditions and a burned-out bleeder, voltages could reach the peak transformer voltage

Resonance can be set up in the filter producing high voltages

Under heavy load, high currents and voltages are produced

Under no-load conditions, the current could reach a high level





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A-004-01: Transformer and rectifier circuits, voltage doubler circuit, PIP
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A-004-03: Linear and switching voltage regulator circuits
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