J3

Question 1

The basic DC drive system consists of:

Answer 1

A DC motor
a control panel
operator’s control station

Question 2

In a DC drive controller what is a speed reference signal generated for

Answer 2

to start and stop the load smoothly

Question 3

Control cables for DC drives should be

Answer 3

shielded and twisted pair

Question 4

Why should control cables be run in separate conduits from power cables

Answer 4

to protect against electromagnetic interference and mechanical damage

Question 5

What are the two control loops used in a typical adjustable-speed DC drive?

Answer 5

Speed regulator loop and current regulator loop

Question 6

What is the basic difference between a three-phase, full-wave semi-converter and a three-phase, full 6-SCR converter?

Answer 6

regenerative

Question 7

The motor’s compatibility to the power converter can me identified from the motor’s nameplate date under the heading of

Answer 7

power code

Question 8

When a DC motor is used for adjustable-speed list the protection it requires

Answer 8

overcurrent and current limiting protection
overload protection
over voltage protection
field loss protection
over temp
blower for cooling

Question 9

What type of DC motor is normally used for an adjustable-speed application?

Answer 9

compound DC motor with a light series winding

Question 10

What does the marking P1-P2 mean?

Answer 10

Thermal protection contacts

Question 11

Bear in mind the following precautions when working with solid-state starter (AC soft-start)

Answer 11

Heat-sinks may be energized
Do not use a grounded voltmeter for measurements
Do not use a megger for checking semiconductors cct