Question 1

According to Fleming's left&#173;hand rule, motor action will tend to force the conductor in a downward direction.

Accepted Answer

False

Question 2

Most operating coils are by contacts to prevent an accidental coil burnout.&#10;A)disconnected automatically&#10;B)monitored regularly&#10;C)connected intermittently&#10;D)normally disconnected

Accepted Answer

Operating coils are disconnected automatically by contacts to prevent accidental coil burnout, ensuring they are not energized for too long.

Question 3

The larger contactor sizes are used to provide remote control of relatively high-current circuits where it is too expensive to run the power leads to the remote controlling location.

Accepted Answer

Larger contactor sizes are indeed used to provide remote control of circuits that carry high currents, especially when it is not feasible to run power leads to the remote controlling location. This statement is true. Larger contactor sizes are often used to provide remote control of high-current circuits, particularly in situations where it would be prohibitively expensive to run power leads to the remote controlling location. Contactors provide an efficient and cost-effective way to control the flow of current in electrical circuits, and larger sizes can handle higher currents and offer greater control over more complex electrical systems.

Question 4

A mechanically held or latching relay is operated by electromagnets.

Accepted Answer

A mechanically held or latching relay is operated by electromagnets. A mechanically held or latching relay uses electromagnets to hold the contacts in either an open or closed position until the opposite polarity current is applied to release them.

Question 5

With , the blowout coil magnetic field and the conductor (arc) magnetic field will reverse simultaneously.&#10;A)AC polarity&#10;B)AC current&#10;C)DC polarity&#10;D)DC current

Accepted Answer

The reversal of the magnetic field in both the blowout coil and the conductor (arc) occur simultaneously with changes in AC current direction, not with changes in DC polarity or current. The reversal of magnetic fields in both the blowout coil and arc conductor occur when the current changes direction, which is a characteristic of AC current. In DC current, the magnetic fields do not reverse because the current flows in only one direction. Therefore, the correct choice is B) AC current.

Question 6

An arc-quenching device is used to ensure .&#10;A)better extinguishing action&#10;B)better contact&#10;C)longer contact life&#10;D)more power

Accepted Answer

The answer of An arc-quenching device is used to ensure...

Question 7

Mechanically held relays are often used in machine tool control circuits.

Accepted Answer

Mechanically held relays are commonly used in machine tool control circuits as they are reliable and ensure that the circuit remains closed even in the event of power loss. Mechanically held relays are commonly used in machine tool control circuits for their ability to maintain their state even after the control signal is removed. This allows for more efficient operation of the machine tool.

Question 8

Generally, mechanically held relays are available in 10- and -ampere sizes.&#10;A)12&#10;B)15&#10;C)20&#10;D)24

Accepted Answer

Mechanically held relays are commonly available in 10- and 15-ampere sizes, catering to various electrical load requirements.

Question 9

The function of the blowout magnet is to move the arc downward at the same time that the contacts are opening.

Accepted Answer

The function of a blowout magnet is to deflect or extinguish the arc by using a magnetic field, not specifically to move it downward.

Question 10

Time clocks and photo cells are generally .&#10;A)used to control AC motors&#10;B)provided to monitor the contactors&#10;C)provided for overload protection&#10;D)used for lighting loads

Accepted Answer

Time clocks and photo cells are typically used for controlling lighting loads, such as turning them on and off at specific times or in response to changes in daylight. They are not commonly used for AC motor control, monitoring contactors, or overload protection. Time clocks and photo cells are commonly used for controlling lighting loads, such as turning lights on and off based on specific times or the amount of daylight.

Deck 8: Contactors