Question 1

Time limit acceleration has the disadvantage that the resistors might remain in the circuit and could burn out.

Accepted Answer

False

Question 2

Time limit controllers can drive pumps, fans, and compressors.

Accepted Answer

Time limit controllers are devices that can be used to control the operation of pumps, fans, and compressors by setting a time limit for their operation. This can help to improve energy efficiency and reduce wear and tear on the equipment. Time limit controllers are designed to turn off the attached equipment (such as pumps, fans, and compressors) after a set period of time, making them appropriate for use in situations where the equipment needs to be used for a specific duration.

Question 3

A field failure relay is a single-pole control relay.

Accepted Answer

A field failure relay is a single-pole control relay that is used to protect a motor from damage in the event of a loss of field current.

Question 4

A field accelerating relay is used with starters to control low-cost speed motors.

Accepted Answer

A field accelerating relay is used to reduce the field current during the start-up of a DC motor to increase armature current and torque, not specifically to control low-cost speed motors.

Question 5

A heavy load has more inertia for the motor to overcome; therefore, is required to build up the counter emf.&#10;A)a longer time&#10;B)more voltage&#10;C)a shorter time&#10;D)less voltage

Accepted Answer

A longer time is required to build up the counter electromotive force (emf) when a motor is dealing with a heavy load due to the increased inertia that must be overcome.

Question 6

When a DC motor starts, the generated counter emf across the armature is low.

Accepted Answer

When a DC motor starts, the armature is not moving and therefore there is no relative motion between the conductors and the magnetic field. This means that the generated counter emf across the armature is low, and increases as the motor speeds up. When a DC motor starts, initially the current through the armature is high and the rotation is slow. Hence, at the beginning, the generated counter emf across the armature is low. As the motor gains speed, the counter emf increases and the current decreases.

Question 7

Time limit controllers can be used with series, shunt, or wound DC motors.&#10;A)split&#10;B)advanced&#10;C)permanent&#10;D)compound

Accepted Answer

Time limit controllers are commonly used with compound wound DC motors as they have good starting torque and speed regulation. The time limit controllers are most commonly used with compound wound DC Motors because they have a combination of both series and shunt winding, making them suitable for use with varying load conditions, which is the purpose of the time limit controller.

Question 8

The field accelerating relay the full field during the starting period and limits the armature current during sudden speed changes.&#10;A)displaces&#10;B)restricts&#10;C)provides&#10;D)blocks

Accepted Answer

The field accelerating relay provides the full field during the starting period, which helps in accelerating the motor. It also limits the armature current during sudden speed changes to prevent overloading, overheating, and damage to the motor. Therefore, the best choice is C, i.e., provides. The field accelerating relay provides the full field during the starting period to aid in acceleration and limits the armature current during sudden speed changes to prevent damage to the motor.

Question 9

The running contactor is closed after a definite time interval.&#10;A)completely&#10;B)partially&#10;C)automatically&#10;D)manually

Accepted Answer

The term "automatic" in the question suggests that the running contactor is expected to be closed without the need for manual intervention. Therefore, the best choice is "automatically" (option C). Option A ("completely") is partially correct, but it doesn't quite capture the essence of the question as it doesn't refer to the time interval. Option B ("partially") and D ("manually") can be eliminated as they are unrelated to the context of the question. The question states that the running contactor is closed after a definite time interval, which suggests that it will be closed automatically by some sort of timing mechanism rather than being manually closed by a person. Choice A (completely) and B (partially) do not accurately describe the method of closure, so C (automatically) is the best choice.

Question 10

The definite time limit acceleration provided by the timing relays means that the resistors remain in the line for a fixed time period the motor is connected across the line.&#10;A)after&#10;B)before&#10;C)while&#10;D)if

Accepted Answer

The answer of The definite time limit acceleration provided by...

Deck 46: Compensating and Definite Time Control Starting