Question 1

NEMA specifications call for a starter to be derated.

Accepted Answer

NEMA specifications require that motor starters be derated to ensure safe and reliable operation. This means that the starter must be sized larger than the motor it is controlling, to account for any voltage drops, heat dissipation, or other factors that may impact its performance. The amount of derating required will depend on the specific application, but it is generally recommended to follow NEMA guidelines to avoid damage to equipment and ensure optimal performance. NEMA specifications require a starter to be derated by a factor of 115% for continuous-duty applications and 140% for intermittent-duty applications. This is to ensure that the starter can handle a certain amount of overload and is not operating at its maximum capacity.

Question 2

Reversing starters are available in construction.&#10;A)horizontal and vertical&#10;B)parallel and series&#10;C)mechanical&#10;D)power-coil

Accepted Answer

Reversing starters are available in both horizontal and vertical construction. The other options listed are not related to the construction of reversing starters. Reversing starters are commonly available in horizontal and vertical constructions to meet various mounting requirements. The other choices (B, C, and D) are not applicable in this context.

Question 3

The term interlocking is used generally when referring to motor controllers and control stations that are to provide control of production operations.&#10;A)fixated&#10;B)interconnected&#10;C)connected&#10;D)programmed

Accepted Answer

The term interlocking implies that the controllers and control stations are interconnected to provide control of production operations. The other options do not accurately convey this meaning. Interlocking refers to components being connected or interconnected to each other to provide control.

Question 4

If magnetic control devices are to be used, then reversing accomplish the reversal of the motor direction.&#10;A)transformers&#10;B)transducers&#10;C)rotators&#10;D)starters

Accepted Answer

Starters are specifically designed to control the direction of electric motors. Transformers and transducers are not applicable for motor direction control, and rotators are not a specific device for motor control. Starters are devices used to start and control the direction of motor rotation. By reversing the connections in a motor starter, the direction of rotation of the motor can be reversed. Transforming devices like transformers and transducers do not have the ability to control the direction of motor rotation, while rotators are not a type of device used in motor control.

Question 5

A mechanical interlocking device is assembled at the factory the forward and reverse contactors.&#10;A)on top of&#10;B)below&#10;C)between&#10;D)adjacent to

Accepted Answer

A mechanical interlocking device is typically installed between two components to prevent them from operating simultaneously or in the wrong order. Therefore, the correct answer is "between" the forward and reverse contactors. A mechanical interlocking device would need to be assembled between the forward and reverse contactors in order to prevent them from being engaged simultaneously. Placing it on top, below, or adjacent to the contactors would not achieve this purpose.

Question 6

Push-button interlocking is an electrical method of preventing both starter coils from being de-energized simultaneously.

Accepted Answer

Push-button interlocking is a method used in control systems to prevent conflicting operations from occurring simultaneously, such as preventing two incompatible signals from being given at the same time, not specifically related to de-energizing starter coils.

Question 7

Electrical interlocks are usually mounted on the side of a motor starter.

Accepted Answer

Electrical interlocks are usually mounted on the side of a motor starter to prevent unsafe or unintended machine operations. Electrical interlocks are often incorporated into the motor starter design and mounted on the side of the starter to prevent unintended operation or movement of the device.

Question 8

To reverse the direction of rotation of single-phase motors, both the starting and running winding motor leads are interchanged.

Accepted Answer

To reverse the direction of rotation of single-phase motors, only the starting winding leads are interchanged, not the running winding leads.

Question 9

Reversing starters consisting of mechanical and electrical interlocked devices are preferred for .&#10;A)easier maintenance&#10;B)maximum safety&#10;C)easier operation&#10;D)economic reasons

Accepted Answer

Reversing starters with both mechanical and electrical interlocks ensure maximum safety by preventing accidental start-up of the motor in the opposite direction, which can cause damage or injury. While easier maintenance and operation may be benefits of this type of starter, safety is the primary concern. Economic reasons are not a factor in the preference for reversing starters with interlocks. Reversing starters with mechanical and electrical interlocks provide maximum safety, as they ensure that the motor cannot start in the reverse direction without first stopping in the forward direction. This helps prevent accidents and damage to the equipment. While easier maintenance and operation may be benefits of reversing starters, safety should be the primary concern. Economic reasons are not a relevant factor in selecting a reversing starter.

Question 10

The direction of rotation of three-phase motors can be reversed by interchanging any two-motor leads to the line.

Accepted Answer

Swapping any two phases in a three-phase motor will change the direction of rotation. Interchanging any two-motor leads to the line will reverse the direction of rotation in three-phase motors.

Deck 21: Interlocking Methods for Reversing Control