Electric motor controls chapter 15

study

Manual

A _____ starter is a contractor with an added overload protective device

Interlock

A mechanical ____ is the arrangement of contacts in such a way that both sets of contacts cannot be closed at the same time

L3

Although any two lines may be interchanged to reverse a 3 phase motor, the industry standard is to interchange L1 and ____

Running

Reversing the rotation of a 1 phase motor is accomplished by interlocking the leads of the starting or ____ windings

Armature

Reversal of a DC compound motor is accomplished by reversing the ____ connections only

Running

____ windings are made of a heavier gauge wire than starting windings, so they have a much lower resistance than starting windings

Parallel interlock

____ lines are used between the manual starters in a wiring diagram to indicate a mechanical interlock

F2

In a DC shunt motor, regardless of wether the forward contacts or reverse are closed, ____ is always positive

Insulated handle

Drum switches are totally enclosed an a ____ provides the means for moving the contacts from point to point

stops

To reverse a running motor using a drum switch, the handle must first be moved to the center position until the motor ____ and then moved to the reverse position

Leads

A drum switch is used only as a means of controlling the direction of a motor by switching the ____ of the motor

Wiring Diagram

Always consult the manufacturer ____ to ensure proper wiring

Fields

The direction of rotation may be reversed in a DC motor by reversing the direction of the current through the armature without changing the direction of the current through the ____

Protective overloads

Drum switches are not motor starters because they do not contain ____

Mechanical

A ____ interlock is normally factory-installed by the manufacturer

Electrical

Although most magnetic reversing starters provide mechanical interlock protection, some circuits are provided with a secondary backup or safety backup system that uses auxiliary contacts to provide ____ interlocking

Control

The ____ circuits includes the required circuit inputs (push buttons, limit switches, etc.), motor starter coils, motor starter auxiliary contacts, overload contacts, timers, and counters

Transformer

Although the power circuit and control circuit operate together to control a motor, they are electrically isolated from each other through a ____

Limit

_____ switches may be used to provide automatic control of reversing circuits

Selector

A ____ switch and a basic start/stop station can be used to reverse a motor

Jogging

A ____ circuit allows the operator to start a motor for short times without memory

Point-to-point

In direct hardwiring, the power circuit and the control circuit are wired ____

Direct hardwired

The disadvantage of a ____ circuit is that circuit troubleshooting and circuit modification are time consuming

Jumpers

If several connections of a given number are required, ____ can be added to the terminal strips to provide multiple connection points to one given terminal number

Point-to-point

_____ wiring is wiring in which each component in a circuit is connected (wired) directly to the next component as specified on the wiring and line diagrams

Power

Troubleshooting reversing ____ circuits normally involves determining the point in the system where power is lost

Line diagram

A ____ is used to illustrate circuit logic

Wiring

A ____ diagram is used to locate the actual test points at which a DMM is connected

Control

A ____ circuit does not operate when the overloads are tripped