Question 1

What does inhibit and enable contacts mean?

Accepted Answer

More often than not, when normally closed control contacts under the operation of a coil are used in the ladder rung logic, their purpose is to prevent two operations from happening at the same time.Because of this, normally closed contact devices on ladder rungs are sometimes called inhibit contacts or devices, because the action of one operation inhibits some other operation from acting simultaneously.Likewise, more often than not, when normally open control contacts under the operation of a coil are used in the ladder rung logic, their purpose is to enable some other operation to happen at the same time.Because of this, normally open contact devices on ladder rungs and are sometimes called enable contacts, because the action of one operation enables some other operation to act simultaneously.

Question 2

When control circuit power is first applied to the three-wire motor control circuit, the rails become ____.

Accepted Answer

When control circuit power is first applied to the three-wire motor control circuit, the rails become energized. This allows for the control circuit to operate and activate the motor.

Question 3

The normally closed Stop pushbutton is wired as the third control component in the ladder rung, so that it has master control over the entire rung.

Accepted Answer

The normally closed Stop pushbutton, when wired in a ladder rung, does not have "master control" over the entire rung; it simply stops the circuit when pressed, regardless of its position in the sequence of control components.

Question 4

Normally closed contact devices on ladder rungs are sometimes called "exhibit" contacts or devices.

Accepted Answer

Normally closed contact devices on ladder rungs are known as "interlock" contacts or devices, not "exhibit" contacts or devices.

Question 5

Stop pushbuttons are normally closed contact configurations.Why?

Accepted Answer

The answer of Stop pushbuttons are normally closed contact configurations.Why?...

Question 6

Once the motor starter contactor control coil is energized, and being held energized by the holding contacts, pressing the normally closed Stop pushbutton will de-energize the control coil; causing the contactor holding contacts to open.

Accepted Answer

When the Stop pushbutton is pressed, it interrupts the power supply to the control coil, which causes it to de-energize and opens the holding contacts of the contactor. This breaks the circuit and stops the motor from running.

Question 7

Once the motor starter contactor is energized and closes the holding contacts, the holding contacts provide a redundant electrical path around the normally open Start pushbutton contacts, to keep the contactor control coil energized.

Accepted Answer

This is correct, the holding contacts provide an alternative path for current to flow, bypassing the Start pushbutton contacts and keeping the contactor coil energized.

Question 8

Normally open contact devices on ladder rungs and are sometimes called ____ contacts.

Accepted Answer

Normally open contact devices in ladder logic diagrams are referred to as "enable" contacts because they allow current to flow when activated.

Question 9

Permanent contact control devices are called-out as either normally open or normally closed.

Accepted Answer

The answer of Permanent contact control devices are called-out as...

Question 10

Normally closed contact devices on ladder rungs are sometimes called ____ contacts or devices.

Accepted Answer

Normally closed contact devices on ladder rungs are designed to inhibit or stop the flow of electricity when the device is activated. This is in contrast to normally open contact devices, which allow the flow of electricity when activated. Therefore, the best choice is C) inhibit.

Question 11

When control devices are connected in parallel, they form the Boolean "_______________" function.

Accepted Answer

The answer of When control devices are connected in parallel,...

Question 12

The second device in the motor control ladder diagram run is the ____ pushbutton.

Accepted Answer

In a typical motor control ladder diagram, the start pushbutton is usually the second device after the stop pushbutton.

Question 13

Three-wire motor control circuits are called three-wire, because there are three _______________ circuit wires between the motor starter and the control device(s).

Accepted Answer

The answer of Three-wire motor control circuits are called three-wire,...

Question 14

Three-wire control circuit components may be either maintained contact or momentary contact, but the _______________ contact function is specific to three-wire control.

Accepted Answer

The answer of Three-wire control circuit components may be either...

Question 15

_______________ contacts are a normally-open set of contacts mounted on the contactor portion of the motor starter, and are actuated by the armature of the contactor unit.

Accepted Answer

The answer of _______________ contacts are a normally-open set of...

Question 16

When the ____ pushbutton is pressed, the control circuit power will pass through to the motor starter contactor control coil S1.

Accepted Answer

When the "start" pushbutton is pressed, it completes the circuit allowing power to flow through to the motor starter contactor control coil S1, initiating the motor operation.

Question 17

____ contact control devices change states when acted upon, but then return to their original state when released.

Accepted Answer

Momentary contact control devices only change states when acted upon, but then return to their original state when released. Standard and pushbutton control devices can remain in their changed state until acted upon again, and magnetic control devices use magnetic fields to trigger a change in state.

Question 18

One of the other names of holding contacts is ____ contacts.

Accepted Answer

Memory contacts are also known as holding contacts because they "remember" or maintain the state of a control circuit (e.g., keeping a relay energized) even after the initiating signal is removed.

Question 19

The ____ pushbutton will always be the first device off of L1, so that it has "master control" of the rung.

Accepted Answer

The stop pushbutton is placed first off of L1 in a control circuit to ensure it has "master control" over the rung, allowing for immediate stopping of the circuit for safety and control reasons.

Question 20

Three-wire motor control circuits have three control circuit wires between the motor starter and the control device(s).

Accepted Answer

Three-wire motor control circuits have three control circuit wires between the motor starter and the control device(s).

Quiz 13: Three-Wire Motor Control

What does inhibit and enable contacts mean?

When control circuit power is first applied to the three-wire motor control circuit, the rails become ____.

The normally closed Stop pushbutton is wired as the third control component in the ladder rung, so that it has master control over the entire rung.

Normally closed contact devices on ladder rungs are sometimes called "exhibit" contacts or devices.

Stop pushbuttons are normally closed contact configurations.Why?

Once the motor starter contactor control coil is energized, and being held energized by the holding contacts, pressing the normally closed Stop pushbutton will de-energize the control coil; causing the contactor holding contacts to open.

Once the motor starter contactor is energized and closes the holding contacts, the holding contacts provide a redundant electrical path around the normally open Start pushbutton contacts, to keep the contactor control coil energized.

Normally open contact devices on ladder rungs and are sometimes called ____ contacts.

Permanent contact control devices are called-out as either normally open or normally closed.

Normally closed contact devices on ladder rungs are sometimes called ____ contacts or devices.

When control devices are connected in parallel, they form the Boolean "_______________" function.

The second device in the motor control ladder diagram run is the ____ pushbutton.

Three-wire motor control circuits are called three-wire, because there are three _______________ circuit wires between the motor starter and the control device(s).

Three-wire control circuit components may be either maintained contact or momentary contact, but the _______________ contact function is specific to three-wire control.

_______________ contacts are a normally-open set of contacts mounted on the contactor portion of the motor starter, and are actuated by the armature of the contactor unit.

When the ____ pushbutton is pressed, the control circuit power will pass through to the motor starter contactor control coil S1.

____ contact control devices change states when acted upon, but then return to their original state when released.

One of the other names of holding contacts is ____ contacts.

The ____ pushbutton will always be the first device off of L1, so that it has "master control" of the rung.

Three-wire motor control circuits have three control circuit wires between the motor starter and the control device(s).