HW7 Chapter 7

Timers are used to activate or de-activate a device after a preset interval of time.

• True

• False

With most timers the time delay period is fixed and can not be varied.

• True

• False

3. contacts are controlled directly by the timer coil, as in a general-purpose control relay.

• timed
• NO

• instantaneous
• NC

When a relay timer coil is de-energized, do the timed contacts always return instantaneously to their normal state?

• True

• False

Which of the following symbols represents a normally open timed closed contact?

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• 
• 
• 

Which of the following symbols represents a normally closed timed open contact?

• 
• 
• 
• 

The timed relay contact shown is designed to operate so that:

• when the relay coil is energized, there is a time delay in closing

• when the relay coil is energized, there is a time delay in opening

• when the relay coil is de-energized, there is a time delay in closing

• when the relay coil is de-energized, there is a time delay in opening

The timing diagram shown is that of an:

• on-delay timer circuit (NOTC contact)

• on-delay timer circuit (NCTO contact)

• off-delay timer circuit (NCTC contact)

• off-delay timer circuit (NOTO contact)

In the circuit shown, the light will stay off:

• as long as S1 is closed

• for 10 seconds after coil TD is energized

• for 10 seconds after coil TD is de-energized

• both a and c

For the program shown, the pilot light will be:

• on at all times

• off at all times

• switched on 15 s after the switch has been actuated from the open to the closed position

• switched off 15 s after the switch has been actuated from the on to off position