WorksheetsLesson 8 PLC TIMER
Total questions: 20
Worksheet time: 10mins
What devices are used to create delays in industrial control systems?
Pressure switches and flow sensors
Variable frequency drives and PLCs
Magnetic contactors and overload protectors
Time delay relays and solid-state timers
What happens to the contacts in an on-delay timing relay when the coil is turned on?
They keep opening and closing during the delay
They make a quick noise and then stop
They stay in their normal position until the delay is over
They change position right away when the coil is turned on
What part controls the instant contacts in a relay?
External control switch
Magnetic field of the operating coil
Time adjustment mechanism
Timed contact cam assembly
What happens to the timed contacts when the coil is turned off?
They stay locked until the coil is turned back on
They start a delay before returning
They remain in the last position until reset
They go back to normal immediately
What type of relay contact should be used to start a motor after a delay when a start signal is given?
Instant NO contact from the relay
Delayed NO contact after a set time
Delayed NC contact that skips the wait
Instant NC contact in line
Which type of contact closes after a delay when the relay coil is powered, but is open when it is not powered?
NOTC on-delay normally open contact
NCTO on-delay normally closed contact
NOTO off-delay normally open contact
NCTC off-delay normally closed contact
Why might engineers pick a 0.01 s time base instead of 1 s?
To keep outputs on for a longer time
To use less memory for saved values
To have better timing accuracy and shorter waits
To stop ACC from ever matching PRE
What does an on-delay timer do in ladder logic?
Turns on the output after a set time when the rung is true
Turns on the output right away when the rung is true
Turns off the output after a set time when the rung is true
Switches the output on and off repeatedly while the rung is true
In Allen-Bradley PLCs, a timer uses three words in the data table. Which set lists them correctly?
Preset, interval, elapsed
Status, preset, interval
Control, preset, accumulated
Control, scaling, status
Which control bit shows that the timer is active because the conditions are met?
TT bit shows active timer
DN bit shows active timer
ACC word shows active timer
EN bit shows active timer
When an on-delay timer is running but not finished, which bit is usually true?
EN bit is false while it is running
ACC word resets while it is running
DN bit is true while it is running
TT bit is true while it is running
What happens when the set time is reached for an on-delay timer?
The ACC word becomes true
The DN bit becomes true
The TT bit becomes true
The EN bit becomes true
When is the EN bit not true?
The timer rung is not true
The timer has reached its set time
The timer value is increasing
The timer TT bit is true
What happens to the control bits when an on-delay timer is active?
Timer off: EN true, TT false, DN true
Timer off and counting: EN true, TT true, DN false
Timer on: EN false, TT true, DN true
Timer on and counting: EN true, TT true, DN false
What word in the data table shows how much time has passed on the timer?
Accumulated word shows elapsed time
Control word shows elapsed time
Status word shows elapsed time
Preset word shows elapsed time
In a TON instruction, when does the timer output turn ON?
As soon as the input is true
After the set delay time is over
When the EN bit is false
When the TT bit goes back to false
What does the DN bit do when the timer finishes counting in an on-delay timer?
It goes back to zero
It turns true
It switches between true and false
It stays false until the next time
What type of timer is used to keep a motor running for a short time after it gets a stop signal?
Instant timer
Off-delay timer
Pulsing timer
On-delay timer
Which bit shows that the timer is running?
TT bit
DN bit
EN bit
ACC word
What is the primary purpose of using a timer in a control system?
To increase the power supply
To monitor temperature changes
To create delays for process control
To measure the speed of the motor
