Operation
38
Auto Reset Timing Diagrams (continued)
Fig 5.6.2 Auto Reset - Two Wire - Control Supply Loss
The timing diagrams show the auto reset with a maintained two wire control system
The fault shown is a 3-phase supply loss
and
Control supply loss
The 3-Phase power and control supply are re-established (after the 2nd attempt) before the Reset Attempts counter is depleted
This assumes the start signal is maintained, if it is removed the Auto Reset terminates
Once power has been re-established there are no further outages and the counters are reset after the trip free time.
3-Phase Supply voltage
Control Supply
Start / Stop Input
Reset Input
(1)
Fault Relay
Restart Pending Relay
Imotor
Internal Reset
Reset Attempts PNU = 4
t0
t1
t2
t3
t4
t5
t6
t7
t8
t9
t10
Sequence of events
User Parameters (R/W)
Monitor Parameters (R/O)
t0 3 phase supply applied
PNU
Range
Default
PNU
Range
t1 Start signal applied, motor starts
t2 Motor reaches full voltage
Auto Reset
Off / On
Off
A
uto
R
eset Pending
0-1
t3 3 phase supply removed
Reset Delay
0-7200s
0s
A
uto
R
eset Exceeded
0-1
t5 Reset delay = 0 Restart Attempt =3
Reset Attempts
0-10
0
A
uto
R
eset Delay Remaining
0-7200s
t7 Reset delay = 0 Restart Attempt = 2
Reset Trips
All resettable trips -
A
uto
R
eset Attempts Remaining
0-10
t8 3-Phase re-established
Trip Free Time
0-7200s
600s
A
uto
R
eset Trip Free Time Remaining
0-7200s
Start signal must still be applied
If it has been removed Auto Reset feature re-initialises
Notes
If the trip is reset the Auto Reset feature re-initialises
The Starter is powered down between t3 and t8 ( yellow shaded region)
t9 Reset delay = 0 Restart Attempt = 1
During this time controller is unable to make the calculations in real time
t10 Trip Free Delay = 0 Restart Attempt = 4
To overcome this the calculations are made retrospectively at time t8
The Start Signal must be maintained, if it is not the Auto Restart will be terminated
For Two Wire control reset occurs automatically when the start signal changes state from low to high, reset shown is programmable reset input
(1)
If the time to re-establish the power exceeds (Reset Delay x Reset Attempts) to Auto Reset terminates
Reset Attempts = 4
Reset Delay
Reset Delay
Reset Delay
Trip Free Time
Reset Attempts = 4
Reset Attempts = 3 Reset Attempts = 2
Reset Attempts = 1
