Basic Programming 5 - 18
If L2-01=1, the Drive restarts without the UV1 fault if power is returned within the time specified in L2-02, the Momentary
Power Loss Ride-thru Time. During the power loss but before the fault trip, the digital operator will display a UV alarm. If
L2-02 is set for a time longer than the control power supply can be sustained, a UV1 fault will not occur and the Drive restarts
upon the return of AC power. The time that the control power supply can be maintained varies with Drive size. The larger the
Drive is, the greater the potential ride-thru time.
If L2-01=2, the Drive ignores L2-02 and attempts a restart as long as the control power supply is still able to maintain a mini-
mal voltage level. In effect, setting L2-01=2 is programming the Drive for maximum Power Loss Ride-thru. An equivalent
setting is L2-01=1 with L2-02 set to a time longer than the control power supply can be maintained after power is lost.
Note: The run command must be held during power loss for any power loss ride-thru capability to be possible. It is for this
reason that 3-wire control is not recommended for use with the Momentary Power Loss function.
Speed Command Loss Detection
L4-05 Frequency Reference Loss Detection Selection
L4-06 Frequency Reference at Loss of Frequency Reference
The Drive can be configured to compensate for the loss of its external speed command. An external speed command is
considered lost if it drops 90% of its value in 400mS or less.
Fig 5.16 Loss of Frequency Reference Response Chart
To enable Frequency loss detection, set L4-05=1. If Frequency Reference Loss Detection is enabled and the reference is lost,
the Drive continues to operate at the speed commanded by parameter L4-06. Once the speed command returns, the Drive once
again follows the speed command.
Only when L4-05=1, does setting H2-01/H2-02=C configure a digital output as a Frequency Reference Loss warning.
Auto Restart
L5-01 Number of Auto Restart Attempts
L5-03 Maximum Restart Time After Fault
All faults will cause the Drive to stop operating the motor. For some faults, it is possible to configure the Drive to attempt a
restart. After the fault occurs, the Drive baseblocks for L2-03 seconds. After the baseblock is removed, the Drive attempts to
restart. If the restart is successful, the Drive performs a Speed Search from set speed command and the Auto Restart Attempts
count is increased by 1. If the restart fails (or is not attempted due to a continuing fault condition, e.g. an OV fault) the Drive
waits L5-03 seconds before attempting another restart.
Frequency
Reference
Output
Fre
uenc
T
-
=
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