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8.1 Electronic Protection
When a trip occurs, the inverter will remain
disabled (provided that the restart function is
not in use, refer to Functions 13 and 14) until
the conditions that caused the trip are removed
and the inverter is reset by pressing the
PRG/RESET key or applying a reset com-
mand input at terminal RST.
NOTE If the electronic protection acts to trip
the inverter, investigate the cause of the
trouble by using the appropriate flow dia-
gram on the following pages. If you cannot
identify and correct the problem in this
way, or if you think the inverter may have
been damaged, please consult IMO
Precision Controls Ltd.
8.2 Trip Alarm Functions
All protective functions cause a trip code to be
displayed on the 7-segment LEDs panel.
All protective functions operate the internal
trip/alarm relay to close circuit (30A)-(30C)
and open circuit (30B)-(30C).
Output terminal Y1E can be used to signal
externally that the inverter has tripped on
undervoltage. Refer to Function 54.
Effects of a trip
• Inverter output stops
• Motor coasts to rest
• Trip code displayed and retained in memory
• Alarm relay change of state
NOTES
1 Alarm signal holding
If the power supply to the inverter is
switched off automatically or otherwise
after a protective function has operated, the
internal control power supply is lost and
the outputs at the alarm relay (30A/B/C)
and terminal Y1E are lost also.
2 Trip code memory
Trip codes of the four last trips are stored
in memory and are not affected by loss of
the power supply.
8.3 Trip Alarm Codes
OC1 Overcurrent trip during acceleration
OC2 Overcurrent trip during deceleration
OC3 Overcurrent trip at steady speed
Protects the inverter against momentary over-
current, short circuits or earth faults occurring
internally and in the motor circuit.
OLU Overload trip
Protects the inverter against overloading of the
inverter output devices (IGBTs).
OL Overload trip
Electronic thermal overload. Protects a stan-
dard 4-pole motor against overload.
OU1 Overvoltage trip during acceleration
OU2 Overvoltage trip during deceleration
OU3 Overvoltage trip at steady speed
Operates if the DC bus voltage exceeds the
overvoltage detection level because of regener-
ation. Does not operate or protect against
excessive supply input voltage.
OH1 Inverter overtemperature trip
Protects the inverter against overheating
caused by overloading, high ambient tempera-
ture, or cooling fan failure.
OH2 External alarm input trip
Operates when a trip command signal is input
at terminal THR.
LU Undervoltage trip
Trips the inverter if the supply voltage falls
below 165V for 1-phase inverters (310V for
3-phase inverters).
The inverter is designed to ‘ride through’ if
the voltage dip is momentary (≤15ms at full
‘motoring’ load). However, if the load is of
high inertia, the ride-through time could be
substantially greater. For further information
please consult IMO Precision Controls Ltd.
Er1 Memory error
Er2 Keypad communication error
Er3 CPU error
Er4 Option card checksum error
Er5 Serial communications link error
Er7 Error during auto-tuning
8 Troubleshooting
WARNING The inverter may restart auto-
matically after an overcurrent or overvoltage
trip. Refer to Functions 13 and 14.
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