LS ELECTRIC SV-iS7 Series, User Manual

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Using Protection Features
327
Code Description
PRT-20
OL Trip Select
Select the inverter protective action in the event of an overload fault trip.
Setting Function
0 None No protective action is taken.
1 Free-Run
In the event of an overload fault, inverter output is
blocked and the motor will free-run due to inertia.
3 Dec If a fault trip occurs, the motor decelerates and stops.
PRT-21 OL Trip
Level,
PRT-22 OL Trip Time
When the current supplied to the motor is greater than the preset value of
the overload trip level (OL Trip Level) and continues to be supplied during
the overload trip time (OL Trip Time), the inverter output is either blocked
according to the preset mode from PRT-17 or slows to a stop after
deceleration.
Note
Overload warnings warn of an overload before an overload fault trip occurs. The overload warning
signal may not work in an overload fault trip situation, if the overload warning level (OL Warn Level)
and the overload warning time (OL Warn Time) are set higher than the overload trip level (OL Trip
Level) and the overload trip time (OL Trip Time).
10.1.3 Stall Prevention and Flux Braking
The stall prevention function is a protective function that prevents motors from stalling due to
overloads. If a motor stall occurs due to an overload, the inverter operation frequency is
adjusted automatically. When a stall is caused by overload, high currents induced in the motor
may cause motor overheating or damage the motor and interrupt operation of the motor-
driven devices.
In this case, the motor decelerates with optimum deceleration without a braking resistor by
using flux braking. If the deceleration time is too short, an over voltage fault trip may occur
because of regenerative energy from the motor. The flux braking makes the motor use
regenerate energy, therefore optimum deceleration is available without over voltage fault trip.