6.1 Protective Functions
6-1
6.1 Protective Functions
In order to prevent the system going down or to shorten recovery time, FRENIC-MEGA is equipped with various
protective functions shown in Table 6.1-1 below. The protective functions marked with an asterisk (*) in the table
are disabled by factory default.
Enable them according to your needs.
The protective functions include, for example, the “Alarm” detection function which, upon detection of an abnormal
state, displays the alarm code on the LED monitor and causes the inverter to trip, the “Warning” detection function
which displays the alarm code but lets the inverter continue the current operation, and other warning signal output
functions.
If any problem arises, understand the protective functions listed below and follow the procedures given in sections
6.2 and onwards for troubleshooting.
Table 6.1-1 Abnormal state detection (alarms/warnings)
This function detects an abnormal state, displays the corresponding
alarm code on the keypad, and causes the inverter to trip.
Refer to “6.3.1 Alarm code list” for alarm codes, and refer to “6.3.2
Causes, checks and measures of alarms” for details on the alarm
content.
The inverter retains the last four alarm codes and their factors together
with their running information applied when the alarm occurred, so it can
display them.
All abnormal conditions are detected, and if a minor abnormality is
detected, a warning code is displayed, and operation continues without
tripping the inverter.
The warning display operation can be selected with the warning
selection (function codes H81, H82, H83).
When the output current exceeds the current limiter level (function code
F44) during acceleration/ deceleration or constant speed running, this
function decreases the output frequency to avoid an overcurrent trip.
Overload prevention
control*
Before the inverter trips due to a cooling fin overheat (0H1) or inverter
overload (0lU), this function decreases the output frequency of the
inverter to reduce the load.
Anti-regenerative
control*
If regenerative energy returned exceeds the inverter's braking capability,
this function automatically increases the deceleration time or controls
the output frequency to avoid an overvoltage trip.
Deceleration
characteristics*
(Improvement of
braking performance)
During deceleration, this function increases the motor energy loss and
decreases the regenerative energy returned to avoid an overvoltage
trip.
Reference loss
detection*
This function detects a frequency reference loss (due to a broken wire,
etc.), issues the alarm, and continues the inverter operation at the
specified frequency.
Automatic lowering of
carrier frequency
Before the inverter trips due to an abnormal surrounding temperature or
output current, this function automatically lowers the carrier frequency to
avoid a trip.
Motor overload early
warning*
When the inverter output current has exceeded the specified level, this
function issues the “Motor overload early warning” signal before the
thermal overload protection function causes the inverter to trip for motor
protection (only for the 1st motor).
When the inverter has stopped because of a trip, this function allows the
inverter to automatically reset and restart itself.
The number of retries and the latency between stop and reset can be
specified.
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