Protective Functions - Fuji Electric FRENIC-HVAC User Manual

9.1 Protective Functions

The FRENIC-HVAC/AQUA series of inverters has various protective functions as listed below to
prevent the system from going down and reduce system downtime. The protective functions marked
with ● in the table are disabled by factory default. Enable them according to your needs.
The protective functions include, for example, the "heavy alarm" detection function which, upon
detection of an abnormal state, displays the alarm code on the LCD monitor and causes the inverter to
trip, the "light alarm" 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 content of the protective functions listed below and follow the
procedures given in Sections 9.2 and onwards for troubleshooting.
Protective function
"Heavy alarm"
detection
● "Light alarm"
detection
Stall prevention
●
Overload prevention
control
●
Automatic
deceleration
(Anti-regenerative control)
●
Deceleration
characteristics
(Excessive regenerative
energy proof braking
capability)
●
Reference loss
detection
Automatic lowering of
carrier frequency
● Dew condensation
prevention
Motor overload early
warning
●
Auto-reset
●
Forced stop
Surge protection
This function detects an abnormal state, displays the corresponding alarm
code, and causes the inverter to trip. The "heavy alarm" codes are
check-marked in the "Heavy alarm" object column in Table 9.1. For details
of each alarm code, see the corresponding item in the troubleshooting.
The inverter can store and display the last ten alarm codes and the date on
which they occurred (when realtime clock function enabled), and detailed
information on each relevant part for the past four alarms.
This function detects abnormal states, and allows operation to continue
without tripping the inverter while displaying and outputting warnings.
It is possible to define which abnormal states should be categorized as a
"light alarm". See the "light alarm" codes in Table 9.1.
See Section 9.3.2 for details on how to check and release light alarms.
When the output current exceeds the current limiter level (F44) during
acceleration/ deceleration or constant speed running, this function decreases
the output frequency and controls increases in output current to avoid an
overcurrent trip.
Before the inverter trips due to a heat sink overheat (OH1) or inverter
overload (OLU), this function decreases the output frequency to reduce the
load.
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.
During deceleration, this function increases the motor energy loss and
decreases the regenerative energy returned to avoid an overvoltage trip
(OV).
This function detects a reference frequency loss (due to a broken wire, etc.),
continues the inverter operation at the previously specified frequency, and
issues the "Command loss detected" signal REF OFF.
Before the inverter trips due to an abnormal ambient temperature or output
current, this function automatically lowers the carrier frequency to mitigate
inverter loss and avoid a trip.
Even when the inverter is in stopped state, this function feeds DC current
across the motor at certain intervals to raise the motor temperature and
prevent dew condensation.
When the inverter output current reaches the specified level, this function
issues the "Motor overload early warning" signal OL before the thermal
overload protection function causes the inverter to trip for motor protection.
When the inverter has stopped because of a trip, this function allows the
inverter to automatically reset alarms and restart itself. (The number of
retries and the latency between stop and reset can be specified.)
Upon receipt of the forced stop command STOP, this function interrupts the
run and other commands currently applied in order to forcedly decelerate the
inverter to a stop.
This function protects the inverter from a surge voltage invaded between
main circuit power lines and the ground.
9-1

9.1 Protective Functions

Description
Related
function
code
H98
H181
H182
H183
H184
F44
H70
H69
H76
H71
E65
H98
J21
E34
E35
H04
H05
H56
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