Mitsubishi Electric FR-A500 Instruction Manual page 203

Operation Panel
Indication
Name
Description
Check point
Corrective action
Operation Panel
Indication
Name
Description
Check point
Corrective action
Note: 1. Resetting the inverter initializes the internal heat integrating data of the electronic thermal relay
function.
Operation Panel
Indication
Name
Description
Check point
Corrective action
Note: 2. When an instantaneous power failure occurs, the alarm display and alarm output are not provided,
but the inverter performs protective operation to prevent a fault from occurring in itself. In some
operating status (load size, acceleration/deceleration time setting, etc.), overcurrent or other
protection may be activated upon power restoration.
E.THM
Motor overload shut-off (electronic thermal relay function) (Note 1)
The electronic overcurrent protection in the inverter detects motor overheat due to
overload or reduced cooling capability during constant-speed operation. When 85%
of the preset value is reached, pre-alarm (TH indication) occurs. When the specified
value is reached, the protective circuit is activated to stop the inverter output. When
a special motor such as a multi-pole motor or two or more motors are run, provide a
thermal relay on the inverter output side since the motor(s) cannot be protected by
the electronic overcurrent protection.
Check the motor for use under overload.
• Reduce the load weight.
• For a constant-torque motor, change the Pr. 71 setting to the constant-torque
motor setting.
E.THT
Inverter overload shut-off (electronic thermal relay function) (Note 1)
If a current of more than 150% of the rated output current flows and overcurrent
shut-off does not occur (200% or less), inverse-time characteristics cause the
electronic overcurrent protection to be activated to stop the inverter output in order
to protect the output transistors.
(Overload immunity 150%, 60s.)
Check the motor for use under overload.
Reduce the load weight.
E.IPF
Instantaneous power failure protection (Note 2)
If a power failure occurs for longer than 15ms (this also applies to inverter input
shut-off), the instantaneous power failure protective function is activated to stop the
inverter output in order to prevent the control circuit from malfunctioning. At this
time, the alarm warning output contacts open (across terminals B-C) and close
(across terminals A-C). (Note 2) If a power failure persists for longer than 100ms,
the alarm warning output is not provided, and the inverter restarts if the start signal
is on upon power restoration. (The inverter continues operating if an instantaneous
power failure is within 15ms.)
Find the cause of instantaneous power failure occurrence.
• Remedy the instantaneous power failure.
• Prepare a backup power supply for instantaneous power failure.
• Set the function of automatic restart after instantaneous power failure. (Refer to
page 94.)
PROTECTIVE FUNCTIONS
FR-PU04
FR-PU04
FR-PU04
194
Motor Ovrload
Inv. Overload
Inst. Pwr. Loss