6. Function Description
6-44
6.4.6 Electronic thermal (motor
2
) selection
These functions are required when the motor should be protected against the overheat without installing the thermal
relay between the inverter and the motor. If electronic thermal protection is ON, the inverter blocks the IGBT gating
signals and issues the trip message.
Code LCD display Description Setting range Unit Factory setting
FUN_54 ETH Select Electronic thermal selection
No
Yes
No
FUN_55 ETH 1 Min
Electronic thermal level
for 1 minute
FUN_56 ~ 200 % 150
FUN_56 ETH Cont
Electronic thermal level
for continuous
50 ~ FUN_55
(up to 150%)
% 100
PAR_09 Cooling Mtd Motor cooling method
Self-cool
Forced-cool
Forced-cool
Electronic thermal protection level is set in % based on the ‘Motor rated current’ at PAR_22. ‘1 min.level of
electronic thermal’ at FUN_55 is the current level which should be referred to when the motor is operated for a
minute and the motor is estimated to be overheated. ‘Continuous level of electronic thermal’ at FUN_56 is the
current level which should be referred to when the motor is operated continuously and the motor is estimated to be in
thermal equilibrium. Continuous level is set to the motor rated current (100%) and should be less than ‘1 min.level of
electronic thermal’ at FUN_55. PAR_09 ‘Cooling type’ should be set correctly to ensure the proper electronic thermal
protection.
z Self-cool : This should be set when cooling fan mounted on the motor shaft is used for cooling. The
cooling performance is greatly reduced when the motor is operated at the low speed. Compared to high
speed region, the motor is rapidly overheated at the low speed region even if the same current flows into it.
So like the graph below, according to frequency, the allowable continous current value of ‘Continuous
level of electronic thermal’ of FUN_56 is reduced and electronic thermal function starts operating.
z
Forced-cool : This should be set when the cooling fan is powered by the separate power supply.
‘Continuous level of electronic thermal’ at FUN_56, which is allowable continuous current is applied,
regadless of the operating frequency.
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