4-42
Nominal Applied Motor and Characteristic Factors when P99 (Motor 1 Selection) = 1 or 3
Nominal applied
motor
HP
Thermal time
constant
(Factory default)
Reference current
for setting the
thermal time
constant (Imax)
Output frequency for
motor characteristic factor
Characteristic
factor (%)
f
2
f
3
1
2
3
0.25 to 30
5 min
Allowable
continuous current
150%
Base
frequency
33%
Base
frequency
33%
69
90
90
40 to 60
10 min
Base
frequency
83%
54
85
95
75 to 125
51
95
95
150 or above
53
85
90
If F10 is set to "2," changes of the output frequency do not affect the cooling effect. Therefore, the overload
detection level (F11) remains constant.
Overload detection level (F11)
Data setting range: 1 to 135% of the rated current (allowable continuous drive current) of the inverter
In general, set the F11 data to the allowable continuous current of motor when driven at the base frequency (i.e.
1.0 to 1.1 times of the rated current of the motor.)
To disable the electronic thermal overload protection, set the F11 data to "0.00."
Thermal time constant (F12)
Data setting range: 0.5 to 75.0 (minutes)
F12 specifies the thermal time constant of the motor. If the current of 150% of the overload detection level
specified by F11 is attained for the time specified by F12, the electronic thermal overload protection becomes
activated to detect the motor overload. The thermal time constant for general-purpose motors is approx. 5 minutes
for motors of 30 HP or below and 10 minutes for motors of 40 HP or above by factory default.
(Example) When the F12 data is set at 5 minutes
As shown below, the electronic thermal overload protection is activated to detect an alarm condition (alarm code
) when the output current of 150% of the overload detection level (specified by F11) is attained for 5 minutes,
and 120% for approx. 12.5 minutes.
The actual time required for issuing a motor overload alarm tends to be shorter than the specified value, taking
into account the time period from when the output current exceeds the rated current (100%) until it reaches 150%
of the overload detection level.
Example of Operating Characteristics