
5-30
Nominal Applied Motor and Characteristic Factors when P99 (Motor 1 Selection) = 1 or 3
Output frequency for
motor characteristic factor
Characteristic
factor
Nominal
applied motor
(kW)
Thermal time
constant
τ
(Factory default)
Reference current
for setting the
thermal time
constant (Imax)
f2 f3
α
1
α
2
α
3
0.1 to 22
5 min
Base
frequency
×
33%
69% 90% 90%
30 10
min
Allowable
continuous current
×
150%
Base
frequency
×
33%
Base
frequency
×
83%
54% 85% 95%
When F10 = 2, the cooling effect is not decreased by the output frequency so that the
overload detection level is a constant value without reduction (F11).
Overload detection level (F11)
F11 specifies the detection level (in amperes) at which the electronic thermal overload
protection becomes activated.
In general, set F11 to the rated current of motor when driven at the base frequency (i.e. 1.0 to
1.1 multiple of the rated current of motor 1 (P03)). To disable the electronic thermal overload
protection, set F11 to "0.00: Disable."
Thermal time constant (F12)
F12 specifies the thermal time constant of the motor. If the current of 150% of the overload
detection level specified by F11 flows 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 including Fuji motors is approx. 5 minutes by factory
default.
- Data setting range: 0.5 to 75.0 (minutes) in increments of 0.1 (minute)
(Example) When the F12 data is set at "5.0" (5 minutes)
As shown below, the electronic thermal overload protection is activated to detect an alarm
condition (alarm code
0l1
) when the output current of 150% of the overload detection level
(specified by F11) flows 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
allowable continuous drive current (100%) until it reaches 150% of the overload detection
level.