Motor Controllers AC Variable Frequency Drives
RVBS
Specifications are subjected to change without notice.10/08/2021
37
4.4.4
Electronic motor overload
F09 through F11 specify the thermal characteristics of the motor for its electronic thermal overload protection
that is used to detect overload conditions of the motor. F09 selects the motor cooling mechanism to specify its
characteristics, F10 specifies the overload detection current, and F11 specifies the thermal time constant.
➢
To disable the electronic thermal overload protection, set function code F10 to "0.00."
-
Motor characteristics (F09)
F09 selects the cooling mechanism of the motor-- shaft-driven or separately powered cooling fan.
Data for F09
Function
1
For a general-purpose motor with shaft-driven cooling fan.
(The cooling effect will decrease in low frequency operation.)
2
For an inverter-driven motor with separately powered cooling fan.
(The cooling effect will be kept constant regardless of the output frequency.)
The figure below shows operating characteristics of the electronic thermal overload protection when F09 = 1.
The characteristic factors
α1 through α3 as well as their corresponding switching frequencies f2 and f3 vary
with the characteristics of the motor. Also, Actual Output Current (Continuous) means the detection level of
output current that electronic thermal overload protection activates above.
< Cooling characteristics of motor with shaft-driven cooling fan >
The tables below list the factors determined by the motor capacity (P01).
Nominal
applied motor
(kW)
Thermal time constant
(Factory default)
Reference current for
setting the thermal time
constant (Imax)
Output frequency for motor
characteristic factor
Characteristic factor
f2
f3
1
2
3
0.1 to 0.75
5 min
Allowable continuous
current 150%
5 Hz
7 Hz
75%
85%
100%
When F09 = 2, the cooling effect is not decreased by the output frequency so that the overload detection level
is a constant value without reduction (F10).
-
Overload detection level (F10)
