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Free-electronic thermal reduction factor
Example. 3-phase 200-V, 1.5 kW (Heavy load rating 8 A)
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When b012 = 8 [A], b015 = 1.5 [Hz], b016 = 4 [A]
The basic reduction factor is: 0.9 at 1.5 Hz. The free-electronic thermal reduction factor is:
b016/b012 = 0.5. The final reduction factor is: 0.9 0.5 = x0.45.
The reference value (100%) of basic characteristics for electronic thermal function is: 8 [A]
0.45 = 3.6 [A].
Therefore, 150% of the basic characteristics value is: 5.4 [A] for 60 s.
7-8-2 Motor Electronic Thermal Function
Setting the Motor Electronic Thermal Selection (b910) to 01 to 03 separates the inverter from the motor
electronic thermal function, which allows you to set the electronic thermal characteristics according to
the motor in use.
To enable the motor electronic thermal function and parameters b911 to b913, set the Motor Electronic
Thermal Selection (b910) to 01 to 03.
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You can set electronic thermal characteristics according to the thermal time constant of the motor in
use.
For the thermal time constant of your motor, contact the motor manufacturer.
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In the 1st/2nd Electronic Thermal Level (b012/b212), set the rated current of your motor.
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In the 1st/2nd Electronic Thermal Characteristics Selection (b013/b213), set the characteristics of
your motor.
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In the Motor Electronic Thermal Selection (b910), select an appropriate setting for your motor from 01
to 03.
The recommended setting is 03 (Enabled: b912 time parameter subtraction). The settings 01
(Enabled: Fixed subtraction rate), 02 (Enabled: b911 subtraction rate), and 03 (Enabled: b912 time
parameter subtraction) are described later in this section.
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In the Motor Electronic Thermal Subtraction Ratio (b911), set a subtraction rate with an allowance of
approximately 40% added to the thermal time constant of your motor when b910 is set to 02.
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In the Motor Electronic Thermal Subtraction Time Constant (b912), set a subtraction time constant
with an allowance of approximately 20% added to the thermal time constant of your motor when b910
is set to 03.
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In the Motor Electronic Thermal Integration Gain (b913), set an electronic thermal integration gain
when b910 is set to 01 to 03. When b913 is set to 100%, the overload capacity is 150% of the basic
characteristics of the electric thermal function for 1 minute.
For details on the basic characteristics of the electronic thermal function, refer to 5-3-2 Electronic
Thermal Function on page 5-15.
Decreasing the b913 value prolongs the basic characteristics detection time, while increasing the
value shortens the basic characteristics detection time.
Set an optimal value based on the time during which 150% of the overload capacity of your motor is
applied.
However, be sure to provide a safety margin of 20 to 50%.
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