Mitsubishi Electric FR-A720-0.4K Instruction Manual page 368

Special operation and frequency control
(1) Load torque high speed frequency control setting
· Set "2 or 3" in Pr. 270 Stop-on contact/load torque high-speed frequency control selection.
· When operating with the load torque high speed frequency function selection signal (X19) on, the inverter
automatically changes the maximum frequency within the setting range of Pr. 4 Multi-speed setting (high speed) and
Pr. 5 according to the magnitude of the average current during the time to accelerate from 1/2 of the frequency set
in Pr. 5 Multi-speed setting (middle speed) to the frequency set in Pr. 5 .
· Set "19" in Pr. 178 to Pr. 189 (input terminal function selection) and assign the X19 signal function to the input terminal.
· Made valid only in the external operation mode.
· This control can be activated at every start.
Power running
Pr. 4
Pr. 5
1
Pr. 5
2
A
Current averaging range Current averaging range Current averaging range
Less than Less than Less than
Pr. 271 setting rated current Pr. 271 setting rated current Pr. 271 setting rated current
STF
ON
(STR)
ON
X19
(2) Operation of load torque high speed frequency control setting
· When the average current of the current averaging range (above chart A) during operation with the X19 signal on is
less than the "rated inverter current × Pr. 271 setting (%)", the maximum frequency automatically becomes the Pr. 4
Multi-speed setting (high speed) setting value.
· When the average current of the current averaging range (above chart B) during operation with the X19 signal on is
more than the "rated inverter current × Pr. 272 setting (%)", the maximum frequency automatically becomes the Pr.
5 Multi-speed setting (middle speed) setting value.
· The current averaging range can be set between 1/2 frequency of the Pr. 273 setting value and Pr. 273 set frequency.
CAUTION
· When the current averaging range includes the constant power range, the output current may become large in the constant
power range.
· When the average current value in the current averaging range is small, deceleration time becomes longer as the running
frequency increases.
· The maximum output frequency is 120Hz. The output frequency is 120Hz even when the setting is above 120Hz.
· The fast response current limit function is made invalid.
· Changing the terminal function using any of Pr. 178 to Pr. 189 may affect the other functions. Please make setting after
confirming the function of each terminal.
· The load torque high speed frequency function is made invalid in the following operation conditions.
PU operation (Pr. 79) , PU+external operation (Pr. 79) , JOG operation (JOG signal) , PID control function operation (X14 signal),
remote setting function operation (Pr. 59), orientation control function operation, multi-speed setting (RH, RM, RL signal ), 16 bit
digital input option (FR-A7AX)
· When the average current during acceleration is too small, it may be judged as regeneration and the maximum frequency
becomes the setting of Pr. 5.
When the load is light, the motor may suddenly accelerate to 120Hz maximum, causing hazard.
Securely provide mechanical interlock on the machine side to perform.
♦ Parameters referred to ♦
Pr. 4 to Pr. 6, Pr. 24 to Pr. 27 (multi-speed setting)
Pr. 59 Remote function selection
Pr. 79 Operation mode selection
Pr. 128 PID action selection
Pr. 178 to Pr. 189 (input terminal function selection)
358
Regenerating
B
Current averaging range Current averaging range Current averaging range
Pr. 272 setting rated current Pr. 272 setting rated current Pr. 272 setting rated current
or more or more or more
OFF ON
ON
OFF
CAUTION
Refer to page 161
Refer to page 165
Refer to page 298
Refer to page 344
Refer to page 222
Pr. 4
(60Hz)
Pr. 5
Time
(30Hz)
Pr. 271
(50%)
OFF
OFF
Pr. 272 Average current
(100%)
Value in parenthesis is initial value.