Mitsubishi Electric FR-D720-0.4K Instruction Manual page 228

Special operation and frequency control
REMARKS
The acceleration/deceleration ramp while the regeneration avoidance function is operating changes depending on the
regeneration load.
The DC bus voltage of the inverter is about
input voltage.)
When the input voltage is 100VAC, bus voltage is approximately 283VDC.
When the input voltage is 220VAC, bus voltage is approximately 311VDC.
When the input voltage is 440VAC, bus voltage is approximately 622VDC.
However, it varies with the input power supply waveform.
The Pr. 883 setting should be kept higher than the DC bus voltage level. Otherwise, the regeneration avoidance function is
always ON even in the non-regeneration status and the frequency increases.
While overvoltage stall (
function is always ON (Pr. 882 = 1) or activated only during a constant speed (Pr. 882 = 2) and increases the frequency
according to the regeneration amount.
Limit level
Pr. 885
(3) Regeneration avoidance function adjustment (Pr. 665, Pr. 886)
If the frequency becomes instable during regeneration avoidance operation, decrease the setting of Pr. 886 Regeneration
avoidance voltage gain. Reversely, if sudden regeneration causes an overvoltage alarm, increase the setting.
When vibration is not suppressed by decreasing the Pr. 886 setting, set a smaller value in Pr. 665 Regeneration avoidance
frequency gain.
NOTE
When regeneration avoidance operation is performed,
output. Set the operation pattern at an OL signal output using Pr. 156 Stall prevention operation selection. Set the output
timing of the OL signal using Pr. 157 OL signal output timer.
When regeneration avoidance operation is performed, stall prevention is also activated at the same time.
The regeneration avoidance function cannot shorten the actual deceleration time taken to stop the motor. The actual
deceleration time depends on the regeneration energy consumption capability. To shorten the deceleration time,
consider using the regeneration unit (FR-BU2, FR-CV, FR-HC) and brake resistor (MRS type, MYS type, FR-ABR etc.)
to consume regeneration energy at constant speed.
When using the regeneration unit (FR-BU2, FR-CV, FR-HC) and brake resistor (MRS type, MYS type, FR-ABR etc.), set
Pr. 882 to "0 (initial value)" (regeneration avoidance function invalid). When using the regeneration unit, etc. to
consume regeneration energy at deceleration, set Pr. 882 to "2" (regeneration avoidance function valid only at a
constant speed).
Parameters referred to
Pr. 1 Maximum frequency
Pr. 8 Deceleration time
Pr. 22 Stall prevention operation level
226
2
) is activated only during deceleration and stops the output frequency, the regeneration avoidance
(2)
You can limit the output frequency compensated (increased) by the
regeneration avoidance function.
The frequency is limited to the output frequency (frequency prior to
regeneration avoidance operation) + Pr. 885 Regeneration avoidance
compensation frequency limit value during acceleration or constant speed.
Output frequency (Hz)
If the regeneration avoidance frequency exceeds the limit value during
deceleration, the limit value is held until the output frequency falls to 1/2
of Pr. 885.
Pr. 885/2
When the frequency increased by regeneration avoidance function has
Time
reached Pr. 1 Maximum frequency, it is limited to the maximum frequency.
When Pr. 885 is set to "9999", regeneration avoidance function operation
frequency setting is invalid.
Refer to page 84
Refer to page 97
Refer to page 80
times of normal input voltage. (For 100V class, twice the amount of the power
Limit regeneration avoidance operation frequency (Pr. 885)
(overvoltage stall) is displayed and the OL signal is