Mitsubishi Electric F700, Instruction Manual

Page: 258 / 341

249
Special operation and frequency control
4
PA
R
A
M
E
T
E
R
S
(2) To detect the regeneration status during deceleration faster (Pr. 884)
˜
As the regeneration avoidance function cannot respond to an abrupt voltage change by detection of the bus
voltage level, the ratio of bus voltage change is detected to stop deceleration if the bus voltage is less than
Pr. 883
Regeneration avoidance operation level .
Set that detectable bus voltage change ratio to
Pr. 884
as detection sensitivity.
Increasing the setting raises the detection sensitivity
(4) Regeneration avoidance function adjustment (Pr. 886)
˜
If the frequency becomes unstable during regeneration avoidance operation, decrease the setting of Pr. 886
Regeneration avoidance voltage gain . Reversely, if sudden regeneration causes an overvoltage fault, increase the
setting.
CAUTION
Too small setting (low detection sensitivity) will disable detection, and too large setting will turn on the regeneration avoidance
function if the bus voltage is varied by an input power change, etc.
(3) Limit regeneration avoidance operation frequency
(Pr. 885)
You can limit the output frequency compensated for (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. If the frequency increased by regeneration avoidance
function exceeds the limit value during deceleration, the limit value
is held until the output frequency falls to 1/2 of
Pr. 885 .
˜
When the frequency increased by regeneration avoidance function
has reached
Pr. 1 Maximum frequency , it is limited to the maximum
frequency.
˜
Pr. 885 is set to "9999", regeneration avoidance function operation
frequency setting is invalid.
CAUTION
˜
When regeneration avoidance operation is performed, (overvoltage stall) is displayed and the OL signal is output.
˜
When regeneration avoidance operation is performed, stall prevention is also activated.
˜
The regeneration avoidance function cannot shorten the actual deceleration time taken to stop the motor. The actual
deceleration time depends on the regenerative energy consumption capability. When shortening the deceleration time,
consider using the regeneration unit (FR-BU2, BU, FR-BU, MT-BU5, FR-CV, FR-HC, MT-HC) to consume regenerative energy
at constant speed.
˜
When using a regeneration unit (FR-BU2, BU, FR-BU, MT-BU5, FR-CV, FR-HC, MT-HC) to consume regenerative energy at
constant speed, set
Pr. 882 = "0 (initial value)" (Regenerative avoidance function invalid). When using the regeneration unit, etc.
to consume regenerative energy at deceleration, set Pr. 882 = "2" (regeneration avoidance function valid only at a constant
speed).
˜
When regeneration avoidance operation is performed, the OL signal output item of
Pr. 156
also becomes the target of
(overvoltage stall). Pr. 157 OL signal output timer also becomes the target of (overvoltage stall).
i
Parameters referred to
i
Pr. 1 Maximum frequency Refer to page 76
Pr. 8 Deceleration time Refer to page 90
Pr. 22 Stall prevention operation level Refer to page 70
Limit level
Time
Pr.885
Output frequency (Hz)
Pr.885/2
Output
frequency(Hz)