Hitachi America, Ltd.
EN-021302-1
ENGINEERING NOTE
SUBJECT: Parameter A85, Operation Mode Selection
AFFECTED MODELS: L300P and SJ300
The manuals for the SJ300 and L300P show three settings for Parameter A85.
This is ONLY correct for the SJ300.
There are only TWO settings for the L300P: “00” for Normal Operation, and “01”
for Energy-Saving Operation. The latter setting seeks to adjust the output voltage
at any given output frequency to minimize the motor current, and hence power
consumption at that speed. This function only acts at constant speed – not during
acceleration or deceleration.
Optimal Accel/Decel Operation (SJ300 ONLY)
In addition to “Normal” and “Energy Saving” modes, the SJ300 offers a third
setting option, “02” for Optimal Accel/Decel Operation. This function is an
implementation of a “fuzzy logic” algorithm. In real time, the function
automatically adjusts the acceleration and deceleration times in response to
changes in load or inertia, to take advantage of the maximum output current
capability of the inverter. In general, this mode will allow for the shortest accel
and decel times based on the actual load conditions. The function continuously
monitors output current and DC bus voltage to ensure that their respective trip
levels are not reached. In this mode, the settings of acceleration and deceleration
times (F002 and F003) are disregarded.
The acceleration time is controlled to maintain output current below the level set
by the Overload Restriction Function if enabled (Parameters B21/B24, B22/B25,
and B23/B26). If Overload Restriction is not enabled, then the current limit used
is 150% of the inverter’s rated output current.
The deceleration time is controlled so that the output current is maintained below
150% of the inverters rated current, AND the DC bus voltage is maintained below
the OV Trip level (358V or 770V).
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EN-021302-1
Notes and Precautions
1. Do not use this setting (A85 = 02) on a machine where a constant
acceleration and/or deceleration time is desired.
2. Do not use this setting (A85 = 02) if the load inertia exceeds about 20 times
the motor shaft inertia.
3. Do not use this setting (A85 = 02) if the inverter will increase and decrease
speed frequently, as nuisance trips may occur.
4. Do not use this setting (A85 = 02) if internal or external regenerative braking
is being used.
5. Do not use this setting (A85 = 02) with any of the Vector Control modes
(A44 = 03, 04, or 05). This function is ONLY compatible with V/F Control
modes (A44 = 00, 01, or 02).
6. If the load exceeds the rating of the inverter, the acceleration time may be
increased.
7. If using a motor the capacity of which is one size smaller than the inverter
rating, enable the Overload Restriction function (B21/B24) and set the
Overload Restriction Level (B22/B25) to 1.5 times the motor nameplate
current.
8. Be aware that the acceleration and deceleration times will vary depending on
the actual load conditions that exist during each individual operation of the
inverter.
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