Speed Search Operation Setting Details
Select a speed search type.
The speed search is carried out as it controls the inverter
output current during idling below the CON-72 (SS Sup-
Current) parameter setting. Use when the direction of the
idling motor and the direction of operation command at
restart are the same. A stable speed search function can
be performed at about 10 Hz or lower. However, if the
direction of the idling motor and the direction of the start
command at restart are different, the speed search does
not produce a satisfactory result. The direction of the
idling motor cannot be established.
The speed search is carried out as it PI controls the ripple
current which is generated by the counter electromotive
force during no-load rotation. The counter electromotive
force is proportional to the idle speed. This mode
establishes the direction of the idling motor
(forward/reverse) and the speed search function is stable
regardless of the direction of the idling motor and direction
of the start command. However, because the ripple
current is used, the frequency is not determined
accurately at low speeds (about 10-15 Hz). Re-
acceleration may start from zero speed.
Type and Functions of Speed Search Setting
Speed search for general
acceleration
Initialization after a fault
Restart after instantaneous power
interruption
LCD bit representation in parameter view. When the top segment is black, bit is
set to "ON".
Speed search can be selected to operate among the following 4 conditions.
Speed search for general acceleration: If bit 0 is set to 1 (enabled), speed
search is enabled for normal accelerating starts with rotating motor/load. The
speed search function prevents faults when starting the inverter with rotating
motor/load.
Initialization after a fault: If Bit 1 is set to 1 (enabled) and PRT-08 (RST
Restart) is set to 1 (Yes), after a fault reset, speed search accelerates the
motor to the operating frequency used before the fault.
Automatic restart after reset of a fault: If bit 2 is set to 1, and if a low voltage
trip occurs due to a power interruption but the power is restored before the
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