ABB ACS880 Series, Руководство по прошивке

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Description Control
scenario
Parameter 74.30 is set ON, so that when restart delay time is elapsed, the speed
measurement function starts automatically.
6
The time needed for the Backspin speed observer function to detect the actual
motor speed is defined with parameter
74.39 .
2-3, 7-8,
13-14
When Backspin speed observer is active, the drive start command has no effect
until measured speed gets in to the safe-to-restart speed region defined with
parameters
74.31 and 74.32 .
7-9
The speed observer function triggers the speed check timer set in parameter
74.33 when the measured speed is within the safe-to-restart speed region.
9-11
If the measured speed is outside safe-to-restart speed region, the speed check
timer will reset. 10
If the measured speed is within the safe-to-restart speed region defined in
parameter
74.33 , then the speed observer function routine is over. The drive
stops modulating and parameter 74.99 , bit 8 is set to TRUE.
11-12
In case user drive start command is active, then immediately after speed check
time is elapsed the flying start sequence is initiated and drive takes control over
the pump-motor to go over the starting routines and then accelerate it to the
production speed.
The drive is waiting for the user to initiate the drive start command. 12-13
As soon as you give the drive start command, the drive repeats speed measure-
ment routine to ensure that the actual speed is within the safe-to-restart speed
region. The drive then proceeds with normal starting routine without any speed
check time delay. 13-14
If the speed is outside the safe-to-restart speed region, then all the speed super-
vision procedure is repeated from point 8.
The drive gets in to normal production state through the starting routines. 14-15
￭ Backspin speed observer constraints
Backspin speed measurement is a special drive control mode that requires physical
cable connection to the motor. Therefore, the motor contactor should be closed
all the time for the function to work. If the contact to the motor gets impaired
while monitoring, then manually restart after the connection is restored.
Backspin speed measurement sensitivity has its limitations at slow speeds. The
lowest detectable speed varies (not the same) depends on motor size and can be
as low as 1Hz with 900kW motor. With small motors (1-10kW), the speed detection
routine cannot produce accurate measurement below 4Hz. The general guideline
for the function set up to test speed measurement capacity with each type of
motor in use to assess the lowest feasible speed measurement.
Backspin speed measurement cannot always reliably detect zero-speed crossing
from positive to negative speed and vice versa. The general guideline is to always
have the Restart delay function enabled and active for several minutes after process
is interrupted. It delays the Backspin Speed Observer function to engage, thus
48 ESP program features