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In a common DC bus system, only the Master drive should have the power loss logic enabled. Otherwise each
drive will be following its own ramp and web speed will no longer be maintained.
With the DC link connected together, once the master starts to regenerate and the slaves will follow and the link
voltage will be maintained by the sum of all the drives.
The slaves must follow the master as quickly as possible to reduce the drain on the link, the 5703 setpoint
repeater is a good way of achieving this.
Some DC braking should be provided to prevent over-voltage trips.
00,
f.........PWR LOSS CNTRL
f...........ENABLE [639] = FALSE
f...........TRIP THRESHOLD [640] = 0 VOLTS
f...........CONTROL BAND [657] = 20 VOLTS
f...........DECEL RATE [641] = 2.50 %
f...........ACCEL RATE [644] = 0.50 %
f...........TIME LIMIT [643] = 30.000 SECS
f...........PWR LOSS ACTIVE [766] = FALSE
ENABLE
Enables the power loss control option, without this TAG set the power loss
software is inactive.
TRIP THRESHOLD
The TRIP THRESHOLD sets the DC Link level in volts at which the
power loss operation is triggered.
CONTROL BAND
The CONTROL BAND sets the level above the TRIP THRESHOLD at
which the power loss operation is paused.
If the DC link level remains above this level for 500 cycles (About 500ms)
the power loss recovery sequence is begun and the setpoint ramps back up
to the demanded setpoint.
DECEL RATE
The DECEL RATE sets the rate at which the drive decelerates the load to
keep the DC-Link pumped up. This should be set at the drives’ worst
operating point, highest load / lowest inertia.
ACCEL RATE
The ACCEL RATE sets the rate at which the drive accelerates back up to
the actual setpoint. This should be set to about a 1/10th of the DECEL
RATE..
TIME LIMIT
The TIME LIMIT sets the maximum amount of time that the drives is
allowed to be in the power loss mode. Once this time expires the drive will
trip on POWER LOSS TRIP alarm.
PWR LOSS ACTIVE
The PWR LOSS ACTIVE is a diagnostic that indicates that the power loss
is active.
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The Speed setpoint can come from one of two sources (Local or Remote). In Local mode the setpoint is
derived directly from the Op-Station value and the reset of the drives block diagram is running but not used in
the calculation of the setpoint.
The Speed Demand has a 10% over-range, although input 0 only has the range
±
105.00%. This allows take up
slack to operate over the whole speed range.
DIRECT SPT1
This setpoint processing is synchronous with the speed loop (every 1.1 ms)
and can be used by an external trim loop (positioning systems etc.). When
not in use this should be disabled.
This manual was downloaded on www.sdsdrives.com
+44 (0)117 938 1800 - info@sdsdrives.com