Introduction
Parameter
x.00
Parameter
description format
Keypad and
display
Serial
communications
CT Modbus
RTU
PLC Ladder
programming
CTSoft Menu 0
Advanced parameter
descriptions
Menu 6
Commander SK Advanced User Guide 91
Issue Number: 9 www.controltechniques.com
When the drive is enabled with this bit at 0, the output frequency starts at zero and ramps to the required reference. When the drive is enabled and
this parameter has a non-zero value, the drive performs a start-up test to determine the motor speed and then sets the initial output frequency to the
synchronous frequency of the motor. The test is not carried out, and the motor frequency starts at zero, if the run command is given when the drive is
in a stopping state, or when the drive is first enabled after power up with UR I voltage mode, or when the run command is given in UR S voltage mode.
For the test to operate correctly it is important that the stator resistance (Pr 5.17, Pr 21.12) is set up correctly. This applies even if fixed boost (Fd) or
square law (SrE) voltage mode is being used. The test uses the rated magnetising current of the motor during the test, therefore the rated current
(Pr 5.07, Pr 21.07 and Pr 5.10, Pr 21.10) and power factor should be set to values close to those of the motor, although these parameters are not as
critical as the stator resistance.
Stationary lightly loaded motors with low inertia may move slightly during the test. The direction of the movement is undefined. Restrictions may be
placed on the direction of this movement and on the frequencies detected by the drive as in the above table.
0: OFF Low DC bus operation disabled
1: On Low DC bus operation enabled
The Low DC bus operation is designed to enable 3 phase 400VAC (medium voltage) Commander SKs to be run off a single phase 200VAC (low
voltage) supply in the event of a primary 400VAC supply failure.
When the primary supply fails, the back up supply can be switched in. This will allow the drive to control the motor at a reduced power, for example to
move an elevator up or down to the next floor.
There is no de-rating as such when low DC bus operation is enabled however the power will be limited by the reduced voltage and ripple generated
on the DC bus of the drive.
When Pr 6.10 is enabled and the DC bus voltage is less than 330VDC, the drives display will flash Lo.AC (Low AC) to indicate that it is supplied from
a low voltage back up supply.
This mode is designed for use with a backup power supply and not for using a 400VAC (medium voltage) Commander SK in a 200VAC (low voltage)
application. As shown in the following diagram, the drives power down save parameters are saved at point 2. If the drive was to be used on a 200VAC
supply, the DC bus will never fall through point 2 and power down save parameters will not be saved.
Not available on Commander SK size 2 to 6.
Low DC bus operation voltage levels (Pr 6.10 enabled)
>425VDC - normal operation
<330VDC - LoAC operation
<230VDC - UV trip
See Figure 10-16 Low DC bus operation on page 92.
Only available on SKB, SKC and SKD.
6.08 Unused parameter
6.09 Catch a spinning motor select {33}
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
111
Range 0 to 3
Default 0
Update rate Background
Pr 6.09 Function
0 Disabled
1 Detect positive and negative frequencies
2 Detect positive frequencies only
3 Detect negative frequencies only
6.10 Low DC bus operation
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
111
Range OFF(0) or On(1)
Default OFF(0)
Update rate Background
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