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Unidrive SP Regen Installation Guide
99
Issue Number: 2 www.controltechniques.com
If the load change, drive voltage rating, motor voltage or DC Bus set-point are different then
∆
V is calculated from:
∆
V = 80V x K
L
X K
RAT
x K
MV
X K
SP
Where:
K
L
= load change / 200%
K
RAT
= Drive voltage rating / 400
K
MV
= motor voltage / 400
K
SP
= 700 / DC Bus voltage set point
In some applications, particularly with a high d.c. bus voltage set point and low switching frequency it may be necessary to limit the rate of change of
power flow to prevent over voltage trips. A first order filter on the torque reference of the motor drive (i.e. using Pr
4.12
) is the most effective method
to reduce the transient further. (A fixed limit of the rate of change of torque demand is less effective.) The following table gives an approximate
indication of the reduction in
∆
V for different time constants. (As already mentioned the value of
∆
V given if for an instantaneous change of torque
representing the worst case. In applications where a speed controller is used in the motor drive the transient will already include an inherent filter).
The transient produced is approximately proportional to the voltage controller gain. The default voltage controller gain is set to give a value that is
suitable for most applications. The gain may need to be increased if the DC Bus capacitance is high compared to two drives of similar rating coupled
together. However, care must be taken to ensure that the gain is not too high as this can cause excessive ripple in the DC Bus voltage.
When the Regen drive has powered-up through the soft-start and the DC Bus voltage has stopped rising and is higher than the contactor close
voltage this bit changes from 0 to 1. If the DC Bus voltage falls below the contactor open voltage DC or the system is synchronised and the AC
voltage falls below contactor open voltage AC this bit changes to zero. When regen mode is selected this bit is routed to the drive relay output
(Terminals 41/42) as default.
This output, or an alternative output, can be used to control the soft-start contactor.
When regen mode is selected Pr
3.08
is the destination for the digital input on terminal 25 (T25) as default. This input, or an alternative input, should
be connected to an auxiliary contact on the soft-start contactor so that it follows the state of the contactor. The Regen drive will only attempt to
synchronise to the supply when this parameter is one. This parameter is also used to monitor the contactor when the Regen drive is running. If at any
time this parameter is zero the Regen drive is immediately disabled.
When the unit has been enabled and successfully synchronised this bit will become active. If the Regen drive attempts to re-synchronise or trips, this
bit becomes inactive. When regen mode is selected this bit is routed to a the digital output on terminal 24 (T24) as default. The output, or an
alternative output, should be used to enable the motor drive(s) connected to the DC bus of the Regen drive.
Time constant
Change in
∆
V
20mS
x 0.75
40mS
x 0.5
3.07
Close start up contactor
Drive mode
Regen
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
Update rate
4ms
Drive Rating
Vac
Contactor Close
Vdc
Contactor Open
Vdc
Contactor Open
Vac
200V
215
205
75
400V
430
410
150
575V
565
540
225
690V
565
540
225
3.08
Main contactor closed
Drive mode
Regen
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
Default
Regen
0
Update rate
4ms
3.09
Enable motor drive
Drive mode
Regen
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
Update rate
4ms
Summary of Contents for SP1201
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