Menu 21
Commander SK Advanced User Guide
195
Issue Number: 9 www.controltechniques.com
When this parameter is set to On(1), it signifies that motor map 2 is active.
This parameter can be programmed to a digital output to give a signal to an external circuit to close a second motor contactor when motor map 2
becomes active.
Pr
21.16
works in conjunction with Pr
4.16
and Pr
4.25
. The motor protection modes set-up by Pr
4.16
and Pr
4.25
for motor 1 will be used for motor
2 but the thermal time constant for motor 2 will be defined in Pr
21.16
.
See Pr
on page 71 for further details.
This parameter defines the current limit as a percentage of the rated active current. When the motor rated current is set lower than the drive rated
current, the maximum value of this parameter increases to allow larger overloads.
Therefore, by setting the motor rated current to a lower value than the drive rated current, it is possible to have a current limit greater than 165%. An
absolute maximum current limit of 999.9% is applied.
In frequency control mode (Pr
4.11
= OFF), the drive output frequency is modified if necessary to keep the active current within the current limits as
shown in the following diagram:
The active current limit is compared with the active current and if the current exceeds the limit the error value passes through the PI controller to give
a frequency component which is used to modify the ramp output. The direction of the modification is always to reduce the frequency to zero if the
active current is motoring, or to increase the frequency towards the maximum if the current is regenerating. Even when the current limit is active the
ramp still operates, therefore the proportional and integral gains (Pr
4.13
and Pr
4.14
) must be high enough to counter the effects of the ramp. For
method of setting the gains see Pr
In torque control mode the current demand is limited by the active current limit. For operation of this mode see Pr
21.15
Motor 2 active
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
1
Range
OFF(0) or On(1)
Default
OFF(0)
Update rate
Background
21.16
Motor 2 thermal time constant
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
Range
0 to 250 s
Default
89
First motor
parameter
Pr
Update rate
Background
21.17 to 21.28
Unused parameters
21.29
Motor 2 symmetrical current limit
Coding
Bit
SP
FI
DE Txt VM DP ND RA NC NV
PT
US RW BU PS
1
1
1
1
1
1
Range
0 to MOTOR2_CURRENT_LIMIT_MAX %
Default
165.0
First motor
parameter
Pr
Update rate
Background
P Pr
4.13
I Pr
4.14
Current limit
active
1
0
Active
current
limit
Post ramp
reference
Ramp
Active
current
-
+
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