7.6
Current limit
Current limit sets a maximum value of the starting current
output to the motor. The time it takes to reach full voltage
can be longer than the set Start ramp Time when Current
limit is enabled.
There are three different Current limit functions:
•
Normal current limit
•
Dual current limit
•
Ramp current limit
WARNING
If the load is very heavy, current limit can
prevent the current to decrease below the
set current level and cause overheating.
Normal current limit
When using Normal current limit and the set current
limit
is reached, the output voltage stays stable until the
current level falls below the set current limit. Then the
start ramp continues.
Dual current limit
Dual current level has two settable current limit levels.
When the first current limit is reached, the current limit
will keep the output voltage constant untill the configured
time has passed or the current decreases. If the current
decreases, the softstarter continues the voltage ramp. If
the second configured Current limit time, has passed and
the current has not decreased, the softstarter increases
the current to the second level, and then it continues the
voltage ramp.
See Figure 82.
If the current reaches the second current limit, the
softstarter will behave as for the normal current limit.
Dual current limit can be used as a back-up function to
prevent overheating.
Ramp current limit
When the current reaches the first current limit level the
output voltage restricts the current from increasing at a
maximum linearly curve up to the second current limit.
The configured time determines the time it takes for the
current limit to reach the second current level.
When the current reaches the second current limit, the
softstarter will behave as for the normal current limit.
Ramp current limit can be used as a back-up function to
prevent overheating.
Current limit
is configured with the following
parameters:
Parameter
Description
Setting range
Default value
03.01
Current limit type
Set the Current limit type.
Off, Normal,
Dual, Ramp
Normal
03.02
Current limit level
Sets the first level to which the current is limited during start.
1.5 ... 7.5 xIe
4.0 xIe
03.03
2nd curr lim level
Sets the level of the second current limit.
1.5 ... 7.5 xIe
7.0 xIe
03.04
2nd curr lim time
Sets the time limit from the starting signal when the second
current limitation will be activated.
2 ... 120 s
8 s
Figure 82: Dual current limit.
82
1SFC132081M0201
U
30%
100%
I
Time
Current limit
2nd current limit time
Dual current limit
Time
7
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]
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