55
• Starting Procedure
Continued from previous page
6.2
Examples of Starting Curves
6.2.1
Light Loads - Pumps, Etc.
(In these cases the actual current is always lower than the
Current Limit
setting)
Starting Voltage-
set to 30%
Current Limit
-
set to 300-350%
Ramp UP Time
-
set to 10 sec.
Upon start, the voltage quickly increases to the
Starting Voltage
value (30% of Un) and then gradually ramps-
up to nominal.
The current will simultaneously increase to peak current value (lower than the
Current Limit
setting), before
smoothly decreasing to the operating current.
6.2.2
High Inertia Loads: Crushers, Centrifuges, Mixers, Etc.
(In these cases the actual current is at the
CURRENT LIMIT
setting during part of the starting time)
Starting Voltage–
set 40%
Current Limit–
set 400%
Ramp UP Time
–
set 3 sec
•
Check
Last Start Time
and set
Max. Start time
to approximately 5 seconds
longer than the
Last Start Time
.
•
For future reference it is advised to keep records of the following parameters in the
Statistical Data:
Last Start Time:
Last Start Curr.:
Motor acceleration
time to full speed is
as required?
No
Yes
If acceleration time is too short, increase
Ramp
UP Time
setting and/or decrease
Current
Limit
setting (when decreasing
Current
Limit
, make sure that the motor increases
speed gradually and does not stall).
A
Apply the START command
