19 • STARTING PROCEDURE
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8.2
Examples of starting curves
Light loads - pumps, etc.
Current limit - set to 300%
Initial Voltage - set to 30%
Ramp-up time - set to 5 sec.
U%
100%
5
t
I%
600%
100%
50%
30%
10%
400%
300%
t
Upon start, the voltage quickly increases to the Initial Voltage value (30% Un) and then gradually ramps-up to
nominal.
The current will simultaneously increase to peak current value, which can be the Current Limit setting or less,
before smoothly decreasing to the operating current. The motor will accelerate to full speed quickly and
smoothly.
High inertia loads – crushers, centrifuges, mixers etc.
Current Limit - set to 350%
Initial Voltage - set to 50%
Ramp-Up time - set to 5 sec.
U%
100%
20
t
I%
600%
100%
50%
10%
350%
t
20
End of process
Motor acceleration time
to full speed is as
required?
No
Yes
Apply Start command
If acceleration time is too short, increase
“Acceleration Time” setting and/or decrease C.L.
(when decreasing CL, make sure motor increases
speed gradually and does not stall).
A
