CHAPTER 7 - APPLICATIONS AND PROGRAMMING
126
7.1.4
Starting by Current Ramp
(P202=4)
1) To start the motor with current ramp you must apply load on the
motor. No-load tests can be done by voltage ramp;
2) Use this function to help starting loads that require a lower initial
torque, as fans and blowers;
3) When such a load is started with fixed current limit, you can note
that the motor starts the load and then it speeds up;
4) As solution we recommend setting a lower initial current to only run
the load and the increase the current limit gradually until the end of
the start. In this way you will certainly ensure a smooth start;
5) Set P111 to the current value required to put the motor in movement
only;
6) Set P112 initially to 75% of P102(20s) = 15s and then increase it
gradually;
7) The motor must run as soon as it is enabled;
8) Set P110 with current limit that maintains the motor accelerating;
9) The motor must accelerate till the start end.
Figure 7.6
– Starting with current ramp and initial lower current
NOTES!
1) If the current limit is not reached during the starting, the motor will
start immediately.
2) P401 must be according to current of the used motor;
3) Current Limits that are too high result in torques that are too low for
the motor start.
Always maintain the motor running after it has been enabled;
4) If errors are detected during the motor start, check all connections
of the Soft-Starter to the power line, the motor connections, the
voltage levels of the power line, the fuses, circuit-breakers and
disconnecting switches.
I(A)
Start
I Nominal
P110
P102
0
Enable
Current Ramp
Disable
t(s)
I Limit
Maximum Time
P111
P112
P110
P102
Current
Ramp
P401
P400
P112
P111
P640
P406
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