CHAPTER 7 - APPLICATIONS AND PROGRAMMING
125
7.1.3
Starting by Current Ramp
(P202=4)
1) For starting 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 an higher initial
torque , as compressors and belt conveyors;
3) When such a load is started with fixed current limit, you can note
that the motor requires some time to start the load and then it
speeds up quickly;
4) As solution we recommend to set an initial current limit to overcome
the load start and then programming a current limit that enables the
load acceleration till the start end. In this way you certainly will
ensure a smooth start;
5) Set P111 to the current value required to start the motor;
6) Set P112 initially to 2s, i. and., to 10% of P102(20s) = 2s 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.
Figure 7.5
– Starting with current ramp and initial higher current
NOTES!
1) If the current limit is not reached during the starting, the will motor
starts immediately.
2) P401 setting must be according to current of the used motor;
3) Alow Current Limit results in too low torque for the motor start.
Always maintain the motor always 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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