I651
GB
03
22
31100488
5
5.2 MANAGEMENT OF STARTING RAMPS WITH CURRENT LIMIT (ONLY FOR ADXNP)
The advanced version ADXNP integrates current transformers, which allow to limit the current during the starting phase below a programmable threshold (P01.07) and to adapt the acceleration ramp according to the
load conditions.
If the current delivered by the highest of the three phases reaches or exceeds the set limit, the ADXNP reduces the voltage applied to motor to remain below the maximum limit setting (P01.07). This behavior has
priority over the voltage ramp, and thus momentarily flattens it. Obviously, reducing the current also reduces the motor's torque delivery: if the current limit is set too low, the torque delivery may be insufficient to
overcome the resistant load and start the machine. It’s about finding the right compromise when setting this parameter. If this situation occurs, it will trip the protection for starting time too long or the motor thermal
overload protection.
6. FUNCTIONAL DIAGRAM
Here below it is represented the functional diagram of the soft starters ADXN.
Note. The current limit also depends on the starting voltage set and the load conditions at the start-up. For example, by setting a very low current limit (e.g. under the 300%) and an high starting voltage, the inrush
current might increase above the limit set on the parameter P01.07 (due to the fact that the ramp starts from a high voltage value and at the same time the load requires an high torque), condition necessary to
overcome the resistant torque of the load, allowing the motor to start and preventing it from stalling.
Auxiliary power supply
(A1-A2)
Line voltage
(L1-L2-L3)
Start
(ST-A1)
Motor voltage
(T1-T2-T3)
TOR output
(default: 11-24)
POWER LED
RUN LED
LIN.CONT output
(default: 11-14)
Voltage ramp starting
without reaching the current limit
Voltage ramp starting,
with current limit trip
G
B