B&R ACOPOSinverter P84, User Manual

Page: 162 / 405

Programming guidelines
162 ACOPOSinverter P84 User's Manual 2.10
Code Name/Description Factory settings
nrd [Noise reduction] Depending on the size
nO [No] (nO) : Fixed frequency.
YES [Yes] (YES) : Frequency with random controlled modulation. Factory setting up to the sizes 8I84T204500.01P-1 and 8I84T407500.01P-1.
Random frequency modulation prevents any resonance, which may occur at a fixed frequency.
SUL
[Motor surge limit.] [No]
(nO)
This function limits motor overvoltages. It is used under the following circumstances:
•
Motors to NEMA specification
•
Japanese motors
•
Spindle motors
•
Rewound motors
nO [No] (nO) : Function not active.
YES [Yes] (YES) : Function active
This parameter is forced to [No] (nO) if [sine-wave filter] (OFI) , previous page = [Yes] (YES) .
This parameter can remain [Nein] (nO) for 230/400 V motors used with 230 V or if the cable length between the inverter and motor does not
exceed the following lengths:
• 4 m with unshielded cables
• 10 m with shielded cables
SOP [Volt surge limit. opt] 10 μs
Optimization parameter for transient overvoltages at the motor terminals. This parameter can be accessed if [Motor surge limit] (SUL) = [Yes]
(YES) .
Set to 6, 8 or 10 μs according to the following table.
The value of parameter "SOP" corresponds to the damping time of the cable used. It is defined to prevent the
superimposition of voltage wave reflections resulting from long cable lengths. It limits overvoltages to twice the
DC bus rated voltage.
The following table shows examples of the relationship between parameter "SOP" and the length of the cable
between the inverter and the motor. For longer cable lengths, a sine-wave filter or a dV/dt protective filter must
be used.
• For motors in parallel, the sum of all the cable lengths must be taken into consideration. Compare the length
given in the table row corresponding to the power for one motor with that corresponding to the total power,
and select the shorter length. Example: Two motors with 7.5 kW (10 HP): Take the lengths from the 15 kW
(20 HP) column that are shorter than those in the 7.5 kW (10 HP) column, and divide the corresponding
length by the number of motors to obtain the length per motor (with unshielded "GORSE" cable and SOP
= 6, the result is 40/2 motors = 20 m per motor maximum for each 7.5 kW (10 HP) motor).
In special cases (for example, different types of cable, different motor powers in parallel, different cable lengths
in parallel, etc.), we recommend using an oscilloscope to check the overvoltage values obtained at the motor
terminals.
To retain the overall inverter performance, the SOP value is not permitted to be increased unnecessarily.