Siemens sinamics dcp Operating Instructions Manual page 233

The specified setpoint is always converted to a reactor current setpoint, which is used for
control.
The reactor current is the current measured by the current actual value acquisition in the
SINAMICS DCP.
This current is always the current that flows on the side with the lower voltage.
Correction current controller
See function diagram 6806 in the SINAMICS DCP List Manual.
The correction current controller is used to improve the accuracy of the current control, by
feeding in an externally measured current actual value.
A BICO input (p55156) is provided, which allows an externally derived input current actual
value or output current actual value to be used in the calculation internally. (The external
current transformer should have a precision greater than +/-0.5 %.)
If the external current actual value is used, it is continuously compared with the internal
current actual value. If a deviation of more than +/- 2 % is detected by the device rated
current, fault message F60511 is output. The DCP continues to be protected from overload
by the current actual value acquisition.
The external current actual value can be fed in via existing analog inputs of the CUD.
Moreover, the external current actual value can be fed in digitally via the field bus.
Dynamic overload capability
See function diagrams 6808 and 6810 in the List Manual of the SINAMICS°DCP.
SINAMICS DCP permits operation with overload profiles. Operation can be performed for a
short time with currents of up to 160 % of its rated current.
The maximum overload duration depends both on the development over time of the overload
current and supply air temperature as well as on the load history of the device, and may
differ depending on the device.
Each overload must be preceded by an underload. Once the maximum permissible overload
duration has elapsed, the current setpoint must be reduced to at least the base-load current.
Three overload profiles per parameter can be selected:
p55080 = 0
Note:
Not all load profiles can be set on every device. For example, on the 30 kW device, only
settings 0 and 1 are permitted. F60058 is output if a non-permitted profile is set.
If load profile "increased current" is set in a low ambient temperature, an increased current is
permitted long term (see p55081). However, temperature-dependent derating will start at a
lower ambient temperature than in operation with increased current.
The following figures show the overload profiles "low overload" and "high overload."
All stated currents always refer to the current on the side with the lower voltage.
SINAMICS DCP
Operating Instructions, 05/2016, A5E34382853K
Load profile "no overload" (i.e. the overload capability is deactivated)
= 1 Load profile "increased current"
= 2 Load profile "low overload"
= 3 Load profile "high overload"
Operation
8.9 Closed-loop control
233