SMA SC 500CP XT - Manual (Page 96)

10.3.2.4 Active Power Limitation as a Percentage of Nominal Power: WCnstNom Mode
The active power limitation is set as a percentage value via the parameter P‑WNom. The percentage value refers to
the parameter Pmax. The parameter P‑WNom indicates what percentage of the maximum possible power is to be
fed in. The parameter P-WNom can be changed during feed-in operation.
10.3.2.5 Active Power Limitation via Standard Signal: WCnstNomAnIn Mode
The active power limitation is set via an analog signal at the input terminals for the setpoint. This is usually implemented
by a ripple control signal. The electrical current strength of the connected signal determines the nominal active power.
The analog measured values must be between 4 mA and 19 mA. If the analog signal is less than 2 mA, an error
message will be displayed in the instantaneous value P-WModFailStt.
Signal Power limit Description
< 2 mA Last valid value or Pmax after restart Signal is in the invalid range.
2 mA to 4 mA 0 kW No power is fed into the grid.
4 mA to 19 mA 0 kW to Pmax The energy fed into the grid is determined by a character-
istic curve.
> 19 mA Pmax The energy fed into the grid equals Pmax.
The analog value is converted to a setpoint for power limitation. Here, the parameter Pmax forms the end point of the
linear characteristic curve.
10.3.3 Reactive Power Control
10.3.3.1 No Reactive Power Control: Off Mode
The reactive power setpoint is limited to 0 kVAr. This setpoint cannot be controlled.
10.3.3.2 Reactive Power Control with Setpoint Command via Modbus Protocol:
VArCtlCom Mode
The reactive power setpoint is received by the communication unit and transmitted to the inverter. The setpoint is
transmitted as a percentage value and converted to kVAr in the device. If the inverter has not received any signal for
five minutes, the error message Q-VArModFailStt will be displayed.
10.3.3.3 Reactive Power Control with Setpoint Command via Modbus Protocol:
PFCtlCom Mode
The reactive power setpoint is received by the communication unit and transmitted to the inverter. The setpoint is
transmitted as a displacement power factor cos φ. If the inverter has not received any signal for the last five minutes, an
error message will be displayed in the instantaneous value Q-VArModFailStt.
10.3.3.4 Reactive Power Control with Absolute Value: VArCnst Mode
The reactive power setpoint is set via the parameter Q-VAr. The parameter Q-VAr is permitted to be within the range
from ‒Qmax to +Qmax.
10.3.3.5 Reactive Power Control as a Percentage of the Nominal Power: VArCnstNom
Mode
The parameter Q-VArNom is used to set the reactive power setpoint in %. The parameter Q-VArNom refers to
Pmax. If the calculated amount of reactive power exceeds the predefined value of Qmax, the power will be limited
to Qmax. If the calculated amount of reactive power falls below the predefined value of ‒Qmax, the power will be
limited to ‒Qmax.
10 Function Description SMA Solar Technology AG
User Manual SCCPXT-BA-E4-en-54 96