In general, instantaneous values are calculated in EMT simulations. Such instantaneous values must be processed in order to calculate RMS signals, such as voltages and current.

The following are two approaches available in PowerFactory for this purpose:

1. Measurement devices:
   • The RMS voltages and currents are recorded by StaVmea and StaImea elements, respectively;
   • The measurement devices are stored in the cubicle at the location from which the signals are gathered.
2. Relay model:
   • The RMS voltages and currents are recorded by the measurement block of a relay model
   • The relay model is linked to a VT / CT
   • Note that the use of the relay model / measurement block requires a Protection license

The following attached projects show the calculation of the RMS voltages and currents following the two approaches:

• "RMS values in EMT simulation (Meas)": the RMS values are calculated using measurement devices.
• "RMS values in EMT simulation (Relay)": the RMS values are calculated using a relay model.

Note that a Power Measurement Device (StaPqmea) can be used to calculate the RMS the power flow at a cubicle of any element, which is connected to a terminal/busbar. The measured active and reactive power can then be fed for example into a DSL model of a controller.