# RL section

This section describes RL section

RL section properties can be defined in two ways, depending on the chosen model definition parameter. If the R-L model definition is selected, the user defines the cable length and the per length resistance and inductance. Properties window of RL section with R-L model definition chosen is shown in Figure 1. If the S-U model definition is chosen, the user has to define maximal complex power that is expected through the line, voltage and frequency. The section resistance and inductance are then approximated by assuming a 10 % voltage drop over the section impedance. The properties window in this case is show in Figure 2.

Properties input can be in metric or imperial unit systems. The preferred one can be chosen in combo box Unit system. By default it is set to imperial. RL section component supports 1-5 phases. This number can be changed in the Number of phases property.

Symbol in Typhoon schematic editor and schematic diagram of the single phase RL section is shown in Figure 3 and Figure 4.

## Coupling

If Number of phases is 2,3 or 4, TLM coupling can be inserted. If Embedded TLM coupling is enabled, inductance will be divided between TLM and inductors (inductors will be hidden in the TLM). TLM to embedded inductors ratio can be determined by compiler, but also it can be specified explicitly. If Automatic option is selected, ratio will be determined by discretization method. If Manual option is selected, ratio can be explicitly set to meet user requirements. For more information on TLM couplings please refer to Core couplings - TLM.