Upper section of this tab contains settings about the supply voltage, earthing system, frequency and voltage drop limits.

Voltage may have one or two text fields depending if it is a single phase or three phase source. The one on the left hand side defines the voltage between the phase and neutral terminals and this is the only option if the source is a single phase one, and the one on the right hand side defines the voltage between two phase terminals in case of a three phase source. As the user modifies one of these field ElectrcialOM will calculate the other automatically.

Earthing system has two drop down list. The first one has 3 options as TN, TT, and IT. If the TN system is selected, then the second drop down list will appear with 2 options as TN-C-S and TN-S.

Supply frequency has 2 options as 50Hz and 60Hz.



Maximum values of voltage drop from the origin of the installation section has three options to select. This options will define the allowed voltage drop limit (in percent) for specific circuits, and also will allow an extra headroom for circuits longer than 100 metres.



Public supply options will set lighting circuits to 3% and other circuits to 5% maximum allowed voltage drop from the origin.

Private supply options will set lighting circuits to 3% and other circuits to 5% maximum allowed voltage drop from the origin.

Other (user defined limit) enables the user to set a manual value for the voltage drop limit, however, it will be applied to all types of circuits.


Middle section is reserved for source type and characteristics settings, and a tick box to define cables from the source to the origin of the system, if any. Depending on the selected source type, Method of Supply, Source characteristics may be visible or not. First 3 options are for Cyprus market and not advisable to be used for projects located in a country other than Cyprus.

  • Low voltage (400V/230V) from a sub-station with maximum transformer rating 1000kVA: If this option is selected, ElectrcialOM will display Supply cable and Cable length drop down lists and the voltage fields will be greyed out. This option is intended for Cyprus market and the source characteristic data is taken from EAC (AHK).



  • Low voltage (400V/230V) parallel operation of two transformers with rating 1000kVA and Low voltage (400V/230V) supply of an exclusive customer using a transformer with rating 1600kVA options do not have a Source characteristic data and the voltage fields are greyed out. These options are intended for Cyprus market and the source characteristic data is taken from EAC (AHK).
  • User defined source: If this option is selected, ElectricalOM will display Source characteristics data, where the user can modify the power and the percent impedance of the transformer. These data will be used to calculate the fault currents and power factor. Next to these ElectricalOM will display the Load capacity of the source calculated according to the entered values in Amperes.
    • Calculate fault and Calculate power factor buttons: 



  • Transformer: This option will also display the primary side voltage and fault impedance of the transformer. Next to these ElectricalOM will display the Load capacity of the source calculated according to the entered values in Amperes.



If this option is selected, ElectricalOM will display an additional tab, High Voltage Settings, at the end of the tabs area. Please see HV and Arc Flash Settings for more details.