CEE Relays Ltd.

87C Whitby Road, Slough, SL1 3DR

Telephone: (01753) 576477        Fax: (01753) 825661

Website: www.ceerelays.co.uk

Modelling Capacitance

Each PTW study module models capacitance in a different way. For a full discussion of how capacitance is taken into account, please refer to the manuals (available in electronic format on the installation CD-ROM).

Capacitance can be entered into different components in different ways. The choice of which method to use depends on what information you have:

• Enter directly into a PI-equivalent network component.
• Enter into a PI-equivalent network component using the Single-Core Pipe Type library model.
• Enter directly into a cable component.
• Enter into a cable component using data from the PTW cable library.
• Use PTW's transmission line model.
• Use a capacitor component attached to the busbar at either end of the cable.

Using PTW's cable models makes sizing cables much easier, whereas the transmission line and single-core pipe type library models are more convenient if accurate cable capacitance is not known. Using a capacitor component is useful with older versions of PTW, where capacitance was not included in the standard cable model.

When entering series reactance into a pi-equivalent network, positive values should be entered for inductance, and negative values should be entered for capacitance.