MEPworx Wiring – Transformer Overload Ratings

By David Wren

It is not uncommon for transformers to be designed to run at substantial overloads. Typically, a range of +10-20% is common at peak times. Wiring's calculation and design check routines now have the facility to take into account increased, or temporary, overloads.

For most transformers, the absolute maximum overload before an error is reported is typically 140% of the design rating e.g. for a 350kVA transformer, a maximum temporary overload of 140% would equate to a load of 490kVA. Or a 120% overload, would be 420kVA.

You now have the facility to be able to explore the operational conditions of the transformer and sub-mains distribution, under various temporary overload conditions.

To set a desired overload factor, on the MEPworx front screen, go to the Utilities tab and select Defaults.

In the Defaults Editor, select Wiring from the pull-down Program list.

Simply scroll down to the new entry for, ‘Temp Tx_Oload’ and enter the required maximum overload value as a % factor of the design rating.

In the above example, the ‘Temp Tx_Oload’ has been set to 1.2 = 120%.

After the desired value has been entered, please remember to Save any changes before closing the Defaults Editor.

When you are back in the Wiring program, if the calculated overload is now too great for the transformer, the main supply Cable will show an error message. e.g.

Please also refer to the context appropriate in-program Help (F1) for more information.