How can a motor damage curve be fully implemented in Time-Overcurrent plot?

Category:
Protection
Answer

There are two possible ways:

1) Right click on the asynchronous machine of interest using the right mouse button and choose->Show->Time-overcurrent plot.

A new time overcurrent plot will automatically be created showing the direct on-line (DOL) starting characteristic of the motor.

2) If detailed thermal damage curves such as those shown in the attached datasheet are required, the alternative approach described below can be used:

- Right-click on the existing Time-Overcurrent plot and choose ->Add...->Motor Starting Curve

- In the newly opened window, select Asynchronous Motor as the motor type.

- Enter the rated parameters on the Motor Data page

- Select the Detailed Representation option and assign a corresponding damage curve (TypChatoc) object.

The challenge here is to digitise the damage curve in the datasheet so that it can be used by PowerFactory. If general if you have a graphical representation of a two dimensional characteristic stored in a PDF; PNG or any other format you can easily digitise it in PowerFactory.

The FAQ: How can a Fuse be modelled using manufacturer's characteristics??  describes the digitisation process.

In the attachment, you can find a .png file containing an extract from a datasheet showing a motor damage characteristic and a PowerFactory project file illustrating the two curves described above.

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