Differences Between The North American And European Standards; Programmable Curves; Principles Of Implementation; Figure 32: Ieee Very And Extremely Inverse Curves - GE MiCOM P40 Agile Technical Manual

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P14x
IEEE Very Inverse Curve
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Figure 32: IEEE very and extremely inverse curves

2.1.5

DIFFERENCES BETWEEN THE NORTH AMERICAN AND EUROPEAN STANDARDS

The IEEE and US curves are set differently to the IEC/UK curves, with regard to the time setting. A time multiplier
setting (TMS) is used to adjust the operating time of the IEC curves, whereas a time dial setting is used for the
IEEE/US curves. The menu is arranged such that if an IEC/UK curve is selected, the I> Time Dial cell is not visible
and vice versa for the TMS setting. For both IEC and IEEE/US type curves, a definite time adder setting is available,
which will increase the operating time of the curves by the set value.
2.1.6

PROGRAMMABLE CURVES

As well as the standard curves as defined by various countries and standardising bodies, it is possible to program
custom curves using the User Programmable Curve Tool, described in the Settings Application Software chapter.
This is a user-friendly tool by which you can create curves either by formula or by entering data points.
Programmable curves help you to match more closely the withstand characteristics of the electrical equipment
than standard curves.
2.2

PRINCIPLES OF IMPLEMENTATION

The range of protection products provides a very wide range of protection functionality. Despite the diverse range
of functionality provided, there is some commonality between the way many of the protection functions are
implemented. It is important to describe some of these basic principles before going deeper into the individual
protection functions.
A simple representation of protection functionality is shown in the following diagram:
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Chapter 6 - Current Protection Functions
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