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Protection and Control of Modern Power Systems

Table 1 Overcurrent relay characteristics coefficient, according to IEC-60255 std

From: Coordination of dual setting overcurrent relays in microgrid with optimally determined relay characteristics for dual operating modes

Characteristic curve of relay

α

β

Relay characteristics identifier (RCI)

Very inverse (VI)

13.5

1

1

Extremely inverse (EI)

80

2

2

Normal inverse (NI)

0.14

0.02

3

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