Answer / omar aziz

Every electrical equipment installed in a power system has
an I2t rating. Eg(20kA for 1sec) This indicates the maximum
permissible energy that the equipment can withstand before
blowing into bits. Protection co ordination must ensure
that this damagiong curve is always protected by the
protection system. This is Energy based coordination.

Time based coordinaation is when no energy basis are
required but time selection is picked for personnel safety
reasons and not equipment damage reasons

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