Protective Elements
InEn - Inadvertent Energization [50/27]
InEn
What does inadvertent energization mean?
Inadvertent energization of a synchronous generator means, that the stator winding of the generator is connected to
the power system accidentally/unintendedly.
Inadvertent energization may be caused by the following events:
Malfunctions within the control circuits
Flashovers within the breaker -especially large generators (high voltages)
Gen-set control malfunctions
Mistakes by operators
What are the serious consequences of inadvertent energization?
If a synchronous generator that stands still or is close to standstill is energized inadvertent, then the generator will
be accelerated like an induction machine. If a synchronous generator is energized while he stands still or is close to
standstill, high currents will flow, similar to starting currents of a starting induction machine. As a consequence of
that the armature/rotor winding or even the entire gen-set might be damaged within seconds.
How to prevent inadvertent energization?
By means of a special logic that evaluates overcurrent, undervoltage and/or the state of the breaker. See block
diagram.
The inadvertent energization is an overcurrent element that is released or blocked by a logic. The logic comprises a
pickup and a dropout timer. The logic can be applied in two different variants to detect, that the generator is taken
out of service:
»Undervoltage«
and »
Breaker status Open«
or
»Undervoltage«
or »
Breaker Status«
By means of the »
Arming Signal«
, the user can choose between those two above mentioned options. The OR-Logic
might be used if the voltage transformers are mounted on the line side.
792 MCDGV4 DOK-HB-MCDGV4-2E
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