ABB Relion REC615, Техническое руководство

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Figure 271: Functional module diagram
Negative phase-sequence criterion
A fuse failure based on the negative-sequence criterion is detected if the measured
negative-sequence voltage exceeds the set
Neg Seq voltage Lev value and the
measured negative-sequence current is below the set
Neg Seq current Lev value.
The detected fuse failure is reported to the decision logic module.
Voltage check
The phase voltage magnitude is checked when deciding whether the fuse failure is a
three, two or a single-phase fault.
The module makes a phase-specific comparison between each voltage input and
the Seal in voltage setting. If the input voltage is lower than the setting, the
corresponding phase is reported to the decision logic module.
Current and voltage delta criterion
The delta function can be activated by setting the
Change rate enable parameter
to "True". Once the function is activated, it operates in parallel with the negative
sequence-based algorithm. The current and voltage are continuously measured in all
three phases to calculate:
• Change of voltage dU/dt
• Change of current dI/dt
The calculated delta quantities are compared to the respective set values of the
Current change rate and Voltage change rate settings.
The delta current and delta voltage algorithms detect a fuse failure if there is a
sufficient negative change in the voltage amplitude without a sufficient change in
the current amplitude in each phase separately. This is performed when the circuit
breaker is closed. Information about the circuit breaker position is connected to the
CB_CLOSED
input.
Supervision functions 1MRS758755 C
536 REC615 & RER615
Technical Manual