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 dV/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.
There are two conditions for activating the current and voltage delta function.
•
The magnitude of dV/dt exceeds the corresponding value of the
Voltage change rate
setting and magnitude of dI/dt is below the value of the
Current change rate
setting
in any phase at the same time due to the closure of the circuit breaker (
CB_CLOSED
= TRUE).
•
The magnitude of dV/dt exceeds the value of the
Voltage change rate
setting and the
magnitude of dI/dt is below the Current change rate setting in any phase at the same
time and the magnitude of the phase current in the same phase exceeds the
Min Op
current delta
setting.
The first condition requires the delta criterion to be fulfilled in any phase at the same time
as the circuit breaker is closed. Opening the circuit breaker at one end and energizing the
Section 6
1MAC059074-MB A
Supervision functions
868
615 series ANSI
Technical Manual
Summary of Contents for Relion 615 series
Page 1: ... RELION PROTECTION AND CONTROL 615 series ANSI Technical Manual ...
Page 2: ......
Page 39: ...Section 17 Glossary 1181 Table of contents 615 series ANSI 33 Technical Manual ...
Page 40: ...34 ...
Page 64: ...58 ...
Page 216: ...210 ...
Page 884: ...878 ...
Page 1038: ...1032 ...
Page 1136: ...1130 ...
Page 1172: ...1166 ...
Page 1180: ...1174 ...
Page 1186: ...1180 ...
Page 1192: ...1186 ...
Page 1193: ...1187 ...
Page 1194: ......
Page 1195: ......
