Woodward HighPROtec MCDLV4, Manual

Page: 632 / 1275

Protective Elements
Magnetizing inrush:
Basically, harmonics can be observed and monitored. Due to this fact, the 2 nd and 4 th harmonic are monitored.
Inrush currents depend on the time of energizing, the remnant magnetizing compared to phase of sinusoidal curve,
the voltage (low voltage energizing produce less harmonic), the core material and the core geometry among others.
It is recommended generally to set the harmonic restraint as active.
Stab H2
Default (example)
inactive
Stab H4
Default (example)
inactive
To operate very stably under stationary circumstances, it can be distinguished between a stationary value of
harmonic thresholds and a transient harmonic threshold directly after energizing. This transient period is always
started if the differential as well the restraining current is below 5% of the base current
I
b
. The following values
are recommended for typical cases:
H2 Sta
Default (example)
30%
H2 Tra
Default (example)
15%
H4 Sta
Default (example)
30%
For
CT saturation,
the 5 th harmonic is one typical criteria. This feature also should be activated as long as
CT
saturation
is expected due to
CT
dimensioning and operational current values under external faults. It has to be
noted that
CT saturation
can only be monitored as long as there is a critical rest of the current transformed to the
secondary side of the
CT
. For severe
CT saturation,
the
CT
can be nearly short circuited, as seen from the primary
side, so that nearly no measurable current can be monitored or analyzed.
Stab H5
Default (example)
inactive
H5 Sta
Default (example)
30%
H5 Tra
Default (example)
632 MCDLV4 DOK-HB-MCDLV4-2E