ABB CI546 3BSE012545R1 communication unit
Synchrocheck
The synchrocheck function determines the difference between the amplitudes, phase
angles and frequencies of two voltage vectors. The synchrocheck function also contains
checks for dead line and dead bus.
Transformer differential protection
• For two- and three-winding transformers
• Auto transformers
• Three-phase function
• Current-adaptive characteristic
• High stability for external faults and current
transformer saturation
• No auxiliary transformers necessary
because of vector group and CT ratio compensation
• Inrush restraint using 2nd harmonic
The transformer differential protection function
can also be used as an autonomous T-zone
protection in a 1½ breaker scheme.
Thermal overload
This function protects the insulation against
thermal stress. This protection function is normally equipped with two independently set
levels and is used when oil overtemperature
detectors are not installed.
Peak value over- and undercurrent protection
These functions are used for current monitoring with instantaneous response and where
insensitivity to frequency is required.
Peak value over- and undervoltage protection
This function is used for voltage monitoring
with instantaneous response and where insensitivity to frequency is required.
Frequency function
The function is used either as an over-/ underfrequency protection, or for load-shedding in
the event of an overload. Several stages of
the frequency protection are often needed.
This can be achieved by configuring the frequency function several times.
Rate of change frequency protection df/dt
This function is used for the static, dynamic
and adaptive load-shedding in power utilities
and industrial distribution systems. The function supervises the rate-of-change df/dt of one
voltage input channel. Several stages of the
rate-of-change frequency protection are often

needed. This can be achieved by configuring
the rate-of-change frequency function several
times.
Definite time overfluxing protection
This function is primarily intended to protect
the iron cores of transformers against excessive flux. The function works with a definite
time delay. The magnetic flux is not measured
directly. Instead the voltage/frequency-ratio,
which is proportional to the flux is monitored.
Inverse time overfluxing protection
This function is primarily intended to protect
the iron cores of transformer against excessive flux. The function works with an inverse
time delay. The inverse curve ca be set by a
table of 10 values and the times t-min and tmax. The magnetic flux is not measured directly. Instead the voltage/frequency-ratio,
which is proportional to the flux is monitored.
Power function
This function provides single, or three phase
measurement of the real or apparent power.
The function can be configured for monitoring
reverse, active or reactive power (power
direction setting). Phase angle errors of the
CT/VT inputs can be compensated by setting.
The operating mode can be configured either
to underpower or to overpower protection.
Logics and delay/integrator
These functions allow the user the engineering of some easily programmable logical functions and are available as standard also in the
REB500 functionality.
Directional sensitive earth fault protection
for grounded systems
A sensitive directional ground fault function
based on the measurement of neutral current
and voltage is provided for the detection of
high-resistance ground faults in solidly or lowresistance grounded systems. The scheme
operates either in a permissive or blocking
mode and can be used in conjunction with an
inverse time earth fault overcurrent function.
In both cases the neutral current and voltage
can be derived either externally or internally.
This function works either with the same communication channel as the distance protection
scheme or with an independent channel.
Directional sensitive earth fault protection
for ungrounded or compensated systems
The sensitive earth fault protection function for
ungrounded systems and compensated systems with Petersen coils can be set for either