breakers in case the own breaker fails to open. CCRBRF can be
current based, contact based, or an adaptive combination of
these two conditions.
Current check with extremely short reset time is used as check
criterion to achieve high security against inadvertent operation.
Contact check criteria can be used where the fault current
through the breaker is small.
Breaker failure protection, 3-phase activation and output
(CCRBRF) current criteria can be fulfilled by one or two phase
currents the residual current, or one phase current plus residual
current. When those currents exceed the user defined settings,
the function is triggered. These conditions increase the security
of the back-up trip command.
CCRBRF function can be programmed to give a three-phase
re-trip of the own breaker to avoid inadvertent tripping of
surrounding breakers.
Pole discordance protection CCRPLD
Circuit breakers and disconnectors can end up with the phases
in different positions (close-open), due to electrical or
mechanical failures. An open phase can cause negative and
zero sequence currents which cause thermal stress on rotating
machines and can cause unwanted operation of zero sequence
or negative sequence current functions.
Normally the own breaker is tripped to correct such a situation.
If the situation persists the surrounding breakers should be
tripped to clear the unsymmetrical load situation.
The pole discordance function operates based on information
from the circuit breaker logic with additional criteria from phase
selective current unsymmetry.
Directional over/underpower protection GOPPDOP/
GUPPDUP
The directional over-/under-power protection GOPPDOP/
GUPPDUP can be used wherever a high/low active, reactive or
apparent power protection or alarming is required. The
functions can alternatively be used to check the direction of
active or reactive power flow in the power system. There are a
number of applications where such functionality is needed.
Some of them are:
• detection of reversed active power flow
• detection of high reactive power flow
Each function has two steps with definite time delay.
Negative sequence based overcurrent function DNSPTOC
Negative sequence based overcurrent function DNSPTOC is
typically used as sensitive earth-fault protection of power lines,
where incorrect zero sequence polarization may result from
mutual induction between two or more parallel lines.
Additionally, it is applied in applications on cables, where zero
sequence impedance depends on the fault current return
paths, but the cable negative sequence impedance is
practically constant.
The directional function is current and voltage polarized. The
function can be set to forward, reverse or non-directional
independently for each step. Both steps are provided with a
settable definite time delay.
DNSPTOC protects against all unbalanced faults including
phase-to-phase faults. The minimum start current of the
function must be set to above the normal system unbalance
level in order to avoid unwanted operation.
7. Voltage protection
Two step undervoltage protection UV2PTUV
Undervoltages can occur in the power system during faults or
abnormal conditions. Two step undervoltage protection
(UV2PTUV) function can be used to open circuit breakers to
prepare for system restoration at power outages or as long-
time delayed back-up to primary protection.
UV2PTUV has two voltage steps, where step 1 is settable as
inverse or definite time delayed. Step 2 is always definite time
delayed.
UV2PTUV has a high reset ratio to allow settings close to
system service voltage.
Two step overvoltage protection OV2PTOV
Overvoltages may occur in the power system during abnormal
conditions such as sudden power loss, tap changer regulating
failures, and open line ends on long lines.
Two step overvoltage protection (OV2PTOV) function can be
used to detect open line ends, normally then combined with a
directional reactive over-power function to supervise the
system voltage. When triggered, the function will cause an
alarm, switch in reactors, or switch out capacitor banks.
OV2PTOV has two voltage steps, where step 1 can be set as
inverse or definite time delayed. Step 2 is always definite time
delayed.
OV2PTOV has a high reset ratio to allow settings close to
system service voltage.
Two step residual overvoltage protection ROV2PTOV
Residual voltages may occur in the power system during earth
faults.
Two step residual overvoltage protection ROV2PTOV function
calculates the residual voltage from the three-phase voltage
input transformers or measures it from a single voltage input
transformer fed from an open delta or neutral point voltage
transformer.
Transformer protection RET650
1MRK 504 137-BEN B
Product version: 1.3
16
ABB
