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 unsymmetrical phase
currents when required.
Broken conductor check BRCPTOC
Conventional protection functions can not detect
the broken conductor condition. Broken
conductor check (BRCPTOC) function, consisting
of continuous current unsymmetrical check on the
line where the IED is connected will give alarm or
trip at detecting broken conductors.
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. Reset times for both steps can be set as
well.
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.
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.
5. 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.
Two step overvoltage protection OV2PTOV
Overvoltages may occur in the power system
during abnormal conditions such as sudden
power loss, tap changer regulating failures, open
line ends on long lines etc.
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 an extremely 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.
Breaker protection REQ650
1MRK 505 283-BEN -
Product version: 1.2
ABB 19
To Next Page
Loading...
