on the disconnected part of the line. The
primary line distance protection will thus not
be able to operate and must be blocked.
The stub protection STBPTOC (50STB) covers
the zone between the current transformers and
the open disconnector. The three-phase
instantaneous overcurrent function is released
from a normally open, 89b auxiliary contact on
the line disconnector.
Pole discordance protection CCRPLD
(52PD)
Circuit breakers and disconnectors can end up
with their phase poles 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 affected breaker is tripped to
correct such a situation. If the situation
warrants the surrounding breakers should be
tripped to clear the unsymmetrical load
situation.
The pole discrepancy function operates based
on information from the circuit breaker logic
with additional criteria from unsymmetrical
phase currents when required.
Broken conductor check BRCPTOC
(46)
Conventional protection functions can not
detect the broken conductor condition. Broken
conductor check (BRCPTOC, 46) 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
(32/37)
The directional over-/under-power protection
GOPPDOP (32)/GUPPDUP (37) 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 (46)
Negative sequence based overcurrent function
(DNSPTOC, 46) may be used in power line
applications where the reverse zero sequence
source is weak or open, the forward source
impedance is strong and it is desired to detect
forward ground faults.
Additionally, it is applied in applications on
underground 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 (46) protects against all unbalanced
faults including phase-to-phase faults. The
minimum pickup current of the function must
be set to above the normal system unbalance
level in order to avoid unintentional tripping.
Breaker protection REQ650 ANSI
1MRK 505 269-BUS -
Product version: 1.1
Issued: April 2011
18
ABB
