The principle time sequence of signaling at current reversal is shown.
Protection
Function
Protection
Function
Tele-
Protection
Equipment
Tele-
Protection
Equipment
Tele-
communication
System
CS from the
protection
function, operate
and reset time
CS initiation to
the
communication
system, operate
and reset time
CS propagation,
propagation
CR selection and
decision, operate
and reset time
CR to the
protection
function, operate
and reset time
Time
Fault
occurs
Protection
pick-up CS initiation
CR to
teleprot.
eq.
CR to
prot.
func
Fault current
reversal
Sending
protection
reset
CS to
communication
drop
CR
reception
drop
CR to
prot.
func
drop
Minimum setting of
tDelay
IEC05000536-2-en.vsd
IEC05000536 V2 EN-US
Figure 386: Time sequence of signaling at current reversal
15.7.3.2
Weak-end infeed
M13933-12 v6
The weak-end infeed can be set by setting the parameter
WEI to Off, Echo or Echo & Trip.
Operating zero sequence voltage when parameter
WEI is set to Echo & Trip is set with 3U0>.
The zero sequence voltage for a fault at the remote line end and appropriate fault resistance is
calculated.
To avoid unwanted trip from the weak-end infeed logic (if spurious signals should occur), set
the operate value of the broken delta voltage level detector (3U0) higher than the maximum
false network frequency residual voltage that can occur during normal service conditions. The
recommended minimum setting is two times the false zero-sequence voltage during normal
service conditions.
15.8
Direct transfer trip logic
GUID-F6AE5927-D93F-4CAD-A6C6-445720C806D8 v1
15.8.1
Application
GUID-4D4051FE-B3AC-4394-9234-CC351E95E7F1 v1
The main purpose of the direct transfer trip (DTT) scheme is to provide a local criterion check
on receiving a transfer trip signal from remote end before tripping the local end CB. A typical
application for this scheme is a power transformer directly connected, without circuit breaker,
to the feeding line. Suppose that an internal symmetrical or non-symmetrical transformer fault
appears within the protective area of the transformer differential protection. The line
protection will, in some cases, not recognize the fault. The transformer differential protection
operates for the internal fault and initiates a trip of the secondary side circuit breaker. It also
sends the carrier signal to the remote line end in order to open the line circuit breaker.
Section 15
1MRK 505 343-UEN B
Scheme communication
620
Application manual
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