ABB Relion 670 series - Direct transfer trip logic; Introduction

13.8 Direct transfer trip logic
13.8.1 Introduction
Direct transfer trip (DTT) logic is used together with Line distance protection function
or other type of line protection. One typical example for use of transfer trip is given
below. When Line distance protection function is extended to cover power lines
feeding the transformer directly and there is a fault in transformer differential area, the
transformer differential protection operates faster than line protection. A trip command
is sent to the remote end of the line. On remote end, before sending a trip command to
the circuit breaker, the certainty of a fault condition is ensured by checking local
criterion in DTT logic.
~
I
DIFF
>
Load
DTT
CSCR TRIP
TRIP
VT1
CT3CT2CT1
Power
Transformer
Line
X
source
Source
en03000120.vsd
IEC03000120 V1 EN
Figure 413: Direct transfer trip
On receiving the CR signal from remote end, Direct transfer trip logic needs to check
additional local criterion, before sending the trip signal to circuit breaker.
DTT logic can be handled in the following separate application functions:
1. Low active power and power factor protection LAPPGAPC (37_55)
2. Sudden change in current variation SCCVPTOC (51)
3. Compensated over and undervoltage protection COUVGAPC (59_27)
4. Carrier receive logic LCCRPTRC (94)
5. Zero sequence overvoltage protection LCZSPTOV (59N)
6. Negative sequence overvoltage protection LCNSPTOV (47)
7. Zero sequence overcurrent protection LCZSPTOC (51N)
8. Negative sequence overcurrent protection LCNSPTOC (46)
9. Three-phase overcurrent LCP3PTOC (51)
10. Three-phase undercurrent LCP3PTUC (37)
A composite scheme of these functions must be configured in PCM600 configuration
tool, to make a complete DTT scheme as shown in Figure
414. The different individual
Section 13 1MRK505222-UUS C
Scheme communication
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Technical reference manual