Hitachi Relion 670 Series Applications Manual page 293

1MRK506375-UEN Rev. N
Document
revision
L
M
N
13.3.2 Identification
Function description
Scheme communication logic for
residual overcurrent protection
13.3.3 Application
To achieve fast fault clearance of earth faults on the part of the line not covered by the instantaneous
step of the residual overcurrent protection, the directional residual overcurrent protection can be
supported with a logic that uses communication channels.
One communication channel is used in each direction, which can transmit an on/off signal if required.
The performance and security of this function is directly related to the transmission channel speed
and security against false or lost signals.
In the directional scheme, information of the fault current direction must be transmitted to the other
line end.
With directional comparison in permissive schemes, a short operate time of the protection including a
channel transmission time, can be achieved. This short operate time enables rapid autoreclosing
function after the fault clearance.
The communication logic module enables blocking as well as permissive under/overreaching
schemes. The logic can also be supported by additional logic for weak-end infeed and current
reversal, included in the Current reversal and weak-end infeed logic for residual overcurrent
protection (ECRWPSCH) function.
Metallic communication paths adversely affected by fault generated noise may not be suitable for
conventional permissive schemes that rely on signal transmitted during a protected line fault. With
power line carrier, for example, the communication signal may be attenuated by the fault, especially
when the fault is close to the line end, thereby disabling the communication channel.
To overcome the lower dependability in permissive schemes, an unblocking function can be used.
Use this function at older, less reliable, power line carrier (PLC) communication, where the signal has
to be sent through the primary fault. The unblocking function uses a guard signal CRG, which must
always be present, even when no CR signal is received. The absence of the CRG signal during the
security time is used as a CR signal. This also enables a permissive scheme to operate when the
line fault blocks the signal transmission. Set the tSecurity to 35 ms.
13.3.4 Setting guidelines
The parameters for the scheme communication logic for residual overcurrent protection function are
set via the local HMI or PCM600.
Railway application RER670
Application manual
Product History
revision
2.2.5 Added separate DOs for teleprotection permissive (TxPrm & RxPrm1), blocking (TxBlk &
RxBlk1) and direct trip (TxTr & RxTr1) transmit and receive signals in accordance with
61850 Ed 2.0.
2.2.6 -
2.2.6 -
IEC 61850
identification
ECPSCH
© 2017 - 2023 Hitachi Energy. All rights reserved
IEC 60617 ANSI/IEEE C37.2
identification device number
- 85
Section 13
Scheme communication
M14882-1 v2
M13919-3 v6
M13920-4 v7
287