Toshiba GR200 Series Instruction Manual page 519

Line differential protection ied

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IEEE C37.94 (N=3)

The IEEE C37.94 (N=3) is provided when the transmission capacity is wider† than the IEEE

(N=1); the DIF_COMM function can also transmit current data at pre-sampling time;

consequently the computation range is extended dynamically. Thus, the computation

performance and accuracy are improved in the differential and other protection functions.

The transmission capacity in the IEEE C37.94 (N=3) is wider than the one in the IEEE

C37.94 (N=1). Followings are added newly when the IEEE C37.94 (N=3) is applied for the

communication:

Current data at pre-sampling time in phase–a, –b, and –c

Residual current data at pre-sampling time

In order to apply for the IEEE C37.94 (N=3) at the channel#1, the user should set Wide for the

scheme switch [CH1_COM_WIDTH].

†Note: Transmission data, which is carried with N=3 extended frame, are made of analog

input quantities that are exclusively entailed in WDE element. For more detail,

Synchronization control

All the IEDs are required to examine the data sampled at the same time and to keep handing

this data at the same address. Thus, the DIF_COMM function has synchronization control

functions that are referred as timing, addressing, delaying, master-and-slave, and re-

synchronization functions. That is, it is not until the entire IEDs start sampling their data

simultaneously. The synchronization control function does not require an external reference

clock or a synchronized internal clock because the channel delay in the telecommunication is

equalized automatically in the IEDs. This equalization method is performed by the master-

and-slave setup and delay compensation technique. These also bring the IED to recover when

the master-and-slave setup function is broken abruptly for the operation. Consequently, the

entire IEDs can stay in their synchronization state as possible.

IEDs arrangement and setup

The synchronization starts when all IEDs are connected. Note that the user is forbidden to

change the IED arrangement while the IEDs operate. This is because, it is impossible to change

all IED arrangements at the same time.

Relay application: CT saturation countermeasure in DIFL

6F2S1914 (0.49)

GRL200 (Soft 033 & 037)

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