Toshiba GRZ100-211B, Instruction Manual

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Transmission Format in Integral Digital Communication
Figure P-1 shows the data transmission format that applies to the data transmission between relays
at the terminals of the transmission lines. The individual parts of the transmission format are
described below.
(1) Frame header
Indicates the start of a frame.
(2) Analog value (positive-sequence current and voltage) for fault locator
12 bits sent every three frames (I
1
at remainder 0 of SA, I
1
’ at remainder 1 of SA, V
1
at
remainder 2 of SA).
(3) SA flag and control data
Device data (CB,DS) and control data necessary for the protective function are transmitted by
sub-communication. Sub-communication is used for signals that may be transmitted at low
speed, and has the effect that 1-bit information is different from frame to frame.
Frames are identified by the SA flag, which is also transmitted by sub-communication. It
detects the signal pattern of 00001 and identifies a frame number. One cycle of frame
numbers covers 12 frames.
(4) SP flag and time data
The SP flag and time data for sampling time synchronization are transmitted by
sub-communication. Sub-communication detects the signal pattern of 00001 and identifies a
frame number.
The time data for sampling time synchronization has 16 bits.
(5) CRC (Cyclic Redundancy Check) data
CRC data is added to check transmitted data for transmission errors.
Data without the frame header is divided by a polynomial and the resultant remainder is
transmitted as the CRC data.
On the receiving side, the CRC data is subtracted from the transmitted data, the result divided
by the same polynomial, and the remainder checked for 0.
Polynomial: X
16
+
X
12
+
X
5
+
1
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