H.17
Date Code 20170814
Instruction Manual
SEL-700G Relay
Synchrophasors
C37.118 Synchrophasor Protocol
Table H.12 lists the data settings available on any SEL-700G serial port
(setting SPEED), and the maximum message size that can fit within the port
bandwidth. Blank entries indicate bandwidths of less than 20 bytes.
Referring to Table H.11 and Table H.12, it is clear that the lower SPEED
settings are very restrictive.
The smallest practical synchrophasor message would be comprised of one
digital status word, and this message would consume 24 bytes (includes
frequency and DFDT). This type of message could be sent at any message rate
(MRATE = 60) when SPEED := 38400, as much as MRATE := 5 when
SPEED := 2400, and as much as MRATE := 1 when SPEED := 600.
Another example application has messages comprised of nine synchrophasors,
one digital status word, and two analog values. This type of message would
consume 68 bytes. The 68-byte message could be sent at any message rate less
than or equal to ten (MRATE) when SPEED := 9600.
Protocol Operation
The SEL-700G only transmits synchrophasor messages over serial ports that
have setting PROTO := PMU. The connected device is typically a
synchrophasor processor, such as the SEL-3306. The synchrophasor processor
Table H.11
Size of a C37.118 Synchrophasor Message
Item
Possible Number
of Quantities
Bytes
per
Quantity
Number of Bytes
Minimum
Maximum
Fixed
18
18
Synchrophasors
0–18
4
0
72
Frequency/DFDT
2 (fixed)
2
4
4
Analog Values
0–4
4
0
16
Digital Status Words
0–1
2
0
2
Total (Minimum and Maximum)
22
112
Table H.12
Serial Port Bandwidth for Synchrophasors (in Bytes)
Global Setting
MRATE
Port Setting SPEED
300
600
1200
2400
4800
9600
19200 38400 57600
1
21
42
85
170
340
680
1360
2720
4080
2
21
42
85
170
340
680
1360
2040
4 (60 Hz only)
21
42
85
170
340
680
1020
5
34
68
136
272
544
816
10
34
68
136
272
408
12 (60 Hz only)
28
56
113
226
340
15 (60 Hz only)
21
45
90
181
272
20 (60 Hz only)
34
68
136
204
25 (50 Hz only)
27
54
108
163
30 (60 Hz only)
22
45
90
136
50 (50 Hz only)
27
54
81
60 (60 Hz only)
22
45
68
Summary of Contents for SEL-700G Series
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