GE Multilin g60, Instruction Manual

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GE Multilin G60 Generator Protection System 3-39
3 HARDWARE 3.3 DIRECT INPUT AND OUTPUT COMMUNICATIONS MODULES
3
Figure 3–44: G.703 AND FIBER INTERFACE CONNECTION
3.3.8 IEEE C37.94 INTERFACE
The UR-series IEEE C37.94 communication modules (modules types 2G, 2H, 76, and 77) are designed to interface with
IEEE C37.94 compliant digital multiplexers or an IEEE C37.94 compliant interface converter for use with direct input and
output applications. The IEEE C37.94 standard defines a point-to-point optical link for synchronous data between a multi-
plexer and a teleprotection device. This data is typically 64 kbps, but the standard provides for speeds up to 64
n kbps,
where n = 1, 2,…, 12. The UR-series C37.94 communication modules are either 64 kbps (with n fixed at 1) for 128 kbps
(with n fixed at 2). The frame is a valid International Telecommunications Union (ITU-T) recommended G.704 pattern from
the standpoint of framing and data rate. The frame is 256 bits and is repeated at a frame rate of 8000 Hz, with a resultant bit
rate of 2048 kbps.
The specifications for the module are as follows:.
• IEEE standard: C37.94 for 1 × 128 kbps optical fiber interface (for 2G and 2H modules) or C37.94 for 2 × 64 kbps opti-
cal fiber interface (for 76 and 77 modules)
• Fiber optic cable type: 50 nm or 62.5 µm core diameter optical fiber
• Fiber optic mode: multi-mode
• Fiber optic cable length: up to 2 km
• Fiber optic connector: type ST
• Wavelength: 820 ±40 nm
• Connection: as per all fiber optic connections, a Tx to Rx connection is required
The UR-series C37.94 communication module can be connected directly to any compliant digital multiplexer that supports
the IEEE C37.94 standard as shown below.
Rx2
Tx2
842778A2.CDR
~3b
75, 7E, 7F
, 7G,
and 7Q
Rx +
Shield
Tx –
Rx –
Tx +
G.703 communications
~2b
~1b
~1a
~3a
~2a
G.703
channel 1
Surge
Fiber
channel 2
UR-series
device
IEEE C37.94
fiber interface
up to 2 km
842755A2.CDR
Digital
multiplexer,
IEEE C37.94
compliant