Ieee C37.94 Interface - GE t60 Instruction Manual

3 HARDWARE
The UR series IEEE C37.94 communication modules (76 and 77) are designed to interface with IEEE C37.94 compliant
digital multiplexer and/or an IEEE C37.94 compliant interface converter for use with Direct I/O applications on firmware
revision 3.3x. The IEEE C37.94 Standard defines a point to point optical link for synchronous data between a multiplexer
and a teleprotection device. This data is typically 64 kbps but the standard provides for speeds up to 64n kbps, where n = 1,
2, ...12. The UR series C37.94 communication module is 64 kbps only with n fixed at 1. The frame is a valid International
Telecommunications Union (ITU-T) recommendation 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 × 64 kbps optical fiber interface
Fiber optic cable type: 50 mm or 62.5 mm core diameter optical fiber
Fiber optic mode: multi-mode
Fiber optic cable length: up to 2 km
Fiber optic connector: Type ST
Wavelength: 830 ±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 an compliant digital multiplexer that supports
the IEEE C37.94 standard as shown below.
The UR series C37.94 communication module can be connected to the electrical interface (G.703, RS422, or X.21) of a
non-compliant digital multiplexer via an optical-to-electrical interface converter that supports the IEEE C37.94 standard as
shown below.
UR series
relay
The UR series C37.94 communication module has six (6) switches that are used to set the clock configuration. The func-
tions of the control switches is shown below.
GE Multilin
IEEE C37.94
Fiber Interface
UR series
relay
up to 2 km
IEEE C37.94
Fiber Interface
IEEE C37.94
Converter
up to 2 km
Internal Timing Mode
te te
ON
xt xt
te te
xt te xt te xt te xt te
OFF
xt xt xt xt
1 2 3 4 5 6
Switch Internal
ON
1
2 ON
OFF
3
4 OFF
OFF
5
6 OFF
T60 Transformer Management Relay
3.3 DIRECT I/O COMMUNICATIONS

3.3.8 IEEE C37.94 INTERFACE

Digital
Multiplexer
IEEE C37.94
compliant
RS422
Interface
Multiplexer
with EIA-422
Interface
Loop Timed
xt te xt te xt te xt te xt te xt te
xt xt xt xt xt xt
1 2 3 4 5 6
Loop Timed
OFF
OFF
OFF
OFF
OFF
OFF
Digital
ON
OFF
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