Ieee C37.94 Interface - GE G60 Instruction Manual

3.3 DIRECT I/O COMMUNICATIONS
The UR-series IEEE C37.94 communication modules (76 and 77) are designed to interface with IEEE C37.94 compliant
digital multiplexers and/or an IEEE C37.94 compliant interface converter for use with direct input/output applications for
firmware revisions 3.30 and higher. 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) 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 × 64 kbps optical fiber interface
Fiber optic cable type: 50 mm or 62.5 mm core diameter optical fiber
3
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 any 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.
The UR-series C37.94 communication module has six (6) switches that are used to set the clock configuration. The func-
tions of these control switches is shown below.
3-30
UR series
relay
IEEE C37.94
Fiber Interface
UR series
relay
up to 2 km
Internal Timing Mode
te te
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
1
2
3
4
5
6
G60 Generator Management Relay
IEEE C37.94
Fiber Interface
up to 2 km
RS422
Interface
IEEE C37.94
Converter
Loop Timed
ON
xt te xt te xt te xt te
xt xt xt xt
1 2 3 4
Loop Timed
ON OFF
ON OFF
OFF OFF
OFF OFF
OFF OFF
OFF OFF
3 HARDWARE

3.3.8 IEEE C37.94 INTERFACE

Digital
Multiplexer
IEEE C37.94
compliant
Digital
Multiplexer
with EIA-422
Interface
ON
xt te xt te
OFF
xt xt
5 6
GE Multilin