GE N60 - Ieee C37.94 Interface

3-30 N60 Network Stability and Synchrophasor Measurement System GE Multilin
3.3 DIRECT INPUT AND OUTPUT COMMUNICATIONS 3 HARDWARE
3
AWG 20-24 twisted shielded pair is recommended for external RS422 connections and ground the shield only at one end.
For the direct fiber channel, address power budget issues properly.
When using a LASER Interface, attenuators can be necessary to ensure that you do not exceed
maximum optical input power to the receiver.
Figure 3–38: RS422 AND FIBER INTERFACE CONNECTION
Connections shown above are for multiplexers configured as DCE (data communications equipment) units.
3.3.8 IEEE C37.94 INTERFACE
The UR-series IEEE C37.94 communication modules (modules types 2G, 2H, 2I, 2J, 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
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 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 mm or 62.5 mm core diameter optical fiber
• Fiber optic mode: multimode
• 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 shown as follows.
NOTICE
Tx2
Rx2
842777A2.CDR
~8a
7L, 7M, 7N,
7P, and 74
Shield
Tx –
Rx –
Tx +
Rx +
RS422 communications
~4b
~3a
~3b
~6a
~2a
RS422
channel 1
Surge
+
–
~7a
~8b
Clock
channel 1
Common
~2b
COM
Fiber
channel 2
UR-series
device
IEEE C37.94
fiber interface
up to 2 km
842755A2.CDR
Digital
multiplexer,
IEEE C37.94
compliant