Chapter 4) 7SR23 DAD Data Communications
©2013 Siemens Protection Devices Limited
Chapter 4 Page 8 of 54
2.1.3 Optional Rear Fibre Optic Interfaces (COM3 and COM4)
When connecting via the optional fibre optic interface the selection of fibre-optic cable is important. Fibres must
be terminated with ST
TM
(BFOC/2.5) connectors.
The recommended type is 62.5/125µm glass fibre. Communication distances over 1 km are achievable using this
type of fibre.
The fibre optic data comms link will be interrupted if the relay element is withdrawn from the case.
A budget loss calculation should be made for all installations. The following table gives the launch power and
receiver sensitivity of each of the fibre optic communication ports on the Argus M relay when used with specific
fibre optic types.
Tx Launch Power (dB)
RX Receive Sensitivity (dB)
Fibre Type
Min
Max
Min
Max
62.5/125µm
-11.7
-15.7
-24
-9.2
1mm Polymer
-6.4
-10.4
-24
-9.2
200µm PCS
-2.8
-6.8
-24
-9.2
Factors to be considered when calculating fibre-optic transmission distances:
Transmitter launch power
Attenuation, based on light frequency, fibre material and fibre diameter
Number of intermediate connectors and splices
Receiver sensitivity
The light power at the receiver must be above the sensitivity of the receiver in order that effective communication
can occur.
Fibre cables are supplied on reels of finite length which may necessitate additional jointing.
Typical losses at connectors are 0.5-1.0dB each. This allows for normal age related deterioration. Consult
manufacturers data for actual values.
Typical Splice losses are <0.3dB.
A 3dB safety margin is usually allowed after the budget calculation is performed.
Following installation and prior to putting into service the actual losses should be measured for each fibre using a
calibrated light source and meter. Measured and calculated values can be compared.
Summary of Contents for 7SR23 DAD
Page 1: ...Answers for energy 7SR23 DAD High Impedance Protection Relay Reyrolle Protection Devices ...
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Page 4: ...7SR23 DAD Contents 2013 Siemens Protection Devices Limited ...
Page 60: ...Chapter 3 7SR23 DAD Performance Specification 2013 Siemens Protection Devices Limited ...
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