IN
6.3 IRIG-B connections (P741 only)
The IRIG-B input and BNC connector have a characteristic impedance of 50Ω. It is
recommended that connections between the IRIG-B equipment and the relay are made
using coaxial cable of type RG59LSF with a halogen free, fire retardant sheath.
6.4 RS232 port
Short term connections to the RS232 port, located behind the bottom access cover, can be
made using a screened multi-core communication cable up to 15m long, or a total
capacitance of 2500pF. The cable should be terminated at the relay end with a 9-way, metal
shelled, D-type male plug.
6.5 Optical fiber connectors (when applicable)
WARNING ABOUT LASER RAYS: Where fibre optic communication devices are fitted,
never look into the end of a fiber optic due to the risk of causing serious damage to the eye.
Optical power meters should be used to determine the operation or signal level of the device.
Non–observance of this rule could possibly result in personal injury.
If electrical to optical converters are used, they must have management of character idle
state capability (for when the fibre optic cable interface is "Light off").
Specific care should be taken with the bend radius of the fibres, and the use of optical shunts
is not recommended as these can degrade the transmission path over time.
The relay uses 1300nm multi mode 100BaseFx and BFOC 2.5 - (ST)® connectors (one Tx –
optical emitter, one Rx – optical receiver).
6.6 Download/monitor port
Short term connections to the download/monitor port, located behind the bottom access
cover, can be made using a screened 25-core communication cable up to 4m long. The
cable should be terminated at the relay end with a 25-way, metal shelled, D-type male plug.
6.7 Earth connection
Every relay must be connected to the local earth bar using the M4 earth studs in the bottom
left hand corner of the relay case. The minimum recommended wire size is 2.5mm
2
and
should have a ring terminal at the relay end. Due to the limitations of the ring terminal, the
maximum wire size that can be used for any of the medium or heavy duty terminals is
6.0mm
2
per wire. If a greater cross-sectional area is required, two parallel connected wires,
each terminated in a separate ring terminal at the relay, or a metal earth bar could be used.
Note: To prevent any possibility of electrolytic action between brass or copper earth
conductors and the rear panel of the relay, precautions should be taken to isolate them from
one another. This could be achieved in a number of ways, including placing a nickel-plated
or insulating washer between the conductor and the relay case, or using tinned ring
terminals.
Before carrying out any work on the equipment, the user should be familiar with the
contents of the safety section/safety guide Pxxx-SG-4LM-2 or later issue, the technical
data section and the ratings on the equipment rating label.”
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