P341/EN O/B11 Operation Guide
CHAPTER 2 Installation
Page 10/10 MiCOM P341
6.5 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. Chapter 2, Section 3.7 of this manual
details the pin allocations.
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. Chapter 2, Section 3.7 of this manual details the pin allocations.
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.
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