5.3 Connecting protective earthing
5.3.1 Connecting protective earthing to relay
Connect the protection relay to earth using a 6 mm
2
(AWG 10) flat braided copper
cable. Use an earth lead of maximum 1.5 m (4.9 ft). Extra length is required for door
mounting.
A 16 mm
2
(AWG 6) flat braided copper cable is recommended for more
demanding EMI environments, such as installations where the relay is
mounted inside a gas insulated switchgear.
1. Using a TX30 screwdriver, loosen the protective earth screw to connect a
separate earth protection lead.
Figure 62: Location of the protective earth pin
Each protection relay must have its own earth lead connected to the
earth circuit connector.
2. Connect the earth lead to the earth bar.
3. Thread the copper cable on the protective earth.
4. Tighten the protective earth screw to 6 Nm ±5% (4.4254 ft-lb ±5%).
5. Support the earth lead so that it cannot break or weaken.
Observe the mechanical, chemical or electrochemical conditions.
Connecting
1MRS759115 E
70 REX640
Installation Manual
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