GENERAL INSTRUCTIONS FOR CTC
UNDER POLE COMPACT
TRANSFORMER SUBSTATION
IG-086-GB
version 02
11.07.2007
Page 13 of 20
The copper connector cross-section, the contact surface of terminals and tightening torques
shall be suitable for a default current delimited by Network protections.
In the cases when it is not feasible to maintain the values of step and touch voltages within
the limits specified in Supplementary Technical Instruction MIE-RAT 13 of the Transformer
Substations Regulations (R.D. 3275/1982 and updates), the owner of the facilities shall
implement at least one of the additional safety measures provided in this instruction, in order
to reduce the risks to persons and assets.
The recommended tightening torque for the electrical connections of the earthing network is
described on the table below:
TIGHTENING TORQUE [Nm]
METRIC
Steel 8.8
Stainless A2
M8
21
M10
38
M12
60
3530
1000
1000
1330
43
70
10
00
10
00
21
70
IMPORTANT
It is recommended to make a 50 mm2 bare
copper loop without interruption. Use a
conductor prolonged to the inside of the
transformer substation to connect to the
disconnection box of the protection earthing
circuit.
Dimensions in millimetres
Figure 3.5
:
Recommended Earthing Ring
437
0
1000
217
0
100
0
100
0
1330
3530
1000
