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Mounting procedures
– Put the connections in contact with the circuit-breaker terminals.
– Insert a spring washer and a flat washer between the head of the bolt and the connection.
– The flat washers must be of a suitable diameter to distribute the tightening pressure over a large area.
– Tighten the bolt, taking care not to subject the insulating parts to stress. The use of bolts according to DIN class 8.8 standards is recommended,
also making reference to what is indicated in table T2.
– Make sure that the connections do not exert any force on the terminals.
– In case of cable connections, carefully follow the manufacturer's instructions for terminating the cables.
T2
Bolt
Recommended tightening torque (1)
Without lubricant
M6
10 Nm
M8
30 Nm
M10
40 Nm
M12
70 Nm
M16
200 Nm
7.7. Earthing
– For fixed version circuit-breakers, carry out earthing by means of the
special screw marked with the relative symbol. Clean and degrease
the area around the screw to a diameter of about 30 mm.
Use a conductor (busbar or cord) with a cross-section conforming to
the Standards in force.
– When assembly is completed, cover the joint with vaseline grease.
7.8. Connection of the auxiliary circuits
The minimum cross-section of the wires used for the auxiliary circuits
must not be less than the one used for the internal cabling.
Furthermore, they must be insulated for a 2 kV test voltage at power
frequency according to IEC 60694 par. 6.2.10 Standards.
Fig. 9
20
With lubricant (2)
4.5 Nm
10 Nm
20 Nm
40 Nm
80 Nm
(1) The nominal tightening torque is based on a friction coefficient of the thread of
0.14 (distributed value the thread is subjected to which, in some cases, is not
negligible).
The nominal tightening torque with lubricant is according to the DIN 43673 Standards.
(2) Oil or grease. The thread and surfaces in contact with the lubricated heads.
Take into account the deviations from the general Standards table (for example, for
systems in contact or terminals) as foreseen in the specific technical documentation.
The thread and surfaces in contact with the heads of bolts must be slightly oiled or
greased, so as to obtain a correct nominal tightening torque.
7.8.1. Fixed version circuit-breakers
Connection of the circuit-breaker auxiliary circuits must be carried out by
means of modular terminals mounted under the cover.
The wires outside the circuit-breaker must run inside appropriately earthed
metal tubes or ducts.
Before removing the operating mechanism cover to access
the terminal box, make sure that the circuit-breaker is open
and the closing springs discharged.
7.8.2. Circuit-breaker for ABB switchgear
The auxiliary circuits are fully cabled in the factory as far as the connector.
For the external connections, please refer to the electric diagram of the
switchgear.
Fig. 10
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