Page 222 - Elpress英文样本电气连接压接系统

Bolt joints

Bolt joints Selection of washers:
• Always select hard flat washers of the
Users/installers of bolted connectors BRB, HB200 type.
always have to adhere to, and follow • The tension washer can normally be
electrical codes and norms in the local excluded. If a tension washer of type DIN
region where they are making such instal- 6796 is used, it must be placed between
lations. The information below is general the screw head/nut and the flat washer. It
and hence, should never be seen as an must never be placed
installation instruction. The installation directly against an electrical
of a terminal with bolt joint for electrical contact surface without a flat washer in
transmission requires special attention. It Bolt joint with spring washer. between. The flat washer must have an
is important that this is done in a correct external diameter at least as large as the
manner, as important as the contact Mounting the terminal against tension washer.
crimping at the other end of the terminal the connection rail • 1 spring washer is sufficient and it should
as described above. The joint must achieve be placed on the rear of the
a sufficiently high clamping force, distribu- Max. 2 terminals of the same size on busbar, between nut and hard flat
ted in a desirable manner and ensure the the same screw. Current load should be washer, see diagram.
electrical properties over a very long time checked. Installation:
under high and varying loads of different • The screws must be tightened with tor-
characteristics. It is very important to fol- Preparatory: que tools so that tightening is
low the installation instructions. These are • Clean contact surfaces from dirt, oxide controlled.
based on theoretical calculations, verified layers and grease using a steel brush and • Torque wrenches must be calibrated
tests and experience from field studies. denatured alcohol. This is especially im- regularly. Oil the screw when installing.
Tightening must be carried out in a con- portant for aluminium. Surfaces that are Even if the torque is recorded correctly,
trolled manner using torque tools, where tinned, nickel-plated, silver plated must the pre-tension force depends entirely on
the relevant screw is tensioned to the not be brushed. the friction.
specified torque. The accuracy of the tool • Petroleum jelly or contact grease reduces • Tightening torque according to the table
is of great importance. The clamping force corrosion risk on cleaned surfaces above. Accuracy better than ±5%.
of a properly tightened screw shall create a • The terminal palm and busbar may be of
contact area large enough to ensure good Fastener selection: different materials.
conductivity, without the risk of overhea- • Screws and nuts of strength class 8.8.
ting. In order for the clamping force to be • Greased galvanized screws provide the Al/Al gives a weaker joint. It is important to
distributed evenly and create a sufficiently least dispersion of the pre-tension force. clean and use contact grease. Tension was-
large contact area, hard flat washers must • Choose stainless A4-80 in environments her + flat washer can reduce the risk
always be used, type BRB HB200 SMS 70, when there is a high risk of corrosion. of settlement.
under screw head and nut. See image Al/Cu gives a higher risk of corrosion
below. This applies regardless of the hard- and settlement, use contact grease.
ness of the conductive materials (which Cu/Al provides low risk of galvanic
are softer than HB200). Otherwise, there is corrosion when the rail is made of Al.
risk of large deformation of the conducting Cu/CU provides the best joint, good
material that reduces the tension, which contact and small risk of settlement.
can increase the risk of inadequate contact
area and overheating.

Recommended tightening torque
Steel Steel Steel Steel Steel Steel
Thread Stainless * Stainless *Stainless *
8.8 * 8.8 * 8.8 * 10.9 * 10.9 * 10.9 *
Bolt joints. - Mv Ff p Mv Ff p Mv Ff P
M5 5,5 6,6 118,0 8,0 9,2 164,0 5,5 6,2 111,0
Tension washers M6 9,5 9,2 114,0 13,0 13,0 160,0 9,5 8,6 107,0
The use of different types of locking M8 23,0 17,0 116,0 32,0 24,0 164,0 22,0 16,0 109,0
elements or spring washers often M10 45,0 27,0 92,0 64,0 38,0 129,0 45,0 25,5 88,0
increases the risk of settlement. If a M12 78,0 40,0 125,0 110,0 56,0 175,0 76,0 37,0 116,0
spring washer of type DIN 6796, M16 200,0 75,0 156,0 280,0 110,0 229,0 185,0 69,0 144,0
with a very high clamping force, is
positioned and secured between e.g. Mv = tightening torque (Nm)
nut and the hard flat washer, it can Ff = pre-tensioning force (kN)
provide an increased margin towards p = flat pressure (N/mm²)
excessively high settlement. FZB = electroplated + gloss chromed
The diameter of the tension washer FZY = electroplated + hard chromed
should be less than or equal to the flat FZM = FZM= mechanically galvanized
washer’s, even after tightening fully. * (FZB, FZY, FZM)
Otherwise, the risk of settlement at the A4/80
outer edge of the flat washer increases
where the clamping forces are concen-
trated. When using spring washers, 1 is
sufficient and it is preferably placed on
the opposite side of the terminal.

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