To ensure electrical safety in a cable-carrying rack installation, the installation must have suitable electrical continuity. This is stipulated in Standard IEC 61537 section 11.1, which gives the pertinent tests for checking this. This is done in this way: measuring the electrical-resistance values at the most unfavourable point R1 (joining between racks) and R2 (material resistance) measured across two points that are 500 mm apart in the same straight run.
 |
The design of the joint has critical importance in the resistence value R1, as does the material, the surface finish and the method of assembly. Contact between different materials or finishes encourages oxidisation, thereby reducing electrical contunuity. The same condition may arise through insufficient contact pressure at the join point.
DO NOT ASSEMBLES TRAYS AND JOINTS WITH DIFFERENT FINISHES
The maximum admissible values according to IEC 61537 are:
> R1 50 m
<
> R2 5 m
In
tests performed at PEMSA’s request in the Central Laboratory of the Electrical
Engineering Office under number 99 121006 on 10/12/99, involving various samples
of REJIBAND,
the values given in the following tables were found:
|
Rack
mm.
|
Connectors
used and number
|
Tightening
torque at Connectors
|
RESISTANCE
(mý)
|
||||
|
R1
|
R2
|
||||||
|
REJIBAND
|
Z.B.
|
600x60
|
4
connectors
|
 |
3
Nm.
|
0,18
|
0,79
|
|
4
connectors
|
 |
-
|
1,41
|
0,79
|
|||
|
100x60
|
2
connectors
|
|
3
Nm.
|
1,11
|
1,38
|
||
|
2
connectors
|
|
-
|
2,86
|
1,38
|
|||
|
G.C.
|
600x60
|
4
connectors
|
|
3
Nm.
|
1,18 |
0,.73
|
|
|
4
connectors
|
|
-
|
0,39
|
0,73
|
|||
|
INOX
304
|
100x60
|
2
connectors
|
|
3
Nm.
|
2,57
|
4,58
|
|
