Installation
Connection
Beck GmbH
Druckkontrolltechnik
Ferdinand-Steinbeis-Straße 4
71144 Steinenbronn
Operating instructions – Pressure Switch - Model-930...EX Rev.9
Page 8 of 18
Power supply
Each intrinsically safe operating material must have an associated
operating material inserted before it, outside of the potentially
explosive zone:
Pay attention to maximum characteristics (U, I, P, L, C):
Compare the information on the specification plate of the appropriate
equipment and the pressure switch 930..EX
Select connecting cables
The following points must be observed when selecting the cable:
Select cable material that complies with the local resistance
requirements (mechanical, chemical)
The outer diameter may be from 5 to 9 mm
Cable cross-section in accordance with electrical power and data sheet
The following points must be observed when selecting cables for intrinsically safe power
circuits:
Diameter of individual conductors: greater than 0.1mm
Insulation strength of the individual wires: greater than 0.2 mm
Test voltage for intrinsically safe cables:
- between wires, shield and earth: 500V AC
Shield: The shield area must be 60% of the surface coverage or twisting
Labelling of intrinsically safe power circuits: colour preferably light blue
L and C cable characteristics must be available
(C
i
=110nF/km; L
i
=1 mH/km)
Cable routing
If there is a risk of mechanical damage, the cable must be provided with additional
protection (protective tube etc.)
The cable diameter must be complied with in order to provide a tight connection in
the cable lead-in.
The screwed cable connection and the screws of the housing cover must be tight-
ened in order to comply with the IP protection class. Over-tightening damages the
housing.
Connecting the cable
Please ensure that the cables that are being connected are not live.
otherwise there is a risk of igniting a potentially explosive atmosphere
Attach the shield
Attach shield at one end (in non-potentially explosive area)
Attach braiding of shield to earth potential over a wide area.
No potential equalisation current must be flowing between potentially
explosive areas and non-potentially explosive areas.
Separation using a capacitor is permitted in this case
for EMC purposes (total max. 10 nF).
Earthing
The external earthing terminal on the housing must be connected
to the potential equalisation of the potentially explosive area with
low resistance
(removal of electrostatic charge between 0.2-1 MOhms is considered to be earthing)
No potential equalisation current must be flowing between potentially explosive are-
as and non-potentially explosive areas
Minimum cross-section: 2 x 1.5 mm² or 1 x 4 mm²
Intrinsically safe power circuits: Housings made from metal do not need to be
earthed.
(If this is necessary anyway – functional earthing, earthing in one location only…)
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