KROHNE BM 70A EEx EN User Manual
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07/2010 - 4000662402 MA BM70x-Ex-AD-R02-en
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5.2.1.2.
Power cables
The power cables for the non-intrinsically safe power circuits, and for the non-intrinsically safe or
intrinsically safe I/O circuits, shall be selected in keeping with the valid installation standard
(e.g. EN 60079-14 / VDE 0165).
Where elevated product temperatures are involved (see also Sections 3.3.2 and 3.3.3 ”Temperature
Classes”), heat-resistant cables with a continuous service temperature of 80°C shall be provided in
conformity with the type test certificate.
5.2.1.3.
Connection of power and I/O functions
Before connecting or disconnecting the electrical interconnecting cables of the device, make
sure that all cables leading to the signal converter are isolated from the ground (reference
potential) of the hazardous location. This also applies to safety conductors (PE) and
equipotential bonding conductors (PA).
The terminal clamps must be tightened with a torque of 0,7 Nm.
All cores and shields of the power cables not safety-connected to the equipotential bonding
system for the hazardous location should be carefully insulated from each other and from
ground (test voltage 500Vrms for conductors of intrinsically safe cables, test voltage 1500Vrms
for conductors of non-intrinsically safe cables).
Connect all shields by the shortest possible route to the press-fitted U-clamp terminal (FE) in
the terminal compartment. If shields are to be grounded at both ends (e.g. for EMC reasons),
adequate equipotential bonding is required between the two shield ends to avoid unacceptable
equalizing currents
Independent of the type of supply power, the device must be incorporated in the equipotential
bonding system in the hazardous location. This can be done by way of a suitable conductive
connection between the device flange system and the tank. If connection to the equipotential
bonding system is to be made via a separate conductor, this must be connected to the outer
press-fitted U-clamp terminal on the signal converter flange.
Given device versions with intrinsically safe I/O functions (BM 70Ai-Ex and BM 70Pi-Ex), only certified
intrinsically safe equipment with the maximum values (see Section 3.1.4 and Type Test Certificate,
Annex A.1) may be connected to the power terminals marked as being intrinsically safe. This
requirement also applies when the device is not operated in the hazardous location!