KROHNE H250 M40 ATEX II2G Ex i EN - Manual (Page 17)

ELECTRICAL CONNECTIONS
4
17
H250 M40
www.krohne.com 08/2012 - 4001481101 MA H250/M40-Ex-II2G-AD R01 en
Electrical connections
4.1 General notes
The built-in equipment is connected electrically in the integrated terminal compartment of the
display. The circuits are designed in protection type "intrinsically safe".
The connecting cables should be selected according to the applicable installation standards (e.g.
EN 60079-14) and the maximum operating temperature. Ensure that no residual current can
form between separate intrinsically safe signal circuits.
• The connecting cables must be fixed and laid so they are sufficiently protected against
damage.
• All cores that are not used must be securely connected to the earth potential of the
hazardous area or carefully insulated against each other and against ground (test voltage ≥
500 V
eff
).
• Lay cables so as to ensure that there is sufficient distance between surfaces of the
measuring unit and the connecting cable.
• Supplied blind plugs / cable entries guarantee protection against foreign bodies and water
(protection category) IP66 / 67 according to EN 60529 in the temperature range
T
amb
= -40...+100°C / -40...+212°F.
• The outer diameter of the connecting cable must be within the sealing range of the cable
entry (8...13 mm / 0.31...0.51").
• Unused cable entries are to be closed (>IP66 / 67).
Ensure that the seals and cut seals are tight.
4.2 Power supply
The variable area flowmeter does not require a separate power supply. The required supply for
the built-in electronics is provided via the 4...20mA current output and the bus connection.
4.3 Inputs/outputs
The terminal assignment of the built-in electrical equipment is described in the Standard
Installation and Operation Instructions. The variable area flowmeter signal circuits may only be
connected to certified intrinsically safe slave units or circuits. For more information see chapter
"Electrical data"
4.4 Grounding and equipotential bonding
If the device is not sufficiently electrostatically grounded via the process cables, an additional
earth connection must be established using the ground terminal. The ground terminal on the
gate of the cable entry of the display guarantees an electrostatic connection of the device and
complies with the requirements of an equipotential bonding connection.
Any existing cable shields should be connected to earth according to applicable installation
regulations (EN 60079-14). A terminal connection in the terminal compartment permits a short
way earthing of the cable shields.
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