4
ELECTRICAL CONNECTIONS
10
H250 M10
www.krohne.com
06/2012 - 4001058901- MA H250/M10-Ex-II2G-AD R02 en
Electrical connections
4.1 General notes
Rated values for insulation
•
The insulation of the H.../..../M10 - Ex variable area flowmeters is rated in compliance with
IEC 60 664-1. The following rating parameters are taken into account:
•
Overvoltage category for signal and instrument loops: II
•
Pollution degree of the insulation: 2
Terminal compartment
The electrical connections for the power supply and I/O functions are located in the signal
converter's electronics compartment. The protection type of the electronics compartment is "d".
Unused openings shall be closed in compliance with EN 60079-1. The cables can be routed into
the flameproof electronics compartment in two different ways.
•
Direct entry of the connecting cables by way of approved flameproof cable glands (M20x1.5)
into the flameproof terminal compartment (V
≤
2000cm
³
). The cable glands require a
separate test certificate in accordance with EN 60079-1. Observe the requirements of the test
certificate for the cable glands.
•
Direct entry of the connecting cables by way of conduits into the flameproof enclosed
terminal compartment of the device. Once the conduit has been screwed in, it must form a
flameproof joint with the housing with a minimum thread length of 8 mm. A suitable
mechanical stopping box must be provided in accordance with installation provisions. The
conduit must be installed in compliance with its separate test certificate.
Connecting cables
Connecting cables shall comply with relevant installation standards (e.g., EN 60079-14 / VDE
0165). The outer diameter of the connecting wires shall conform to the cable clamping area for
the supplied cable entries.
The wiring for the variable area flowmeter's electrical connection shall be fixed.
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.
CAUTION!
The IP protection category of the signal converter housing is largely determined by the cable
gland used and the installation.
AD_H250_M10_II2G_R02_en_058901_PRT.book Page 10 Tuesday, June 26, 2012 7:20 AM