WIKA FLM - Handbuch (Seite 13)

GB
WIKA operating instructions level sensor model FFG 13
13445627.01 12/2010 GB/D/F
5. Electrical connection
The level sensor in areas exposed to danger of explosion
are allowed to be connected to buffer amplifiers only if these
are certificated by a generally accepted test institute, and
if the electric specifications thereof are compliant with the
following conditions:
Ui = ≤ 30 V
Ii = ≤ 0.2 A
Pi = ≤ 1 W
Level sensor model FFG
(Standard and pharmaceutical design) EEx ia
The electric specifications (see product label) and the additional provisi-
ons for installing intrinsically safe circuits should be abided by. No work
is allowed to be carried out unless by trained experts.
The electric connection of the level sensor is via built-in clamps. The
given connecting pattern is conveyed by the connection diagram within
the interior of the terminal box, or by the mounting and operating instruc-
tions.
Selection of connection cable
Wiring requires a 2-core cable to be connected in the
probe head of the sensor. The cable cross-section must be
selected so that the supply voltage on the level sensor is no
less than 10 V in the borderline case of maximum current
consumption (21.5 mA) in a given cable length L.
A copper cable with a cable cross-section of 1 mm² and a
length of 100 m (100 m forward and 100 m return line) has a
resistance of 3.4 Ω (R = 0.034 Ω x L(m)/F(mm²).
5. Electrical connection