VEGA Capacitive electrodes EK Profibus PA - Manual (Page 27)

Capacitive electrodes EK - Profibus PA 27
Electrical connection
Wiring example for the installation of an Ex system on vessels with cathodic
corrosion protection.
The following overvoltage arrester can be used:
----- B62-30 W:
B62-30 W: B62-30 W: B62-30 W: B62-30 W: 9 … 36 V DC, max. 1 A
B A
2
1 E2
E1 A2
A1
B62-30 W
E2
E1 A2
A1
B62-30 W
Ex area, zone 1 or zone 2
oscillator
transmitter
external earth
terminal
sensor
shielding
overvoltage arrester
in metal or plastic
housing
shielding
Non Ex area
switch cabinet/control room
signal
conditioning
instrument
or safety
barrier
optionally: ovevoltae
arrester
vessel zone
0
cathodic tank protection
2 … 24 V (object voltage)
insulated cable min.
4 mm
2 Cu
A
A cable with either metal cover, shielding or metallic protection tube according to VDE must be used
between overvoltage arrester and transmitter (metal cover, shielding or protection tube must be
connected to earth).
Test voltage of the cable "A"
≥
1500 V AC.
B
A cable according to VDE, if necessary with metal cover or shielding must be used between control room
and overvoltage arrester. The metal cover or shielding - if necessary - must only be connected on the
transmitter side of the overvoltage arrester. The cable must have an outer insulation.
Test voltage of the cable "B" ³ 500 V AC.