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

Capacitive electrodes EL - Profibus PA 27
Electrical connection
Connection example for installation of an Ex system on vessels with cathodic cor-
rosion 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
ground terminal
Sensor
Screen
Overvoltage-
arrester
in metal or
plastic housing
Screen
Non-Ex area
Switching cabinet/Control room
Signal
condition-
ing
instrument
or
safety
barrier
optionally overvoltage
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, screening or metallic protection tube according to VDE must be used
between overvoltage arrester and transmitter (metal cover, screening or protective tube must not be
grounded).
Test voltage of the cable "A"
≥
1500 V AC.
B
A cable acc. to VDE, if necessary with metal cover or screen, must be used between control room and
overvoltage arrester. Metal cover or screen - 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.