KROHNE SMARTSENS PH 8xxx Ex EN - Manual (Page 12)

4
ELECTRICAL CONNECTIONS
12
SMARTSENS PH 8XXX
www.krohne.com 07/2014 - 4002951402 - MA SMARTSENS PH 8xxx R02 en
4.4 Grounding and equipotential bonding
To dissipate dangerous electrostatic charges the metal housing must be grounded. The
grounding of SMARTSENS PH 8570 is made through the metal PG thread, which establish the
electrical connection.
SMARTSENS PH 8150 and PH 8320 has to be grounded by the cable shield, because the plastic
PG thread does not make electrical contact with the metal housing. The shield of the sensor
cable should be connected to the ground potential. The electrical connection to the metal
housing and the ground is made by the sensor cable with the connector VP.
When using junction box SJB 200 W-Ex, the shield of the sensor cable must be connected to the
shield connector provided for all SMARTSENS PH 8xxx. This will ensure sufficient electrostatic
grounding and at the same time prevent unacceptably high equalizing currents.
WARNING!
The cable shield must not be connected directly on both ends to the ground potential, since
unacceptably high equalizing currents can flow at potential differences.
INFORMATION!
On junction box type SJB 200 W-Ex, the shield connector is connected to the ground potential via
a 1 megohm resistor and a capacitor in parallel.
The connections for the intrinsically safe 4...20 mA sensor circuit are galvanically isolated from
both the electrode circuit and the ground and can be considered ungrounded (test voltage
500V
eff
). It is accepted that the electrode circuit can be directly connected to the ground
potential.
.book Page 12 Monday, July 21, 2014 3:08 PM