14
6.2
ELECTRICAL GROUNDING / PROTECTION
An M6 earth bolt is provided, this is attached to the earth stud. The Earth Stud is indicated
by the Earth symbol embossed in the casing located at the front of the case, between the
two front lower bracket mounting holes.
Destructive over volt transients can occur in many ways; e.g., lightning induced transients,
AC power line transients and EMI/RFI electromagnetic noise. The power/control subsystem
of the sensor contains transient surge-arrestors on all power and signal lines as a standard
feature. EMI filters are present on the power and data lines entering the power/control
subsystem.
The following notes are intended to provide some guidance in the design and construction
of an electrical grounding system.
(1) Ground Rod: An 2.5m ground rod should be used to make contact with moist soil during
even the driest periods.
(2) 13mm
2
solid copper wire should be used to connect the instrument (and thus the
transient voltage suppressers) to the Ground Rod. Use the shortest and most direct paths to
the ground. Simply connect the wire between the Earth Stud provided on the front of the
lower mounting flange of the instrument and the Ground Rod
(3) System Interconnections: Eliminate all isolated ground loops. The shield of the signal
output cable, for example, should be attached only at one end of the cable and left floating
at the other end. Preferably, it should be attached to ground at the sensor end of the signal
cable.
(4) Connections: Use tight, corrosion-proof bare metal connections throughout the
grounding system.
Please ensure that earth safety regulations applicable to your area are followed.
This sensor
MUST BE EARTHED.
Failure to install a suitable earth may result in
inaccurate readings and / or damage to the sensor. Failure to install an earth when using
mains voltages on the relays will make the sensor potentially unsafe.
Earth Stud
