Hydrological Services Pty Ltd
Data Logger Model ML1-420
©
Copyright
ML1-420 100-37
Issue 1.00 6 Apr, 2011
Appendix C. Surge Protection
The ML1-420 has a limited amount of surge protection on the inputs and outputs. If the
equipment is installed in a lightning prone area we recommend installing additional surge
protection on cables entering the ML1-420 from outside the housing cabinet.
Different suppression is required, depending upon the voltage to be protected.
Figure C.1 and Figure C.2 show suggested methods of protecting equipment against
transients. The transient suppressors and the metal cabinets should also be connected to a
solid earth at the site.
(NOTE: HS warranty does not cover equipment damaged by surges or transients !)
Fig C.1 “Protection when transducer is located remotely”
“Critec UTB15
Transient Barrier”
+
+
-
Earth
+
12V Battery
“Keep Wiring
separated”
Equip
Side
Line
Side
ML1-420
Metal Cabinet
PS98i
Transducer
4-20 + => White = (V+)
4-20 - => Blue = pressure signal
Shield = Ground
4-20 +
4-20 -
If transducer cable is run a
long distance, then put it
in a galvanised pipe and
earth at both ends to
protect against transients.
Earth
Sintered
Filter