Fig. 28: Coaxial cable assembly
Connect pH or ORP sensors via a
coaxial cable, which relates to the
pH/ORP via mV connection type,
directly via the controller’s electrical ter‐
minal.
The controller can, depending on the
design (1 or 2 channel), measure the
pH/ORP value once or twice.
There are two connection types:
There is one connection type without potential
equalisation (unsymmetrical connection type)
or the connection type with potential equalisa‐
tion (symmetrical connection type).
When is potential equalisation
used?
Potential equalisation is used if the
pH/ORP measurement is interfered
with by disturbance potentials from the
sample media. For example disturb‐
ance potentials may arise due to elec‐
tric motors with incorrect disturbance
suppression or due to insufficient gal‐
vanic insulation of electrical conductors
etc. The potential equalisation does not
cancel this disturbance voltage, it does
however reduce its effect on the meas‐
urement. Therefore ideally the source
of the disturbance voltage should be
eliminated.
Assembly and installation
60
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