Fig. 24: Coaxial cable construction
Connect pH or ORP sensors using a
coaxial line (this relates to pH/ORP
connection via mV) directly via the
controller's electrical terminal.
The controller can measure the pH/
ORP value once or twice, depending
on the design (1- or 2-channel) .
There are two types of connection:
There is a connection without potential
equalisation (unsymmetrical connection
type) or a connection with potential equali‐
sation (symmetrical connection type).
When is potential equalisation
used?
Potential equalisation is used if the
pH/ORP measurement is interfered
with by disturbance potential from the
measurement media. For example
disturbance potential can be caused
by electric motors with incorrect inter‐
ference suppression or due to insuffi‐
cient galvanic insulation of electrical
conductors etc. Potential equalisation
does not remove this disturbance
voltage, however it does reduce its
effect on the measurement. Therefore
ideally remove the source of the dis‐
turbance potential.
Assembly and installation
47
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