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the bottom of the window that provide clearance for routing cell cables and any
tubing out of the enclosure. If required, cables and tubing may be routed through
the back panel by drilling small holes in the panel. Any such drilled holes should
have a diameter no greater than 13.0 mm (0.5 in).
4.5
Proper Grounding
To avoid issues with signal noise when making electrochemical measurements, it
is important to properly ground all metal objects near an electrochemical cell to
the earth ground. This generally includes the metal chassis of the instrumentation
(potentiostat and rotator), the clamps and supports used to physically secure the
electrochemical cell, and any peripheral equipment (heaters, stirrers, etc.) used
in conjunction with the measurement.
4.5.1
Terminology
Note:
When working with electrochemical equipment, it is important to
understand the meanings of terms such as “earth ground”, “chassis
terminal”,
and
“DC common”
.
An
earth ground
connection is available in most modern
laboratories via the “third prong” on the power receptacle for the
local power system. The power system infrastructure for a
laboratory building usually has a long metal probe buried in the
earth, and the “third prong” in the building wiring is connected to
this earth connection.
A
chassis terminal
is a connection to the metal chassis surrounding
an instrument. Depending upon how the instrument is connected
to other experimental apparatus, a chassis terminal may or may
not be connected to the earth ground.
In the context of an electrochemical experiment involving a rotating electrode,
the
DC Common
(also known as the
signal ground
or
signal common
) is the zero
voltage reference point used by the signal measurement (or waveform
generation) circuitry in the potentiostat and the rotation control circuitry in the
rotator. The DC common may or may not be connected to the earth ground
depending upon how the experimental apparatus is arranged and depending
upon the internal circuitry of the potentiostat.
4.5.2
The Earth Ground Connection
On the front panel of the MSR rotator control unit, there is an earth ground
connection (see Figure 4.12). This connection point is in contact with the earth
ground via the “third prong” of the power cord. As long as the power system in
Summary of Contents for MSR 636A
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