Chapter 4 Installation and Wiring
4-11
4.2.3
Grounding
This section describes the precautions for grounding the ST unit.
• When supplying power to the ST unit, be sure to separate the
input/output and power lines, as shown. [diagram (a)]
• If exclusive grounding is not possible, use a common
grounding point. [diagram (b)] A D-type grounding or equiva-
lent should be used for the grounding point.
Do not use common grounding, since it can lead to an accident or machine breakdown.
• Check that the grounding
resistance is 100
Ω
or less.
• FG and SG terminals are internally
connected in the ST. When
connecting an external device to
the ST using the SG terminal, be
sure to check that no short-circuit
loop is created when you setup the
system.
• The grounding wire should have a
cross sectional area greater than
2mm
2
. Create the grounding point
as close to the ST unit as possible,
and make the wire as short as
possible. When using a long
grounding wire, replace the thin
wire with a thicker wire, and place it
in a duct.
•
If the equipment does not function
properly when grounded, disconnect the
ground wire from the FG terminal.
(a) Exclusive Grounding (BEST)
(b) Exclusive Grounding (OK)
(C) Common Grounding (Not OK)
ST
ST
Other
Equipment
ST
Other
Equipment
Other
Equipment
