Innotech Genesis II Digital Controller (v5) - Manual (Page 118)

Genesis II Installation Instructions
Page 118 © Mass Electronics Pty Ltd 2010 Edition 2.0 dated 06/12/2013
Figure 5-16 below shows a wiring arrangement that is slightly better. The earthing point for
the screen is at the first Digital Controller in a group located together and supplied from one
switchboard. It gives better protection to the greater number of Digital Controllers. This
arrangement does not remove the hazard that the screen voltage at point A in the figure is not at the
earth voltage of that Digital Controller. Nor does it remove the possibility of damage to the RS485 ICs
if the voltage difference exceeds the voltage ratings of the IC.
If the three Digital Controllers in Control Panel No. 2 are solidly bonded together and to earth, then it
is possible that only the RS485 IC in the Digital Controller in Control Panel No. 1 will be damaged.
Switchboard or
Control Panel No. 2
Screen 1 2
Connect Screen
89 90 91 92 93
Screen 1 2
Connect Screen
89 90 91 92 93
Switchboard or
Control Panel No. 1
Screen 1 2
Connect Screen
89 90 91 92 93
Only four outer
links fitted.
Screen is not
earthed.
Only four outer
links fitted.
Screen is not
earthed.
Only four outer
links fitted.
Screen is not
earthed.
89 90 91 92 93
Screen 1 2
Connect Screen
Six outer links
fitted. Screen is
earthed via
Terminal 2.
A
D
ANGER
OUS EAR
TH C
ONNEC
TION!
NO
T
TO BE USED!
Figure 5-16: Hazardous Connection Example, Circuit 2