Innotech Genesis V4 System - Manual (Page 98)

Installation Instructions for Innotech Genesis Systems
Edition 011100
A-17
Figure A-16 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.
Figure A-16. Hazardous Connection Example, Circuit 2.
Switchboard or
Control Panel No. 2
Screen 1 2
Connect Screen
Screen 1 2
Connect Screen
Switchboard or
Control Panel No. 1
Screen 1 2
Connect Screen
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.
Screen 1 2
Connect Screen
Six outer links
fitted. Screen is
earthed via
Terminal 2.
A