Innotech Genesis V4 System - Manual (Page 99)

Installation Instructions for Innotech Genesis Systems
Edition 011100
A-18
A-4.2.9.2. Use of GENII POLY SWITCH Boards. The GENII Poly Switch
Boards provide some protection from over-voltage and voltage spikes. To achieve the
maximum benefit, Poly Switches should be fitted to all Digital Controllers in a network.
Fitting Poly Switches to all Digital Controllers results in the screen(s) being unearthed
because the Poly Switches do not link the screen Terminal 91 to the Common and
Terminal 2. An external earth must be fitted to Terminal 91 of the Digital Controller
where the screens are to be earthed.
When the Digital Controllers are supplied from two different switchboards (Figure A-
17), the hazardous situation is still a possibility in the event of a fault. The Poly
Switches may protect the RS485 ICs providing that the voltage differences are not
excessive. Fitting the screen earth at the single Digital Controller is not the preferred
location.
Figure A-17. Use of GENII Poly Switch Boards, Circuit 1.
Connect Screen
Screen 1 2
Connect Screen
Screen 1 2
Connect Screen
Poly-Switch
board only links
data. Screen
isolated.
Only four outer
links fitted.
Screen is not
earthed.
Screen 1 2
Switchboard or
Control Panel No. 2
Switchboard or
Control Panel No. 1
Connect Screen
Poly-Switch
board only links
data. Screen
isolated.
Screen 1 2
Poly-Switch
board only links
data. Screen
isolated.