A-4.2.9.2. use of genii poly switch boards – Innotech Genesis V4 System User Manual

Page 99

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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.

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