Innotech Genesis V4 System - Manual (Page 64)

Installation Instructions for Innotech Genesis Systems
Edition 011100 4-9
WARNING
DIGITAL OUTPUTS ARE CONTROLLED BY RELAYS WITHIN
THE ASSOCIATED GENESIS UNIT.
THESE RELAYS ARE
CONNECTED TO EXTERNAL CIRCUITS THAT CAN CONTAIN
UP TO 240Vac. PROCEDURES IN THIS MANUAL REQUIRE
CHECKING THESE CIRCUITS WITH POWER APPLIED. TO
AVOID DEATH OR SERIOUS INJURY BY ELECTRICAL SHOCK,
USE
EXTREME CAUTION WHEN WORKING WITH
ENERGISED CIRCUITS AND FOLLOW PRECAUTIONS IN THIS
MANUAL. CHECKS ARE TO BE PERFORMED ONLY BY
QUALIFIED, LICENSED ELECTRICIANS WHO ARE FAMILIAR
WITH
LOCAL SAFETY PROCEDURES. UNDER NO
CIRCUMSTANCES SHOULD ANYONE OTHER THAN A
QUALIFIED ELECTRICIAN PERFORM THESE CHECKS.
4-1.2.3. Checking Digital Output Wiring. Digital outputs of the various units are
interfaced through relays, each having single-pole changeover contacts.
The Genesis II Digital Controllers and the Digital Output Module (DOM) LEMs are
provided with both Normally Open (NO) and Normally Closed (NC) contacts in each
digital output channel. The following units contain only NO digital output contacts:
Genesis I Digital Controller
GENII MPC Mid Points Controller
GENII MP REM Multipoints Module
GENII DO REM Relay Output Module
Relay contacts in all units with digital outputs are rated at 240Vac, 2A. For this reason, the
presence of lethal voltages at the relay contacts should be anticipated. Even though good
wiring practice is to use lower voltage pilot relays when controlling higher voltage
equipment, this practice can not be guaranteed and it is possible that the relay contacts will
carry dangerous voltages. For this reason, it is important that only a qualified electrician,
familiar with safety practices, check the digital output wiring.
Before checking the digital output circuits, it is important to ensure that there are no short
circuits in the external wiring which could cause the contact current to exceed 2A. Current
in excess of 2A through the relay contacts will result in permanent damage to the unit.
Following is a general description of the process for safely checking digital output circuits.
Specific procedures for checking the wiring are provided toward the end of this paragraph
(see Figure 4-4).
With power applied to the digital output circuits, but not to the Genesis unit, the output
circuits are checked for operation. Devices connected between the NC and C terminals
should be operating and devices connected to the NO and C terminals should be de-
energised. If the operational status cannot be determined by observation (indicator lamp
on/off, fan running/not running, etc.) a voltmeter is placed across the device to determine
whether or not it is energised.