SYSTEM OVERVIEW

GAI-Tronics was awarded the contract to supply a PA/GA system to a newly constructed refinery in Kazakstan. A fully integrated 70KW system comprising 5 separate systems networked via LAN, it was the largest PA/GA system ever designed or supplied by GAI-Tronics.

This refinery was a grassroots project of all new construction. Key customer requirements were to provide a fully duplicated (1+1 system, see below for more detail), and certain information had to be provided in both English and Russian, specifically touchscreen access panels for user interface.

SYSTEM FUNCTIONALITY

The facility, with 70KW of total amplifier power being generated, required five separate systems that would operate independently for day-to-day communications but could be linked for intercommunication and emergency notification. In addition to networking the five cabinets, there was a system requirement for remote access to the system for programming and troubleshooting.

The customer also requested the ability to supervise the functionality and operational status of all of the cabinets to ensure maximum safety. Each of the five systems is similar; this project profile will focus on the first system to be installed.

The basic system configuration is full duplication, typically referred to as “1+1” design. Duplicated systems are found both onshore and offshore, but each is slightly different.

In onshore installations, two separate cabinets are typically located side by side. One cabinet is the primary cabinet and the other is secondary; they are functionally identical except that only one cabinet is “working”, or controlling the system, at a time. The secondary cabinet is only called into use if the first cabinet is disabled. Speakers can be wired in a single or double loop configuration. If wired in single loop, the cabinets will switch control; if wired separately, then each loop is powered independently by its own cabinet. Full duplication ensures that even if an entire cabinet is disabled in any way, the other cabinet can fulfill all system requirements and functionality will not be interrupted in any way.

At this installation, safety was further increased by the installation of one spare amplifier in each cabinet for “hot standby.” If an amplifier in the cabinet is disabled or non-functional for any reason, the “standby” amp will automatically be called into service to power the affected speaker loops. If more than one amplifier is disabled, the system will switch to use the other cabinet. In addition, each of the cabinets also has adequate space for installation of a second spare amplifier. The first system installed at this facility uses two models of access panels: one type is used by a system operator and is placed on the desktop and the second model is mounted in the cabinet. The text on both units is provided in both English and Russian.

The system also has a PA/A Network Management System (NMS) workstation. This station permits supervisory control of the system. In addition, the access panel allows remote system monitoring and, via the facility’s LAN, system configuration. When any system fault is detected, as described in the “System Monitoring” section below, an alarm is received at the NMS station. The alarms are categorized as “urgent” or “not urgent” as determined by the customer. A total of 7 speaker loops are powered from each cabinet. The speakers will be grouped into three distinct zones to accommodate different paging and announcement requirements.

SYSTEM MONITORING
This system utilizes the following modules to perform system monitoring.

8-Channel Speaker Line Monitor Module (LIM): Monitors shorts, opens, leakage to ground over 70.7V or 100V speaker lines. The LIM injects a very low current on the line to check line resistance. Any change from the baseline (established at installation) is reported.

4-Channel 35 Hz, Test Tone Generator Module / 16-Channel Tone Monitor
Module: This module works in conjunction with the Tone Monitor Module. It injects a 35 Hz tone on the audio path of each amplifier. The Test Tone Monitor, one installed in the cabinet and one installed at the end of the speaker loops, “listens” for the signal. If it is not detected, it notifies the system controller that there is a fault on the line, or in the amplifier.

SYSTEM INTERFACES
The system will interface to a PABX to provide dial-in paging for both telephones and radios. Callers from the telephone system will be able to select the zone(s) they wish to page, or may select to All-Call. Only GAI-Tronics can offer this configuration. The NOVA 2001 cabinet will also interface to the fire and gas systems, receiving one contact closure from each. The system can accommodate up to 16 inputs (only 2 will be used initially) for possible future expansion. In addition, the cabinet will be connected to four beacons; the system can accommodate up to 100 outputs for additional beacons or other auxiliary equipment requiring a
contact closure. When any alarm is sounded, the cabinet will provide a contact closure to activate the beacons.