Electricity Asset Management Plan 2019-2029
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Vector Limited://
Figure 4-40 Age Profile for RTUs
Condition and Health Our 1980s to late 1990s RTU fleet is reaching end of life and is not technically supported anymore with no spares available from suppliers. Failure of RTUs in load control installations results in loss of load control and loss of control of streetlights. Failure of other RTUs result in loss of visibility of substation plant and loss of remote control with commensurate health and safety risks as well as a risk to the reliability of the system. Strategy Vector has a standardised and modular design for substation LAN systems that is described in design standard ESE802, Automation and Control in Zone Substations and the EDE8004 suite of design drawings. These modular designs are used for zone substation refurbishments and new zone substations. To ensure continued control and visibility of substations and continued load control there is a programme to replace technically unsupported RTUs over a number of years. The new units will be suitable for the transfer of large volumes of data and will also be suitable for our new initiatives that will include on-line transformer gas analysis, cable partial discharge, temperature sensing and will offer optimal scalability for the number of interfaces and signals required for the future energy network. The Asset Strategy for zone substation automation systems is detailed in Vector’s asset strategy EAA805 Automation Systems. The proper functioning of protection systems and the reinstatement of electricity in the zone substation after a fault are reliant on able and trustworthy DC systems. The DC system is continuously charged as a back-up power supply in the event of an AC outage on site. DC auxiliary systems provide supply to the protection, automation, communication, control and metering systems, including power supply to the primary equipment motor driven mechanisms in zone substations. In our zone substations we have standardised on 110 V DC systems but utilise 30 V DC in distribution substation sites. The battery chargers simultaneously supply 110 V DC to the zone substation protection and control systems and float charging to the 110 V DC station battery bank(s), (aka ‘strings’). For an alternating current (AC) failure event of the battery charger the battery banks provide an unswitched 110 V DC supply to the protection and control systems, i.e. as an uninterruptable DC supply. Battery monitoring is essential to ensure battery systems continue to have the capacity to operate equipment during a supply outage and to enable restoration of supply once any contingency has been rectified. Battery voltages are alarmed to the SCADA system to alert the EOC to low battery voltage. 4.7.5 DC SUPPLIES Overview
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