Generally power is produced by power generating stations. The power distribution system shall be designed to cater for the Maximum Demand with peak design capacity, at maximum ambient conditions and an additional spare capacity of minimum of 25% to cater future loads, the distributed systems shall be designed for effective and safe control of electrical power supplies to plant under all operating conditions.
Types of power distribution
- Single Radial systems
- Double Radial systems
- Triple Radial systems
- Ring feed systems
Single Radial systems:
Single radial system should be used to provide power to non-essential electrical loads or those loads, for which a lower availability can be accepted by asset group. Each component single radial circuit shall be capable of supplying Maximum Demand associated and a minimum of 25% spare capacity to cater for future addition, unless otherwise specified.
Double Radial systems:
load centre serving plant necessary for maintaining production, export operations and other major Facilities shall be provided with dual feeders at each voltage levels. each feeder shall be sized for the plant’s Maximum Demand plus a minimum of 25% spare capacity to cater for future additions, unless otherwise specified in the project document.The system shall include the provision of duplicate feeder cables, transformers and incommer circuit breakers so arranged that maintenance can be carried out without interruption to the plant operation.
Each section of the busbar shall be interconnected with bus section circuit breaker. The system is normally run with the bus-section breakers closed, unless otherwise specified in the project document. Typical application of double radial system includes, but not limited to:
(i) Gathering Centres,
(ii) Booster Stations,
(iii) Other major operating Facilities,
Triple Radial System
Triple radial systems shall be provided where the power requirement is relatively large and cannot be managed with dual radial feeders, each circuit of triple radial systems shall be capable of providing at least 50% of the total design load (Maximum Demand + 25% spare capacity), the busbar shall be split into at least three sections with two bus section breaker. This will alow for the loss of any one of the three circuit feeders, leaving the two healthy circuits still capable of providing the required load. It shall be normally operated with all Three (3) circuits in parallel. Typical applications of triple radial system includes, but not limited to:
(i) Gathering Centres,
(ii) Booster Stations,
(iii) Other major operating facilities.
Ring Feed Systems
Power may be distributed from a Bulk Intake (Primary) or Area substation to a number of subsidiary load centres by using two primary cable feeders connected in a ring emerging from the source busbar and controlled by circuit breakers, Ring type distribution systems should be used as a cost effective solution for supplying electrical loads distributed over a large area, Open ring system is normally used in indutrial for all application. Where the ring is required to be kept closed to improve the reliability, necessary protection and interlocks shall be provided to prevent back feeding.
In order that a faulty section of the primary ring may be disconnected and repaired without power loss during the whole of the repair period, the ring shall include isolating means at every load centre (substation). Typical application of open ring system includes, but not limited to
- housing
- water wells
- oil wells
- tank farms
