The distribution system comprises of the primary system and the secondary system. The primary system includes circuits at voltages somewhat higher than general utilization levels and handles higher blocks of electrical energy than the average low voltage consumers. Power can be tapped from the primary system only at the substation and not in the route of the line connecting primary and secondary distributions substations.

Almost all primary circuits are three phase. On the other hand, secondary system supplies power to small consumers (domestic, small scale business and industries) at much lower voltage level and the power is tapped all along the route of distributors which carry power from the secondary distribution substation to consumers. At the secondary distribution level, the consumers are supplied either with three phase supply 415V or with single phase 240V. Secondary distribution system is the link in the chain between the generating station and individual consumers.

A low voltage (LV) distribution system in Malaysia is from 11/0.415 KV substation. Feeder pillar connected to the LV side of a substation transformer is the main part of the low voltage distribution system. At the feeder pillar various bus bar are available to supply power to consumer either by overhead or underground line. Fuse is connected to each phase at all bus bar for protection. Fuse protected system on low voltage depends entirely on human intervention because when the fuse blew can only be manually replaced.


Low voltage substation transformer


Low voltage substation feeder pillar