Electrical System Design

Posted by Safety Acts | 8:03 PM | | 1 comments »

" Faulty Electrical Wiring", the most common findings of fire investigation department during fire. It's unfair for all electrical practitioners. For an efficient electrical system, brainstorming, effective planning and implementation is important.

Electric Power has a wide range of application. The world can't live without electricity. It is important in any industries from manufacturing, transportation, communication and down to the household. For large scale manufacturing, it is a must for the designer to plan and execute the reliable system without affecting the process. Any failure of the system will stop the process. Among the most common causes of  power outages are the constant tripping of the of protective devices, premature breakdown of equipment, power harmonics, low power factor, high voltage drop, low short circuit MVA from utility company, improper sizing of protective devices and conductors, and improper settings of relays and circuit breakers.

An electrical designer must come up with a reliable and economical system. It starts with the single line diagram which shows the whole electrical configuration from the service drop of the utility company, service entrance, High Voltage Switchgear, Low Voltage Switchgear, Transformers, Circuit Breakers, and distribution panel boards.

These are some key factors to be considered in designing power system:

1. SAFETY- this is always the first and important factor. Enclose all exposed conductors. All protective devices must have proper interrupting capacity to withstand high flow of short circuit currents. The conductors must have enough ampacity, the logic is that, it must have higher ampacity than the current rating of the circuit breaker. The circuit breaker must be able to cut the power during short circuits before the conductors and equipments are damage.
2. ECONOMICAL- this is another important factor though contradicts safety and reliability. It must not be evaluated on per equipment basis, rather, it must be evaluated as a whole especially in computing the return of investments.
3. EXPANDABILITY- anticipate the growth of the company. Provide an extra power capacity to allow additional installation. It is imortant to reserve in substation KVA size over predicted present loads, margin in interrupting rating of switching devices and proper selection of voltage level.
4. SIMPLICITY- the design must be as simple as posible. Most shutdowns are associated with the complexity of electrical system especially during preventive maintenance and repairs.
5. FLEXIBLITY- the electrical system must be capable of being expanded without requiring major changes in the power distribution. The use of load center type system with small substations that can be added in small units is one basic consideration in plant flexibility.
6. RELIABILITY- it is directly proportional to productivity. The designer can consider radial system, loop system, or double-ended-system  configuration and install high quality electric equipment and excellent workmanship.
7. SELECTION OF EQUIPMENT- Install equipment with adequate voltage level, current level, interrupting rating, and proper protection.
8. MAINTENANCE- design a system that will provide alternate supply to permit to be taken out during preventive maintenance without affecting the critical loads.

1 comments

  1. Anonymous // May 5, 2010 at 10:00 AM  

    nice