Specific Electrical Design Requirements for Commercial Buildings – Part One

In the previous Topic “General Electrical Design Requirements for Commercial Building"
I explain the types of Commercial building and the general outlines of electrical requirements for these buildings.

Commercial buildings 

Today, I will explain in detail the specific Electrical Requirements for Commercial Buildings which must be known for any engineer wants to learn or practice the electrical design engineering.
The following aspects should be taken into consideration when designing electric power distribution systems for Commercial buildings: 

  • Simplification of operational management by transparent, simple power system structures.
  • Low costs for power losses, e.g. by medium-voltage-side power transmission to the load centers.
  • High reliability of supply and operational safety of the installations even in the event of individual equipment failures (redundant supply, selectivity of the power system protection, and high availability).
  • Easy adaptation to changing load and operational conditions.
  • Low operating costs thanks to maintenance-friendly equipment.
  • Sufficient transmission capacity of equipment during normal operation and also in the event of a fault, taking future expansions into account.
  • Good quality of the power supply, i.e. few voltage changes due to load fluctuations with sufficient voltage symmetry and few harmonic distortions in the voltage.
  • Compliance with applicable standards and project related stipulations for special installations.

It is known for all designers that the general factors affecting the network configuration selection and design in commercial buildings are as follows:

  1. The respective supply task.
  2. The building dimensions.
  3. The number of stories above / below ground.
  4. The building use.
  5. The building equipment and power density.

any designer wants to optimize his design by completely satisfying the individual needs of the building users, and in case of Commercial building design , these individual needs will be generally as follows:

  1. Low investment.
  2. Straightforward network configuration.
  3. High reliability and quality of supply.
  4. Low power losses.
  5. Favorable and flexible expansion options.
  6. Low electromagnetic interference.

And any network configuration must be characterized by the following:

  • Number of feeder points.
  • Type of meshing and size of the power outage reserve.
  • Size and type of power sources.

Types of LV networks configurations:

The stated characteristics in above divide network configurations into two main types as follows:
  1. Radial networks.
  2. Ring / Mesh networks.

1- Radial networks:
Radial Network

Low-voltage-side power distribution within buildings is preferably designed in a radial topology and generally the radial networks have the following advantages:
  • Easy monitoring of the power system.
  • Fast fault localization.
  • Easy and clear power system protection.
  • Easy operation.

2- Ring / Mesh networks
Ring / Mesh Network

Operating a meshed low-voltage system with distributed transformer feed-in locations places high requirements on the design and operation of the power system. For this reason, ring-type systems in combination with high-current busbar trunking systems are preferred today, in particular in highly consumptive industrial processes. The advantage of a ring-type system with distributed transformer feed-in locations in the load centers as compared to central feed-in with a radial network will be as follows:
  • The reliable and flexible supply of power consumers, 
  • The better voltage maintenance, in particular in case of load changes, 
  • Lower power losses. 

In the Basic Electrical design course EE-2 – Level I, I will explain in detail the using of radial and ring networks concepts in the following stages (see fig.1):
  • Configurations of LV side power distribution within buildings 
  • Connection to the upstream Networks (MV side power distribution) 
  • Configurations of MV side power distribution
In this course , EE-1: Beginners' Electrical design course
 , We will study the famous power system architectures for the commercial buildings which can be counted as references can be modified/ extended to meet specific customer project requirements.

These famous power system architectures for the commercial buildings include:

  • Low building, type 1: One supply section.
  • Low building, type 2: Two supply sections.
  • High-rise building, type 1: Central power supply, cables.
  • High-rise building, type 2: Central power supply, busbars.
  • High-rise building, type 3: Transformers at remote location.
  • High-rise building, type 4: Distributed supply, cables.
  • High-rise building, type 5: Distributed power supply, busbars.

In the next topic, I will begin to explain these famous power system architectures for the commercial buildings. So, please keep following.

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