Power Distribution in Industries . Efficient power distribution is the backbone of any industrial operation. It ensures that electricity reaches every machine, system, and process reliably and safely. Industries rely on complex power distribution systems to sustain their productivity, minimize downtime, and protect valuable equipment. This article explores the components, types, and challenges of power distribution in industries and highlights innovative trends shaping the future.
Structure of Power Distribution in Industries
In an industrial electric power system, electric power is supplied from either private utilities or public utilities, or both. The supplied voltage is in the range of 11KV, 33KV, 66KV or 132KV. These high voltages are stepped down to a low voltage using step-down transformers.
The voltages in the range of 440 volts or below are called as low tension systems. This stepped voltage is further supplied to various panels and equipments through a switchgear arrangement that consisting of electrical switches, circuit breakers, fuses, protection equipment, metering boards, etc.
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The figure below shows a schematic diagram of the power distribution. This model scheme is mostly employed for large and medium scale industries. In some cases, sub-LT panels are not found; instead power is supplied directly from LT panels to SDBs depending upon the size of distribution area where the number of units (or sections) to be supplied is the major consideration.
In the above figure, the elements in this power distribution model included LT panel, sub-LT panel, SDB (sub-distribution board), PDB (power distribution board) and LDB (lighting distribution board).
Various transformers supply is given to the LT panels, which acts as a main switching system for entire power distribution scheme and carries the total load demand. We will discuss the elements inside of the LT panels in brief later in this article. The output feeders of the LT panel are connected to sub-LT panels which are placed for a group of loads over a given section to supply the demand.
The sub-LT panel incomer is applied at SDB which are placed for supplying the power to loads that consists of a group of machineries such as electrical furnaces, hoists, etc. (that are connected to various PDBs).
PDBs acts like an actual power connection of load to source where individual machinery is connected directly to the supply. And part of the power from PDB is supplied to LDBs where it supplies the power to lighting equipment such as street lights lighting in the working area, plug boards etc.
All the panels in the distribution system are ground with a proper grounding & earthing to protect the appliances as well as operating personnel.
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Importance of Power Distribution
Power distribution is critical in industrial settings for several reasons:
- Productivity: Proper power allocation ensures machines operate without interruptions.
- Efficiency: Reducing energy waste directly impacts profitability.
- Safety: Well-designed systems protect equipment and personnel from electrical hazards.
Without an optimized power distribution network, industries face risks like equipment failure, downtime, and even catastrophic damage.
Low Tension (LT) Panel
The switchgear arrangement on each distribution side is housed in metal-enclosed structures called as LT (low tension) panels. These LT panels are responsible for distributing the power to various sub LT panels by receiving it from the transformer. These are rated for 430 V, 3-phase, 50Hz three or four wire system.
It is a floor mounted free standing unit and it is totally closed and extensible type. Its design includes all provisions for safety of operation as well as for maintenance personnel.
The internal connection for the LT panel is shown in figure below.
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Components of Industrial Power Distribution Systems
Industrial power distribution relies on several key components to deliver electricity efficiently:
Transformers
Transformers play a vital role in stepping up or stepping down voltage to match industrial needs. Common types include:
- Step-Up Transformers: Increase voltage for long-distance transmission.
- Step-Down Transformers: Decrease voltage for machinery and operational use.
- Specialized Transformers: Serve specific requirements like isolating circuits or managing harmonics.
Switchgear
Switchgear ensures safe operation by controlling and protecting electrical circuits. Types include:
- Air-Insulated Switchgear (AIS): Suitable for moderate voltage systems.
- Gas-Insulated Switchgear (GIS): Preferred for compact and high-voltage environments.
Circuit Breakers
These devices prevent overloads and short circuits, ensuring the safety of industrial systems. Types include:
- Miniature Circuit Breakers (MCBs) for low-voltage systems.
- Air Circuit Breakers (ACBs) for higher capacity protection.
Distribution Panels
Distribution panels centralize control, distribute power, and include built-in safety mechanisms to safeguard operations.
Power Distribution in Industries
Air Circuit Breaker (ACB)
It makes or breaks the circuit either manually or remotely controlled during normal operating condition and break the circuit during fault condition automatically. These can be 3/4 pole type with a rating decided by the load current (or breaking capacity) and can be either drawn out or fixed type.
ACBs (Air Circuit Breaker) consist of necessary bus bars to connect the terminals with bolted type neutral links. These are provided with microprocessor systems to enable protection systems like overload, earth fault and short circuits. ACB also gives the necessary indication and metering requirements with the use of CTs, lamps, ammeter, voltmeters, etc.
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Bus Bar and Connections
Bus bars are made with high conductivity copper (in some cases, aluminum bus bars are used to reduce the cost). LT panel consists of a system of main horizontal bus bars and auxiliary vertical bus bars in bus bar alleys on which panel could be arranged with front access to connect cables.
The outgoing cables are connected to the bus bars either as a solid or flexible connection depends on the panel manufacturer. All bus bars are suitably insulated / sleeved in approved manner.
Bus bars collect the supply from transformer terminals and supply it to the various elements in the panel such as ACBs, capacitor bank switch gear, and other connected loads. The bus bars can be run at either top or bottom, or both sides of the panel, but mostly top side bus bars takes the transformer supply while bottom side bus bars take the supply from DG (Diesel Generator) set.
Bus Coupler
It couples one bus bar with other bus bar of different source (but the rating should be same) without creating any arcs or interruption to the supply system. In case of maintenance of other circuit breakers on the same panel this bus coupler diverts the supply source to the other. It is also a switchgear arrangement with ACB and provided with interlocking facility.
Capacitor Bank
It is a separate panel that consisting of bus bars, MCCBs, tuned reactors, capacitor units, contactors, metering equipment, and cables. It is also called as automatic power factor correction panel (APFC). This panel is connected to the LT panel with ACBs and other switchgear arrangements through cables.
The capacitors and reactors are of an indoor type with air cooled units. The capacitor banks are connected across the supply to improve the power factor o f the system. Capacitors are switched automatically (through programmable devices) or manually (by switches) depending on the amount of reactive power to be compensated.
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Metering and indication
Voltmeters, ammeter and power factor meters in LT panel indicate various parameters and these are protected with MCBs. On all LT panels, indicating lamps (mostly LED lamps) are provided for each phase for indicating live or fault condition. Start and stop push buttons also provided on metering panel to give input commands such as turn ON supply and emergency stop.
Sub-LT Panels
These panels are similar to the LT panels, however rating of these panels is somewhat less than LT panels and also these are placed in a particular section of an industry (such as assembling section or dispatching section) instead near the transformer as in case of LT panel. These are acts as mains for various SDBs, because these panels distribute the power to the SDBs by receiving it from LT panels.
The internal circuitry is same as that of LT panel such as bus bars, capacitor bank connections, ACBs, metering panels (bus couplers may not be included in most cases).
These panels also consist of utilities bus bar chamber as well as DG (diesel generator) set bus bar chamber so that some loads (SDBs) can be switched to DG supply during less amount of power supplied from utilities. However, most cases DG chamber may not be included in sub-LT panels instead it is placed in LT panel itself. Sub LT panels also include capacitor banks or APFC unit to improve the power factor.
Lighting Distribution Boards (LDBs)
These are the final switch boards (In electrical wiring & installation) and are located at small electrical loads switching areas including lighting, air conditioners, small motors switching, distribution boards for plugging portable devices like blowers, etc. We can also observe these LDBs in our homes and offices as they are employed in low switching operations.
LDBs consist of various MCBs where each MCB acts as a switch for individual loads (some cases two or more lights can be connected to single MCB). These MCBs protects the loads against overload as well as short circuit conditions. These MCBs are mounted or fixed to the metal racks. These boards receive the power from PDBs and then supplies to the lighting loads. Mostly these are of wall mounted type boards.
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Sub-Distribution Boards
These are available in standardized and customized designs from various manufacturers. SDBs consist of bus bars (copper or aluminum) that receive power supply from either sub-LT panels or main LT panels and then distribute it to various heavy rated machineries (such as furnaces, chillers, water pumps, ovens, etc.) and PDBs (power distribution boards).
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It receives the power (i.e., incomer) through ACB or MCCB and distributes through outgoing MCCBs or SDFUs (Switch-Disconnect-Fuses). The SDFUs consists of switches in series with fuse links (high breaking capacity HRC fuses) with mechanical structure for manual operation. These switching units are used for load switching, isolation and short circuit protection.
Some SDBs also consists of capacitor banks especially that (SDBs) are provided to supply heavy inductive loads in order to improve the power factor. SDBs use bus bars to enable connection of all the SDFUs and other devices inside of it through the bus bar chamber, also enables the outgoing connections though high capacity cables in the cable chamber.
Each load switching compartment is provided with permanent identification labels, indication lights and metering equipment (if necessary). The figure below shows the schematic diagram of an SDB.
Types of Power Distribution Systems
Industrial power distribution systems vary by voltage levels to suit specific needs.
High Voltage Systems
Used in large-scale industries, these systems deliver power to energy-intensive machinery over long distances.
Medium Voltage Systems
Medium voltage systems balance cost and capacity, serving factories and industrial plants effectively.
Low Voltage Systems
Ideal for small industries and workshops, these systems are cost-efficient and simpler to manage.
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Power Quality in Industries
Power quality is crucial for seamless industrial operations. Poor quality can lead to equipment damage, inefficiencies, and safety risks.
Voltage Stability
Voltage fluctuations affect sensitive machinery, causing malfunctions or downtime. Stabilizers and voltage regulators help maintain balance.
Harmonic Distortion
Electrical harmonics, caused by non-linear loads, lead to inefficiency and overheating. Harmonic filters and corrective techniques are used to mitigate these issues.
Surge Protection
Sudden power surges can damage equipment. Surge protectors shield systems from such risks, reducing downtime.
Energy Management in Power Distribution
Efficient energy management ensures optimal power usage, saving costs and resources.
Smart Grids in Industries
Smart grids enable real-time monitoring and control, enhancing flexibility and resilience.
Load Balancing Techniques
Load balancing distributes electrical demand evenly, preventing overloads and optimizing power usage.
Power Distribution in Industries
Safety Considerations
Safety is a non-negotiable aspect of power distribution. This includes:
- Compliance: Adhering to electrical standards and regulations.
- Training: Educating staff on proper equipment handling.
- Maintenance: Regular inspections to prevent accidents and downtime.
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FAQs
1. What is industrial power distribution?
Industrial power distribution refers to the systems and components used to deliver electricity within industrial facilities, ensuring efficient and safe power usage.
2. Why is power quality important in industries?
High power quality prevents equipment damage, minimizes downtime, and ensures smooth operations.
3. What are the main types of power distribution systems?
They include high voltage, medium voltage, and low voltage systems, each catering to different operational needs.
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