Understanding CLR in Transformers: The Current Limiting Reactor Explained

The Current Limiting Reactor (CLR) is crucial to the bolstering of transformer applications and is an electrical system that safeguards against current surges. Despite being one of the most crucial components of the application, industry professionals easily overlook or get the wrong idea regarding their purpose and functionality. Focused on this gap, this paper aspires to examine the CLR in detail, starting from its functions to the crucial tasks it can handle, such as limiting fault currents, strengthening system reliability, and avoiding potential hardware failure. This will help engineers, aspiring electrical engineers eager to further their knowledge, and even technicians understand the complexities of how CLRs are integrated into transformer systems. In today’s world, CLRs are vital for the management of electrical systems, for understanding the core functions of modern electrical networks and reading on.

What is a Current Limiting Reactor (CLR) in a transformer?

A current-limiting reactor can be found in a transformer specifically designed with an inductive element that restrains an electrical current from reaching levels dangerous for the system. Since there is an inductive component, such a CLR reduces the value of fault currents, preventing the equipment from being damaged and ensuring stability in the system. Such functionality is notably helpful during excessive current conditions characteristic of high-capacity networks, to which the transformers and other equipment can be subjected at times.

Definition and purpose of CLR

The reactor’s construction shall take into consideration electromagnetic design concepts in addition to mechanical and thermal loads in order to ensure a reliable, functional lifespan. KCL’s goal in construction is to minimize the impact of intermittent loads and fluctuations in line current while minimizing operating energy loss. Their classifying characteristics include continuous current capability, rated voltage, and inductive reactance, which meet the needs of the electrical network. Today, they are popular with high voltage and industrial applications and are incorporated into power distribution centers.

For an ideal transformer, cooling measures reduce energy loss while simultaneously improving sensitive devices’ operational lifespan. Pmodem electrical grids, which operate at 220kv, generally need restrictors and rate-limiters to ensure excessive short circuits of 40 kA do not occur. The ideal design rotates between using a CLR with a skirting current of 20 to 10kA.

Simply put, a CLR’s functioning is more complex than merely ensuring the efficiency of a certain element type. M he power plants or electrical grids are also safeguarded during sudden electrical current surges. All in all, C T A’s operating mechanisms along the protecting contingent allow them to serve for longer periods.

How CLR controls fault current

Current limiting reactors (CLRs) mainly limit fault current by injecting circuits with inductive reactance. The additional reactance designed during fault conditions causes a hindrance to the steep growth of current, therefore limiting the amount. The reactance helps to reduce the fault current to the magnitude that the useful, protecting equipment can handle and thus reduce chances of damaging equipment such as transformers, circuit breakers, and other critical components within the network.

By way of illustration, if there is a fault current of, say, 50KA across an electrical circuit and a CLR that induces 5 ohms of reactance is fitted to the circuit, the fault current will be lowered to approximately 10-12KA subject to the system voltage. Such a large drop becomes necessary so that the circuit breakers and relays are not overworked and are kept within their thermal and mechanical capacity, and hence, stability is sustained.

Modern CLRs or current limiters are incorporated within modern protective relays for real-time monitoring and control of short circuits in the system, whereby the current limiter strategy can easily be adapted to suit the conditions within a system. These relays can analyze the state of the system and determine if there is a fault; hence, they get activated alongside a CLR for better control of the overactive current at the time. Furthermore, CLRs are designed to control the system’s voltage during faults to avert an overactive system and optimize quick restoration of the system once the fault has been cleared.

Evidence gathered from commercial applications suggests that deploying CLRs decreases the maximum fault current range between 40 and 70 percent in high-voltage power systems. Application parameters and the grid configuration are primary determinants of this efficiency. Such efficiency has made CLRs instrumental in constructing advanced substations and high-end industrial power systems.

Types of CLRs: Air core vs. Iron core

Air core CLRs are made using nonferrous substances, guaranteeing that saturation is not an issue when used and performance remains constant. Air core CLRs are also lightweight, require less maintenance, and work well under high-frequency conditions. In comparison to iron cores, however, they are larger in size and do not reduce inductance as efficiently as iron cores do.

Iron core CLRs, on the other hand, use a magnet core to maximize inductance efficiency, or as a result, they are made more compact, and their usability at low frequencies improves. However air core is much more efficient than the previous at certain applications but they do suffer from Core saturation when higher than anticipated levels of current are involved, also the require maintenance at a much slower pace than the air core. Depending on functional requirements and working conditions, both sets of devices are chosen accordingly.

How does a CLR work to limit current in transformers?

Impedance and reactance principles

Breakers, including CLRs, reduce transformer input current by raising the total impedance of the electrical circuit. CLR’s inductive reactance works by limiting the rate at which current will change, thereby controlling the amount of fault current so the transformer can be kept within moderate limits. The core energy magnetic characteristics of electrically adjustable reactors are responsible for current limiting, wherein the rate of change of the electrical current is resisted. By controlling current flow, CLRs prevent transformers from excessive loading and short circuits.

Relationship between CLR and short circuit current

The interplay between Current Limiting Reactors (CLR) and short circuit currents is paramount in ensuring the electrical systems’ reliability and safety. A CLR aims to add circuit impedance into a circuit to reduce the short circuit current (SCC) during a fault condition. By lowering the fault current magnitude, CLRs prevent overheating and mechanical violence to downstream systems such as transformers, switchgear, and circuit breakers.

For example, it can be envisaged that a system without a CLR is expected to have a maximum fault current of 50 kA, but if it had a reactor of 0.1 ohm’s reactance connected, this value could be less than 10 kA of a maximum dependent on system voltage and configuration. The lower fault current greatly reduces the chances of failures.

Power systems are growing in complexity with the incorporation of myriad substations interconnected with each other which potentially multiplies the fault levels due to the high available fault power, CLRs employed correctly have proven to be instrumental. Moreover, the proper rating of CLRs ensures that fault currents are kept within the interrupting capacity of protective devices, reducing the chances of major failures.

Current technologies are incorporating newer materials and designs to modernize CLRs to satisfy specific impedance requirements while minimizing power losses. Laboratory test results show that CLRs can prolong the life of electrical devices by minimizing wear that results from excessive fault currents, which helps reduce some of the damage that comes with excessive fault current levels. This information emphasizes their significance and affordability in controlling available fault currents while ordering the loads in protection system design.

Impact on voltage drop and load current

Current limiting reactors (CLR) have a very positive relationship with the load current and voltage drop in a power system. Their impedance, a defining attribute, limits the extent of voltage drop in both normal and fault conditions. This voltage drop is a function of the load current flowing through the reactor. For example, in systems with a CLR impedance of 0.1 to 1.0 ohms, a voltage drop of 1–5% is frequently noticed at full load, which is beneficial in managing the operating current. Such a drop makes it possible to effectively limit the fault current without compromising the system performance too much.

Moreover, CLRs aid during transient events like short circuits by stabilizing load current. They also reduce sistema damage and lower thermal stress on the devices in use by curtailing the abrupt increase in current. Some research indicates that a CLR placed at strategic locations can reduce the magnitude of the fault current to about 50%, thus protecting devices downstream and maintaining continuity within the system. This volume of current regulates voltage and suppresses fault current, which explains the engineering significance of CLRs in modern electrical networks.

What are the benefits of using CLRs in transformer systems?

Protection against excessive fault currents

Current Limiting Reactors (CLRs) are an important component used in transformer systems to aid in the reduction of excessive fault currents. As such reactors are employed, the fault current levels can be effectively limited, thereby avoiding overloading and ensuring the operational safety of the connected equipment. For example, in high-voltage transformer systems, the fault current levels could go beyond the 50 kA mark during short circuit conditions; however, using CLRs can help in limiting such high values, as per studies carried out the use of CLRs can result in a 30-60% reduction of fault levels which is also dependent on the configuration of the system and the specifications of the reactor being used.

Furthermore, as limiters of energy loss during faulty events, CLRs help maintain the thermal equilibrium of transformers hence avoiding scenarios of overheating and damage to insulation. This functional mitigation also helps reduce the stress on circuit breakers and protective relays, thereby prolonging their operational life. With advancements being made in the field of reactor design, like optimally inductance levels and compact reactors improving reliability and versatility, the deployment of CLRs is only increasing. All in all, CLRs are fundamental to the functioning of transformer systems as they provide protection and operational efficiency.

Improved power system stability

Incorporating CLRs into power networks augments the stability of electrical systems. These instruments are crucial in limiting fault current, lowering equipment stress, and maintaining the facility’s steady-state performance. Hence, they protect and ensure the durability and reliability of power distribution systems, enabling optimal and safe energy transmission.

Extended lifespan of transformers and switchgear

Using current limiting reactors (CLRs) effectively extends the lifespan of transformers and switchgear. By limiting and containing fault currents during short circuits, CLRs reduce thermal and mechanical strain on major parts of these transformers. This reduction leads to lower destruction from high fault currents, which are known to hasten the aging and deterioration of hybrid power transformers and switchgear.

Research has indicated that inhibiting fault currents can help avoid insulation failure, overheating, and distortion of devices, thus enhancing their longevity. Implementing CLR can reduce fault current by 30% to 50%, allowing a proportional reduction of failures due to heat stress if mitigated properly. This also helps improve the reliability of the current limiter and aids in preventing downtime during controlled fault induction through moderated cycles of maintenance, thereby resulting in huge savings during the life of the device.

The use of CLRs protects the equipment, provides greater efficiency, and reduces costs for businesses in today’s electricity networks with high demand and low supply.

When and where are CLRs typically installed in power systems?

Application in high voltage transformer circuits

Protection Against Transient Overvoltages

CLRs are installed to protect against transient overvoltage caused by lightning strikes or switching operations. By managing the rate of current change in transformer circuits, CLRs help decrease the voltage excess of insulation systems and avert possible flashovers.

Enhancement of Transformer Longevity

High-voltage transformer circuits fitted with CLRs can greatly reduce the exposure of transformers to high-frequency events. This aids in greatly reducing thermally induced and dielectric stresses thereby improving the operational lifespan of the transformer.

Improved Power Quality

CLRs help normalize power flow throughout the system by assisting with harmonic distortions and noise in the circuit. This improves the overall health of the electrical grid.

Reduction of Switching Surges

The switching surge may cause undesirable current spikes when operating the circuit breaker. This is where CLRs come into play as they effectively dampen these surges, protecting the transformer and equipment downstream, which would otherwise incur damage.

Fault Current Limitation

CLRs assist in limiting the fault current that arises during short circuits or when other fault conditions arise, thereby offering additional protection to the transformers and limiting the amount of damage sustained by the surrounding equipment.

Flexibility in Various Arrangements

CLRs can also be combined with transformer configurations such as delta (Δ) or wye (Y) connections, which allows for adjustments to suit the needs of the tenders in terms of design and performance.

In response to these applications, CLRs play an important part in improving the efficacy, security, and effectiveness of circuits in power systems that operate at high levels through short circuit current limiting.

Use in electrostatic precipitators.

Electrostatic precipitators (ESPs) use electrostatic charging equipment in industrial processes. They help remove particulate matter from the exhaust gasses, directly controlling air pollution. ESPs operate efficiently, using a high-voltage direct current that can reach 100k volts. Current-limiting resistors (CLRs) are crucial in this process, as they help install proper electrostatic infrastructure.

As mentioned before, high voltage and high current are used during the operation, and not only does it damage the electrostatic charger or other machinery, but it decreases the lifespan of the current ESP setup. These sudden changes can be due to a plethora of reasons, such as sudden fluctuations in voltage or even the frequent use of arcing. A CLR is able to assist in combatting all these issues, and due to its being properly designed, it ensures that all sensitive electrical current equipment is kept protected.

Moreover, resistors are helpful during the cleaning and maintenance process as they help keep the power supply constant and avoid any interruption, potentially lowering efficiency. A slight variation in designs or operating parameters and the efficiency of industrial electrostatic precipitators can reach 99%, but the general efficiency lies within 90-99%. With the proper integration of clear, it becomes easy to maintain operating safety while managing high levels of particulate loading.

Modern CLRs equipped with silicon carbide and metal-oxide composites guarantee elevated thermal consistency and exceptional durability under extreme conditions which is vital for ESP operations. Their adjusted resistance and effective system configuration enable one to minimize energy utilization while meeting strict requirements emanating from regulatory bodies.

Integration with transformer rectifiers

Combining Current Limits Resistors (CLR) with transformer rectifiers is crucial when operating rectifier systems, especially in those applications that involve high voltages. The power systems that utilize transformer rectifiers, which are devices that convert AC to direct current, need meticulous supervision on fault currents and components in order to ensure that the systems perform up to indicated limits. CLRs aid in this endeavor by regulating inrush currents upon energizing the transformer rectifiers and avoiding previous failures.

The newest transformer rectifier system suggests that installing CLRs on TMR systems might reduce the fault current by up to 50 percent for industrial purposes. This reduction prolongs the operating time of a transformer rectifier unit and its electrical systems. Besides, improved CLRs enable better voltage regulation, which aids in better current smoothing and reduces power obsoletion.

The transformative bridge converters and the transformer limiters appear complementary, enhancing the modularisation and scaling of systems. In this regard, intelligent monitoring devices could be included in current flow limiters in substation networks where anomalies in the current flow are monitored so that predictive maintenance could use them in real-time. As per the technical standards, the use of high tolerance cars and the transformer rectifiers complies with the iso/iec code for energy efficiency and safety assurance, proving their relevance in modern electric configuration.

How do CLRs differ from other current limiting devices?

Comparison with circuit breakers

Current Limiting Reactors (CLRs) and circuit breakers have uniquely different roles in electrical systems, although both are meant to help control fault currents within a system. They both have quite different working principles and use cases. With respect to controlling fault currents, CLRs supply an inductive reactance into the circuit while circuit breakers switch off the flow of current to the entire section in which the fault was detected. This basic characteristic level differentiates these components, enabling one to style CLRs as more proactive as compared to circuit breakers, which are more mitigate-focused.

Another distinction of a technical character is the response time and the response capacity of the devices. In the case of CLRs, the device is always ‘on’, meaning that it generates impedance and is able to reduce the maximum fault current by between 40% to 60%, depending on the specifications and design of the device. During the normal exercise of the electrical system, fuses carry the current to the protected circuit unless short circuit currents occur. Circuit disconnectors operate at milliseconds, which vary from 10 to 100 ms, for instance, depending on its type and system requirements.

On the structural level, CLRs can be described as passive devices due to the absence of moving parts, increasing their reliability and minimizing their maintenance requirements. In contrast, the circuit breakers constitute mechanical devices, so they have to be subjected to maintenance to ensure proper service. In addition, CLRs are also of help in system stability since they limit the extent of power surge and short circuit currents, thus minimizing the burdens on other protection appliances like circuit breakers.

Put together, these appliances provide a highly reliable organization of fault management. The IEEE Standard 242 illustrates that for high-voltage circuits that contain CLRs, circuit breakers’ rating size and cost are considerably reduced because the levels of fault currents are less. This synergy enhances system reliability and reduces the system’s downtime, therefore, the application of CLRs is effective shock absorbing equipment in today’s electrical grids.

CLRs vs. fuses for current limitation

Fuse units and circuit limiting reactors (CLRs) are both current limitation means, although they are associated with different functions in an electrical system. Dynamic devices such as CLRs are capable of lowering the fault current during a transient event, thus making the system more robust and preventing damage to the apparatus. Unlike fuses, these devices do not have to be replaced after being activated and can withstand numerous fault events.

Fuses are one-off protection switches that function by melting in the event of excessive and unwanted currents. They can be very useful owing to their low cost and ease of installation, but the fuse is, of course, an expendable device because once a fault has occurred, the device will need to be replaced, which will cause you to incur additional costs.

The choice of the two components is based on the anticipated operational conditions. Circuit-limiting reactors are the preferred option for redundancy-seeking fault tolerant systems. The fuses are better suited for low-price and low-usage applications where service and repair costs are not too much of an issue.

What factors should be considered when selecting a CLR?

Continuous current rating and fault current capacity

The continuous current rating of a Current Limiting Resistor (CLR) describes the highest current the device is able to carry without violating thermal or electrical constraints and ensures the reliability of the resistor during calms. This parameter is crucial as it ensures the resistor operates reliably under steady-state conditions. In doing so, the system helps select a CLR rated at the upper continuous current which also alleviates overheating and premature failure.

On the other hand, Fault Current rating provides the highest range of current the CLR would be able to withstand for a few seconds in the case when a fault occurs, such as a short circuit. In this instance the value is critical to ensure that the CLR absorbs enough energy during these high current events as well as retaining enough energy constant to avoid damage. A good CLR should provide a range above the maximum prospective fault levels, and the ideal fault current rating remains significantly lower than the fault levels of every system, ensuring protection from short-circuit current and failure.

As an illustration, industrial uses might call for CLRs capable of being part of the fault currents that are larger than thousands of amperes; this depends on the system voltage and what faults are anticipated. Moreover, high-performance CLRs are usually made from materials such as ceramic or metal alloys, which offer high thermal resistance and energy dissipation. Factors such as dark current, habitat temperature, air conditioning, and derating factors should also be paid attention to so as to make sure that the CLR design chosen would work to its best in its anticipated environment. A simulation may be required to ensure M. CLT ratings are within acceptable ranges for system operational and fault conditions.

Voltage drop considerations

While performing a voltage drop for a circuit, it is wise to consider it with respect to the threshold so that no losses are incurred while operating the system. In the reverse case, some instabilities can cause damage or reduce the quality of the equipment. While performing a voltage drop, it is advisable to consider conductor dimension, type, length and electrical load applied. I consider that replacing the cable with a lower gauge would help minimize voltage drop. Monitoring such situations when applying the NEC standards will guarantee compliance regulations and reliability for the respective system once current limiters are implemented. Voltage drop calculations or simulation tools may be employed to match the requirements for respective designs.

Space requirements: Dry-type vs. oil-filled CLRs

Due to their construction and cooling methods, there are notable distinctions regarding the space requirements for dry-type and oil-filled Current Limiting Reactors (CLRs). A typical urban substation or indoor installation has tight space constraints, and for that very reason, dry-type CLRs have been designed to be quite small and lightweight. The absence of oil in such systems helps mitigate fire hazards, which would have further complicated the spatial structure.

Oil-filled CLRs do not have the same compact size as the oil ones. More space is required for the auxiliary base oil equipment, including cooling radiators and oil expansion combustion tanks. Depending on the sort of safety regulations suggested, space needs to be adjusted for the possibility of oil leaks or fire. If a dry-type CLR of the same rating is placed for comparison, an oil-filled CLR will consume about 15 to 20% more space for approximately the same standard design layout set. The figure kept increasing for large-sized systems in which the cooling and size of oil-filled CLRs were directly correlated.

In the end, either of the two decisions will depend on application requirements, available space, and the priorities of the project in question. On the other hand, oil-filled CLRs are more complex in their regulation and advanced in nature, offering great thermal performance and higher durability for high-power applications. Still, they are resource-intensive and require more space in the application, while dry-type CLRs provide efficiency on the other end of the spectrum with easier maintenance. Apart from all the reasons, site constraints and space factor planning need to be prioritized primarily for making wise decisions.

Are there any drawbacks to using CLRs in transformer systems?

Impact on system efficiency

This is because any energy dissipation that a CLR can incur will ultimately drop the combined efficiency of a transformer system. From this perspective, the overall efficiency of the transformer system as a whole will be affected. Rather, to fix the issue at hand, any armature reaction that is developed is constructed using a current limiting reactor, which is said to introduce some impedance within the circuit. Although these components are imperative for controlling fault currents which can significantly improve the stability of the system, they do reduce the efficiency. Traditionally speaking, these resistive losses can be accumulated and defined as a byproduct of the flow of electrical current that is traveling through the reactor and the resistance.

It can be said that solenoid inductors have gained the attention and approval of the mainstream, as their design has a greater than 1% chance of incurring and contributing towards resistive losses; however, the selections of construction, materials along with the conditions add vast amounts of variance. Consider the scenario of an electrical grid under heavy load; the amount of energy dissipated by the CLRs seems to be pertinent as it aids in limiting electrical fault conditions. Furthermore it is able to prevent electrical damage to sensitive equipment that is situated below it.

It is certainly true for the oil-filled Core type Colii as alongside these components and structures, severe engineering processes like laminated core structures or even optimized magnetic material compositions are capable of providing and cramping efficiency losses to below an acceptable threshold. More specifically, the construction of cores with magnetic component engineers can produce hysteresis and Eddy current losses.

Through selective choices about electrical current, impedance, and material characteristics for the reactor elements, engineers are able to alleviate efficiency losses while achieving the preset fault current limit along with system safety.

Cost considerations for installation and maintenance

The installation of current limiting reactors (CLR) is heavily influenced by factors such as the size of the reactor, the type of reactor, and the installation complexity. The initial installation cost generally consists of the site preparation, purchase of necessary equipment, and the labor required. Unlike nonspecialization, dry-type current limiters tend to require more upfront investment. Ensure regular CLR maintenance and keep long-term expenses to a minimum. Long-term expenses entail the efficiency and longevity of CLRs. Routine inspection of core components alleviates the chance of excessive heating and insulation degradation, which aids in wear and tear identification. Over its service life, the system operates efficiently and reliably if the reallocation of funds for unexpected but periodic maintenance is done for smoother functionality.

Potential for transient overvoltages

Transient overvoltages refer to short-lived voltage surges following electrical switching, lightning strikes, and changes in electrical load during switch gear operations. In networks with current limiting reactors (CLR), transient over-voltages may occur when there is a fault or during the clearing of the switch. These overvoltages are predominantly due to CLRs as electrically, they possess an inductive characteristic that builds up energy, and when stability is disturbed, the stored energy gets shed into the system during a disturbance.

The CLR impedance, the network configuration, and the fault clearing time all determine the level of transient overvoltages. For example, research has shown that in bolt systems, the temporary voltage induced as a result of switching in the energy system can sometimes be powered in a range greater than 2.5 times the nominal operating level, and it has to be done with considerable care and coordination to achieve such a system design goal.

The use of surge arresters is a strategy that can directly manage high voltage by dissolving high voltage surges, whereas proper earthing ensures that the energy dissipates. Other methodologies include changing the CLR parameters, such as changing the inductance rating. Compatibility between the CLR and other devices that guard the system operations is needed to avoid the loss of protection to system operability.

Frequently Asked Questions (FAQs)

Q: What can you tell us about the Current Limiting Reactor and its role in power circuits?

A: Quite simply, a CLR is an inductive device that is used to limit the amount of current in an electrical circuit by virtue of its operation. Essentially, it works by generating a magnetic field that opposes the increase in the current, thus reducing the short-circuit current and safeguarding the equipment from damage caused by a current that is too high.

Q: In what manner are CLRs effective in inrush current limiting?

A: Inrush current limiting is achieved efficaciously by the use of CLRs because they provide a high impedance at the beginning. This impedance moves down further as the current reaches a stable point whereby, ensuring that the large shaft of current would otherwise be able to move certain pieces of electrical equipment when they are engaged in a system with high capacitance, high resistance, and low resistance.

Q: Can you differentiate between core current limiting reactors and air core current limiting reactors?

A: Core current limiting reactors are made to contain a core magnetic material which is normally made of iron and serves the purpose of enabling greater inductance in a smaller package, whereas Air core current limiting reactors do not use a core altogether and rely completely on the field produced by the winding cooled by air. For saturation concerns, Air core reactors are the preferred option as they are more reliable than their counterparts.

Q: Explain in detail how time-lagging reactors hinder further growth of a short circuit in the system.

A: The reason behind using time-lagging reactance put within the sub-circuit is to alleviate the short circuit current. The short circuit fault current would return to the breaker after passing through service and protection equipment, and its magnitude will largely be controlled by the time-lagging inductance of the reactor. The equipment is safeguarded, and low interrupting ratings are suitable for breakers.

Q: What is the importance of the current limiting reactors’ MVA rating?

A: The MVA rating of a current-limiting reactor informs us about the maximum power the fault current can induce. This denotes the highest amount of apparent power that can be provided to the reactor for maximum constant voltage. This means more current-limiting reactors for high-power systems can be employed at higher MVA levels.

Q: In what manner does a current limiting reactor impact the working of a DC rectifier?

A: In most cases, current limiting reactors are placed on the AC input of the ac input to decrease the inrush currents and harmonics at the input of the AC/DC converter. These devices help improve the input current wave shape, power factor, and protection from high inrush currents, thus greatly enhancing the performance and reliability of the DC supply.

Q: What criteria should a user follow to choose a manufacturer of current limiting reactors?

A: When choosing a manufacturer of current-limiting reactors, analyze the company’s history of constructing reactors in this and similar industries, the quality of the material used, standards compliance, the number of functionally adjustable constituents (taps for the inductance), the heat dissipation system, and warranty services. The ability of the devices to cope with the expected rated currents and short circuits in the systems must also be checked.

Reference Sources

1. Bangladesh Power System Fault Level Management – A Case Study

• Publication Year: 2019
• Authors: Md. Arifur Kabir, Md Samsul Alam, Md. Khurshedul Alam
• Summary: As the title depicts, this research analyzes fault level management in the Bangladesh power system, focusing on current limiting reactors (CLR) as a low-passive approach to the limitation of fault levels. The study observes the rapid growth of the fault current levels caused by the expansion of the power grid and the potential preventive plans that could be employed in such a situation. The methodology employed includes load flow and short circuit simulations using Digsilent PowerFactory software to study the influence of CLRs on the level of faults. It is concluded that CMR maintenance of uptime can control the fault currents to the maximum permissible limits, thereby preventing transformers and other electrical gadgets from being compromised.

2. How To Protect Zones in LVDC Using Fault Current Limiting Converter

• Authors: Jin-Su Kim, Eun-Chul Lee, Sang-Yun Yun
• Published: 2023
• Overview: A protection system for low voltage direct current (LVDC), which makes use of a fault current limiting (FCL) converter, is developed in this paper and could be regarded as a type of CLR. It is geared toward improving the overall fault performance in terms of the shielding of device status, location, and response time by actively controlling the fault current. The active FC control is achieved using a buck converter-type FCL with a phase-shift dual-active-bridge (DAB) converter. Such an arrangement or configuration will be very useful for implementing the proposed relaying approach.

3. Limiting Current and Short Circuit Protection for AC Shipboard Smart Power Distribution Module in Centralized Power System

• Authors: Zhen Yang, Jian-Zhang Feng, Bin Liu, Jian Li, Xiaotian Yin
• Publication Year: 2022
• Summary: This article strives to come forward with optimal solutions to stability and reliability issues in centralized power systems incorporated in all-electric ships. It proposes using an automated spare tamper-proof module within the automatic control system, which can provide current limiting and short circuit protection. The methodology involves detailed control strategies to distinguish load types and control surge currents. The results suggest that such systems, if integrated within electrical panels, can drastically reduce the risk of electrical faults.

4. Transformer

5. Current Limiting Protector