PFC Power Factor Correct system

How Do Power Factor Correction Capacitors Work?

A power factor correction capacitor (PFC capacitor) is a type of equipment that can help to improve the power factor of an electrical circuit.  

For example, if there’s a lagging current within the circuit, it will require additional power from the supply. This is also the case if there’s a leading current within the circuit, where the voltage waveform is slightly behind the current waveform. 

It is possible to balance the inductive load with the capacitive load which can then cancel out the extra power requirement from the supply.

A PFC capacitor will provide a leading current to help bring the measure closer to unity (power factor of 1). This is the point at which the voltage waveform and the current waveform are balanced.

The closer the measure is to unity, then the less power that is drawn from the supply. This reduces demand, which means less electrical generation is required.

An electrical circuit is a circular path that allows electricity to flow. This network is closed, enabling a return path for the current. The process of improving the power factor of an electrical circuit is called power factor correction (PFC). 

One of the ways PFC is achieved is by adding a capacitor to a circuit alongside your switchgear. The capacitor stores energy in an electric field which can help to improve the efficiency of your electrical systems which in turn will reduce electricity costs.

What are the main components of PFC capacitors? 

The main components that makeup PFC capacitors include the following: 

  • MKP capacitors
  • Fuse-gear
  • Switchgear
  • Contactors
  • Reactive power controller

Where there are fast-changing loads (usually welding loads) the contactors may be replaced with thyristor switches and the controller changed to one that can react quicker. This reduces the total kVA (kiloVolt Amperes) that is required, thus reducing the high transient-like peak currents that the transformer recognises.

There can be unwanted frequencies in an electrical circuit. The voltages that are in multiples of the power frequency are called harmonics. When harmonic currents are high, in-line reactors will be fitted to prevent any resonance and amplification of these currents.

In systems that have a low power factor, or that have other issues to do with the power quality, an Active Harmonic Filter will be the best option. The filter can be programmed to attenuate harmonics in addition to providing power factor correction. This is an increasingly popular way to provide PFC as the unit can be reappropriated, or added, in order to perform other power quality tasks.

Where in the machine would PFC capacitors be? And what exactly does it do? 

PFC capacitors are either fitted locally to the equipment that has a low power factor, such as a DOL (direct online) motor, or, generally, to the main board of the system. This is often called bulk correction. 

Capacitors are installed to an electrical circuit that have a poor power factor. They are added to the electrical circuit to ensure that the kVAR (kiloVolt Amps Reactive), which is required by the load, is supplied locally rather than by the main supply. This reduces the current drawn throughout the grid. By counteracting the current, the PFC capacitors will cut wastage which in turn will reduce electricity bills.

How are PFC capacitors fitted?

The bulk correction is split into discrete stages. They are brought in and out of the circuit via contactors controlled by a reactive power relay. 

The power relay monitors the power factor of the system and switches the stages required to meet the target power factor.

A reactive power controller is required to monitor the load by maintaining the reactive power output. To prevent surges associated with capacitor switching, soft-switching contactors are utilised with in-rush attenuating devices. 

The relay has a number of features that prevent capacitors from switching whilst still being charged.

The capacitors are fitted in parallel with the motor or circuits.  The initial fitting time is short, the capacitors require little maintenance, and it is usually very economic.

Who fits PFC capacitors?

A capacitor, along with all other power quality equipment, should be fitted and maintained by specialists in PFC. There are a lot of peculiarities unique to capacitor switched circuits that general electric maintenance personnel may not be able to recognise or deal with. 

Once fitted, PFC capacitors will help to improve electrical systems efficiency which will show a reduction in electricity bills. These benefits make a PFC capacitor highly valuable for places that have industrial electrical systems that may otherwise have been wasting power. 

If you would like to know more about PFC capacitors, then contact us, and we’d be happy to assist. 

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busbar image 2

4 Reasons to Apply a Busbar to Your Switchgear Solution

Busbar is a non flexible alternative to cables in terms of its movement but holds many other advantages as we will discuss below.

Essentially when power distribution reaches a certain size there will be multiple cables needed to meet the capacity, this increase in diameter and number or cores will increase the time to install, it will lead to a reduction in available space (if there is enough space) and when compared to a busbar solution will likely increase the cost to procure and install.

A busbar is a simple bar used for distributing power and it makes an excellent alternative to cabling. Busbars are especially good for use in switchgear systems as they offer several significant benefits. They are simple to install, you can reduce excess cables, and they can be easily maintained. Busbars are adaptable and customisable, so they will work in any switchgear system.

We offer a range of busbars designed for use in commercial and industrial applications. These are the key benefits of using busbars for switchgear.

Busbar image 1

1. Busbars can be advantageous over cabling

One of the main reasons to use a busbar is that it is usually much better than cabling. Complex systems with lots of cables take up a lot of space and look very messy. A busbar is far more compact than cabling, so your switchgear won’t take up anywhere near as much space. A busbar is also contained in a metal casing, so it is less prone to damage than a traditional cable. 

You will get less resistance with a busbar too. The extruded profile of the IP55 busbar distributes the current more efficiently and reduces resistance when compared with cables, so you experience less loss of voltage.

If you want a neater, more efficient, and safer alternative to cabling, busbars are perfect.

2. They are adaptable for different switchgear systems

The construction of busbars makes them very adaptable for different switchgear systems. They have a modular design with different elements joined by monoblocks so they can be modified to fit into any space. If you update your switchgear, it is quick and easy to adjust your busbar at the same time. The tap-off boxes can be replaced or moved easily without having to do extensive work and add more cables. Cables, on the other hand, can be very time-consuming and expensive to alter, so busbars are a lot more flexible.

3. The components are easy to understand

Busbars are made using very simple components that are easy to understand. Aluminium or copper conductors are encased in a resin to protect against oxidisation and maintain conductivity. 

The simplicity of the components means that our busbars are very easy to install and maintain, so you can ensure that your switchgear systems are always running efficiently.

4. You can arrange regular maintenance for busbars

Busbars require a lot less upkeep than cabling, but regular switchgear maintenance is still beneficial if you want to improve efficiency and avoid any problems with your switchgear system. Busbars are very easy to maintain because the components are very basic and the modular design means that they are easily dismantled and replaced, if necessary.

There are a number of potential problems that will be picked up during a routine switchgear survey. These include water ingression, contamination of busbars with foreign objects, exterior damage, and incorrectly functioning joints. A switchgear service does not take very long and it can help you avoid any major faults in the future, so you save money and your switchgear continues running as it should without interruption.

busbar image 3

How To Install A Busbar

The installation process for your busbar system is relatively simple. First, you must check all of the components to ensure that they are in good condition and have not been damaged in transit. If they are all intact, take the following steps to install your busbar.

busbar image 4

Connect the busbar elements

Begin by taking the protective foil from the end of the busbar elements and place them in position, making sure that the spacing between them is 30mm. It is important to make sure that all of the components are clear at this point. You can use a hair dryer to remove any dust. 

Next, place a joint block between the elements to connect the conductors to one another. Tighten the nut until the head shears off.

Casting the junctions

Once all of the elements are in place and secured, you need to cast the junctions using the moulds supplied. Start by applying neoprene seals to the mould and then spray demoulding agent inside and let it dry.

When ready, place the mould over the two busbar elements that you want to connect. There needs to be at least 2cm overlap on each side. Now, prepare the resin mix to pour into the mould. Make sure that the resin is completely clear and if it is cloudy, do not use it.

Pour the resin slowly to fill the moulds. When you are finished, tap them gently with a rubber hammer to get rid of any air bubbles. Finally, level the surface with a putty knife and leave the resin to set.

The hardening time varies depending on the temperature. It will take between 5 and 14 hours for it to fully cure. In a warmer climate, the resin will dry much faster. Once dry, you can use a grinding stone to remove any rough spots and make sure that the joint is even.

Test the busbar

Now that the busbar is installed, you can operate the switchgear system to ensure that everything is working correctly. You can also run resistance tests to check the efficiency of your new busbars.

Looking For A Busbar Solution?

If you are still using cables for power distribution in your switchgear, you are missing an opportunity to improve safety, keep things compact and tidy, and boost efficiency. By making the switch to busbars instead of cables, you can drastically improve the performance of your switchgear. They are also future-proof because they’re simple to change whenever you need to.

At AF Switchgear, we can help you find the perfect busbar solution. We have IP55 and IP68 models available, which are perfect for all kinds of commercial and industrial uses. If you have limited experience with busbars, our team can advise you and help you determine what kind of busbar is right for your switchgear. We also offer maintenance services for existing systems too.

Get in touch today to learn more about our products and services and how they can help you.

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Switchgear maintenance

How to Clean Electrical Switchgear Systems

Maintaining an LV switchgear system is a critical part of ensuring the safety of your employees and your facility. A dirty or malfunctioning switchgear system can cause a fire or an electrical outage, which can damage equipment and can potentially lead to serious injury. This page will outline the steps necessary to clean your electrical switchgear system safely and effectively.

Fully Isolate Your Switchboard

Before you begin cleaning your electrical switchgear system, it is important to fully isolate the system from all sources of power. Check the mains, generation, UPS, PV, and CHP power sources. Once the system is completely isolated, you can proceed with cleaning the switchgear safely.

Clean Using Filtered Suction Equipment

When you are sure that the switchboard is fully isolated and completely safe, you can begin cleaning. It is important that you only use specialist cleaning agents because non-specialist products can cause short circuits and damage the switchgear system.

Use specially designed filtered suction equipment with a non-metallic hose to remove all dirt, dust, and debris from the system. Check the ventilation grills to ensure they are not blocked with dust and dirt. Always work slowly and be careful with suction equipment so you do not damage any of the equipment while you are cleaning. Avoid using compressed air to clean your switchgear because it can push contaminants further into the components and cause more damage.

Wipe Surface Dirt and Dust Deposits From The System

After using suction equipment to remove hidden dust, you should wipe surface dirt and dust deposits from the switchgear. Use microfibre cloths and lint-free cloths to pick up all of the dust and ensure that you don’t leave anything behind. Soft cloths also help you avoid damaging the switchgear during cleaning.

You can also use cleaning wipes that are designed for use with switchgears. They use fast evaporating solvents that are not corrosive to metal or plastics, so you can clean stubborn dust without causing damage to the components.

Wipe all surface dust and dirt from the insulation bushings, stand-off insulators, electrical leads, busbars and busbar supports, and all other general equipment.

Conduct The 10 Crucial Post-Cleaning Tests

After cleaning, there are ten crucial tests you must conduct to make sure that the switchgear is functioning properly and there are no parts that require maintenance. Once you have cleaned away all of the dust and debris, conduct these ten steps for a full switchgear service:

  1. Inspect electrical joints and connections for overheating – you can spot overheating joints and connections by looking for discoloration, deformation, or blistering
  2. Torque test a sample number of bolted connections – If the torque values are too low, the bolt could come loose due to vibrations.
  3. Check operation of mechanical & electrical interlocks – the interlocks on a switchgear are usually put in place for safety reasons, so it is vital to check that they are functioning as they should and staying locked in the right position.
  4. Check the switchgear system’s instrumentation – if the readings on the instrumentation are not accurate or certain instruments appear to not be working at all, repairs need to be made.
  5. Check for loose fastenings – all fastenings on the switchgear system must be tight to ensure that the system is stable and safe. You can check for loose fastenings by visually inspecting the system and by using a torque wrench.
  6. Check if the indication lamps are operational – indication lamps demonstrate the state of the circuit and the position and also alert you to any emergencies.
  7. Check that the insulated barriers & terminal shields are in place – these barriers and shields protect you from electrical shock, so it is essential that they are in the correct position and not damaged.
  8. Check for the presence of moisture – moisture can cause electrical faults, so it is important to check for signs of water ingress and deal with any issues as soon as possible. You can do this by checking for condensation or water droplets inside the switchgear. Using a dry cloth to wipe the area will also pick up any small water droplets. If you do find moisture, the components need to be thoroughly dried before the switchgear is in operation again.
  9. Check warning & operation labels are visible – these labels provide important information about the switchgear and what to do in an emergency, so it is essential that they are visible and not damaged. Failing to properly display them could cause somebody to damage the switchgear or injure themselves. It may also be in breach of health and safety regulations.
  10. Prepare and submit a report for each switchboard – this report should include all of the information from the tests that you have conducted, as well as any repairs or maintenance that needs to be carried out.

Performing these switchgear maintenance tasks on a regular basis will ensure that the system functions safely and efficiently. When you have finished cleaning and making all of the necessary checks, you can replace the covers. The switchboard then has pre-energisation tests and checks to go through but once these are complete, you can restore power and continue using the switchgear immediately.

Conduct Maintenance Of The Circuit Breaker (ACB and MCCB)

It is also important to conduct maintenance of the circuit breaker when cleaning your switchgear. Follow these key steps to do so:

  1. Record details and protection settings of each circuit breaker – this information should be kept in a logbook so that settings can be checked after maintenance to make sure they are correct.
  2. Inspect conductors for signs of overheating – look for discoloration, deformation, or blistering around the conductor.
  3. Check if the castell interlocks (door/cable) are operational – this is a key safety feature so it is vital that it functions properly.
  4. Manually open, close, and trip the circuit breakers to exercise their mechanisms – do this 20 times, at the very least, but preferably more to make sure that the circuit breakers are operating smoothly.
  5. Check the arc chutes for blockages – blockages can occur when the splitter plates erode. Look out for a layer of soot on the plates or small chunks of metal that are causing a blockage.
  6. Check the main contact wear – when conductive components become too worn, the circuit breaker ceases to function properly.
  7. Check if the chassis shutter is operational.
  8. Secondary inject electronic trip units to prove tripping curves – this needs to be done for long time, short time, instantaneous, and ground fault systems.
  9. Perform low ohm continuity tests across the live to load side of the circuit breaker – make sure to record the results.
  10. Perform the dielectric test across adjacent poles (and in between) on the circuit breaker – make sure to record the results.
  11. Prepare and submit a report for each circuit breaker – include all of the recorded information from dielectric tests and continuity tests. Make a note of any repairs that need to be carried out too.

Need Help With A Switchgear System?

At AF Switchgear, we are experts in installing and maintaining switchgear systems for a range of applications. Services we provide include:

  • Switchboard modifications – installing MCCB, ACB, replace changeover controller, control circuit modifications (just to name a few)
  • Fault finding & rectification
  • Switchboard survey and investigations
  • Emergency call outs
  • Thermal imaging surveys
  • PFC servicing

Contact us today and we can give you some expert advice and, if necessary, help you select and install a new switchgear system.

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LV Switchgear

What is Low Voltage Switchgear?

Low voltage switchgear is a versatile system to distribute power safely and effectively either for a building or other type of structure that requires power.

Customers buy our switchgear for two reasons; primarily because we produce high quality, bespoke switchboards built to the latest industry standards and secondly for our customer service.

At AF Switchgear, we design and manufacture 400V three-phase equipment for both industrial and commercial use. In addition to 400V three phase circuits, 220V single phase circuits can be tapped off these systems but must be factored in during the design stage.

What is Low-Voltage Switchgear?

Switchgear or switchboards as they are commonly known are essentially the ‘brains’ behind all of the power going into and then around a building or structure. Power is fed into the switchboard and then distributes the power wherever it is needed via cables or bus bar systems.

When we say switchgear, we are always referring to ‘low-voltage’ switchgear’ (low voltage being 400V AC usually). Power is taken from the DNO (Distribution Network Operator) usually via an incoming transformer into a switchboard. The power is then distributed through devices known as circuit breakers, isolators or fused switches. Devices are situated in the same switchboard as the incoming supply and in sub-boards downstream if required.

Device sizes are determined by the size of the load or current needed to make a piece of equipment or system work. Note circuit breakers and fused switches are protective devices whereas isolators are not because they do not trip in an overload or fault condition. Isolators are usually used when manual switching is required to completely isolate the supply to or from equipment i.e., an output of a UPS unit for example.

There is usually at least one main LV Switchboard, which is fed by a mains transformer. The largest transformer that can be used to feed an AF Switchgear manufactured switchboard @ 400V is 4MVA, which can deliver up to 6300A and absorb a 100kA fault current. However, if different power streams are needed for resilience purposes, several transformers and/or main LV Switchboards can be utilised. Power is distributed through these boards and if required via sub-boards through a system called sub-distribution. Sub-boards are used to carry the power to the point of use or as near to it as it can get. In any event, for a new project a power discrimination study should be carried out by an electrical engineer to determine the sizes of cable/bus bars/circuit breakers etc to ensure equipment and conductors are appropriately sized to carry the current required for normal use and for prospective fault currents in the event of a short circuit. This is a very important factor for safety purposes.

To conclude, LV switchgear is an engineered solution constructed of a steel housing, containing copper conductors and a combination of circuit breakers and isolators used to control, protect, and isolate electrical equipment or systems to allow work to be done and clear faults quickly and safely when required. In this context, ‘low-voltage’ always refers to systems that feature voltages of 1000VAC (or less) or 1500VDC (or less).

Here’s how they work:

When is Switchgear Used?

Switchgear is used when there is a certain power requirement identified which needs to be controlled and distributed safely. In a residential property like a house, switchgear wouldn’t be necessary simply because the power requirements are too small unless the building is very large! Residential buildings usually feature a Consumer Unit which is a mini version of a switchboard and normally limited to a 100A @ 220V single phase supply. Commercial or Industrial switchgear can be rated up to 6300A @ 400V three phase so quite a difference!

Is Low-Voltage Switchgear Safe?

Large power users like datacentres can consume up to 100 Megawatts (1ooMW) of power – that’s 100 million Watts of power available to be used per hour (in comparison an electric kettle is about 3000 Watts (3kW)). Whether you have this amount of power available or a smaller power requirement, it’s crucial to have a system that can distribute power safely and effectively. If designed and installed incorrectly, power systems can be dangerous or even worse lethal to equipment and people.

A correctly engineered low voltage distribution system allows a building to deliver electrical supply safely. In the event of a fault, electricity can potentially damage equipment and endanger life. Electrical faults can also cause devastating injuries including severe burns or in the worst-case, death. All equipment manufactured and installed by AF Switchgear is designed to detect, isolate and clear electrical faults very quickly to protect life and equipment as much as practically possible.

As a class leading manufacturer, AF Switchgear must ensure the products it manufactures meets all relevant safety standards including statutory requirements such as BS EN 61439-2. To meet the latest standards, we carry out independently witnessed tests under laboratory conditions simulating electrical fault scenarios. This is called Type Testing and is a very expensive but necessary process.

Is Low-Voltage Switchgear Easy to Use?

You can’t buy large electrical switchgear systems from a wholesaler (unless in exceptional circumstances) or DIY store and is not intended for use by the general public. As a switchgear manufacturer, we build bespoke switchgear that is designed to the specification of the building or application it is intended for and is usually situated in a ‘controlled environment’ like a plant room or switch room. Some systems are easy to use and some systems are very complex. We always advise personnel to undertake training before operating any LV Switchgear as making a mistake can be costly or have catastrophic consequences if used incorrectly. We recommend that only a skilled, trained and suitably qualified person should operate live switchgear and that personal protective equipment (PPE) should be worn when switching devices for one’s own safety.

Why Choose AF Switchgear?

AF Switchgear is one of the UK’s leading manufacturers of specialist switchgear systems. Everything we produce is designed and built in-house to the latest industry standards. We also pride ourselves on the fact that each switchboard we build is bespoke and tailored to each customer. That means, for every customer, we design a solution that perfectly fits their specific applications with regards to both the physical size and electrical requirements.

We manufacture a variation of switchgear types and every customer we work with has a different set of requirements. For example, hospitals may require a system that can never suffer a loss of power at the point of use as this may endanger life. Other applications however may not need this level of resilience.

Here are some examples of specific requirements we would usually need to understand as a minimum when designing a switchboard:

If you require bespoke high-quality Low Voltage Switchgear for your project contact us today.

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