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 the Purpose of 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 that 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:
- A mains transformer or backup generator supplies the switchboard via cables and/or busbars to an 'incoming' circuit breaker/device, which is usually an ACB (Air Circuit Breaker) or an MCCB (Moulded Case Circuit Breaker).
- On the output side of the incomer devices, power is distributed around the switchboard via internal copper bars that feed smaller rated circuit breakers, again ACB's or MCCB's. These devices are referred to as outgoing ways.
- Power is distributed from these smaller devices directly to equipment or to sub-boards which feature even smaller rated ACB’s; MCCB's or even smaller MCB's (Miniature Circuit Breakers).
- Most of the time, voltages fed into switchboards in the UK and Europe for commercial or industrial applications are three-phase supplies at 400VAC.
- All ratings for circuit breakers or isolators are rated in Amperes (Amps).
When is Switchgear Used?
Switchgear is used when there is a certain power requirement identified that 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 data centres 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:
- Prospective Fault Current Levels in kA
- Voltage (V), Frequency (Hz) and Current (A) rating of the incoming supply
- Number of incoming and outgoing circuits required
- 3 or 4 pole Circuit Breakers/Isolators/Fused Switches required
- Front or Rear Access to the board (for maintenance purposes)
- Logistical, installation and spacing restraints/requirements
- Energy Metering needs
- Thermal imaging again for maintenance purposes
- Cable or bus bar entry requirements
- Form Factor desired
- Circuit identification needs
- Is Restrictive Earth Fault required (protects the Transformer)
- Is Surge Suppression needed
- Any Power Factor Correction equipment required
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