LV switchboards generally connect to a building incomer and act as power distribution units directing electricity from the incoming supplies and other sources to circuits within a building. Downstream circuits may be further distributed through sub-boards.
Other power sources can include standby power generating sets, uninterruptible power supplies, renewable power and energy storage systems. The circuits supplied include critical power paths (IT and datacentres), essential services (lighting, security, heating and cooling) and non-essential services.
Two options to consider when designing an LV switchboard include Transient Voltage Surge Suppression (TVSS) and Power Factor Correction.
As an LV switchboard is connected to a building incomer it is indirectly connected to a local substation and the National Grid. Lighting strikes are not uncommon and can induced into electricity supply lines transient surges that can damage or destroy downstream devices.
TVSS devices built-into an LV switchboard are designed to suppress high-kV rated surge voltages and transients and protect both the LV switchgear and downstream devices. TVSS devices are installed in parallel to electrical supply circuits and divert excess energy to earth. They degrade when faced with short term energy surges and/or self-destruct and are generally designed for easy replacement without the need for downtime.
Power Factor Correction (PFC) systems are built-into LV switchboards to improve site power factors. Large industrial sites charged using half-hourly metering incur reactive power (kVAR) charges from their local district network operators (DNO).
Reactive power is the electricity required to power inductive load devices with poor power factors. Such devices can include electrical motors, lighting and industrial equipment. Power factor is a ratio measurement of the real power kilo-Watts (kW) to the apparent power kilo-Volt-Amperes (kVA) drawn by electrical devices.
DNOs aim for a power factor of at least 0.95. When real power = apparent power the power factor is at Unity and the electrical efficiency is 100%. When an industrial site has a power factor of 0.8, this equates to 80% efficiency and 20% wasted energy. The site is effectively charged for the extra power that the DNO has to supply in order for the loads to work. This power is ‘wasted’ energy.
Power factor correction can also be installed as a separate system to an LV switchboard. In either case the installation is in parallel to the electrical supply circuits.
B&S Group is one of the UK’s leading LV switchboard manufacturers. We operate our own in-house metal fabrication and power coating facilities and supply both custom and modular LV switchboards for industrial, commercial and datacentre applications. Please contact us for more information.