Glossary and terminology

Aerial asset monitoring: Aerial thermal imaging of assets via our National Grid helicopter

Air Blast Circuit Breaker: An automatically operated electrical switch that uses air to protect an electrical circuit from damage caused by excess current from an overload or short circuit

AIS: An air insulated switchgear composing electrical disconnect switches or circuit breakers used to control, protect and isolate electrical equipment

Archaeological survey: Field surveys and research to collect information about the location, distribution and organisation of past human coaches on a chosen site  

Asset monitoring: In-depth insight through consultancy on your assets 

Bay: High-voltage transmission connection for larger projects (up to 1.8GW) comprising a portion of a National Grid substation (bay) to accommodate client assets plus busbar connection

Capital Delivery: The construction part of Electricity Transmission. It delivers our large projects such as the building of new substations or transmission lines. It also delivers asset replacement or refurbishment works

Commissioning: The post-construction testing of new or modified assets, in accordance with UK and National Grid codes, prior to gong live on the HV transmission system 

Construction management: The turnkey service available from National Grid that delivers both the connection plus the client owned assets associated with the connection

Consultancy: The Engineering and Consultancy Solutions team (ECS) provides consultancy on engineering services for your business and delivers a wide range of products that cover the full life cycle of assets    

Customer contracts: The team within Capital Delivery accountable for the delivery of any client owned assets (if requested) associated with a transmission connection

Decommissioning services: At the end of site life, ECS manages the complete disconnection, decommissioning and removal of the site. This includes customer owned assets on their premises but also within National Grid land

Ecological survey: A survey and research to assess an area for valuable plants, habitats and animals to support local planning authorities assessing potential adverse effects on wildlife in the project area

ECS: Engineering and Consultancy Solutions 

EMF management: Electromagnetic field exposure assessments 

EPC: Engineering, procurement and construction of new high-voltage transmission assets  

Flood and natural hazards risk management: Consultancy support and advice in developing an impact assessment of flooding and water-related geo-hazards 

GIS: Gas insulated switch gear (usually SF₆ – see below) composing electrical disconnect switches or circuit breakers used to control, protect and isolate electrical equipment

Ground Investigation: Desktop and field surveys to determine ground conditions prior to construction work to reduce hidden risks that could delay or impact a project 

Harmonics: Unwanted higher frequencies, which superimpose on the fundamental waveform creating a distorted wave pattern 

High voltage: We refer to high voltage being the transmission system voltages 132kV-400kV 

High-voltage services: Maintenance, consultancy and support services for high-voltage sites 

High-voltage connections: Connecting high-voltage client projects the national transmission network

Incident response: Incidents such as power cuts, alarms etc. that are responded to as a matter of urgency 

Licensed: Our Licensed business carries out work that we have agreed with our regulator, Ofgem. This includes new network connections and efficiently maintaining and replacing the existing network to make sure it continues to be safe and reliable

Noise management: Our Noise Management service provides noise impact assessments, monitoring, acoustic modelling and reports, and noise complaint management

Oil management (OMU): Our portable Oil Management Unit provides sampling, testing, analysis and advice, including replacement, reconditioning and reclamation 

Project Management: The service available from National Grid which provides professional project services to manage all aspects of an HV connection project

SF₆: Sulphur hexafluoride (SF₆) is a highly effective electrical insulator used in high-voltage electrical applications. It's a greenhouse gas that has a global warming impact of 22,800 times that of carbon dioxide 

SF₆ management: Handling and storage of SF₆, plus gas leak repairs, emptying and top up 

SF₆ surveys: On-site leak detection surveys using specialist thermal imaging technology 

SME: National Grid subject matter experts available to clients to assist with ALL aspects of HV connection delivery and asset maintenance