The risks surrounding the operation of electrical switchgear systems are defined in detail and mitigating these is an important aspect of any health and safety policy. As set out by regulatory bodies like the HSE, in publications such as Electrical Switchgear Safety (INDG373), there are a number of important factors to consider. These are well documented and include:
- Providing the correct training;
- Ensuring regular maintenance;
- Ensuring staff know the rules and their responsibilities;
- Carrying out regular risk assessments and acting on their findings.
The use of trapped key technology to ensure the safe operation of electrical switchgear systems has been established since the early 1920s. There are two principal issues that interlocking provides a solution for: the correct operation of switchgear equipment – reducing the possibility of arc flash – and the provision of safe access during maintenance.
Trapped key interlocks offer seven distinct advantages when used to safeguard MV and LV switchgear systems:
- They prevent personnel from accessing live terminals and cabinets.
- They protect equipment by ensuring it can only be operated safely.
- They can be operated by less skilled personnel, reducing training costs.
- They can reduce unintended outages caused by incorrect operation.
- They perform in harsh environments.
- They deliver a solution that satisfies the higher global MV standard IEC/EN 62271-200, defined as ‘accessible and interlocked’ as opposed to ‘accessible by procedure’.
- They allow the integration of LV and MV switchgear systems, different manufacturers’ equipment, and subsystem elements such as breakers and transformers.
Each switchgear system will have its own set of operational and maintenance requirements, and it is important these are taken into consideration before implementing a safety solution. In general, trapped key interlocks are highly flexible and provide integrated and retrofit solutions across a wide range of manufacturers’ equipment.
By: David Hughes, Sales Director, Castell Safety International Ltd.