Electrical Power Systems

Five elements to ensure COMAH compliance

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Introduction

Owning and operating hazardous process plants, particularly those that fall under the COMAH1 regulations, requires compliance with a number of regulations, standards, and associated guidance documents.

Health, safety, and environmental (HS&E), operational and engineering managers are responsible for COMAH compliance and submitting COMAH Safety Reports. COMAH reports require evidence that your systems are compliant, and managed, tested, and maintained correctly. If you are unable to demonstrate compliance, the Competent Authority2 (CA) is likely to increase monitoring and intervene more frequently at your site, increasing the time and money you spend on demonstrating robust management systems.

The new Electrical, Control and Instrumentation (EC&I) operational delivery guide produced by the CA describes the approach that it follows for inspecting EC&I systems at COMAH establishments. This guide specifies the benchmark standards used to assess the management of risks by the operators of COMAH sites.

Schedule 4 of the regulations specifically references the need to provide sufficient information to the CA to demonstrate your compliance with the regulations. This includes design, construction, operation and maintenance

of equipment linked to major accident hazards. Failure to demonstrate compliance can lead to an improvement notice, a prohibition notice, or prosecution.

Three priority topics for EC&I systems are covered:

• Functional Safety

• Explosive Atmospheres (Hazardous Areas)

• Electrical Systems

In this paper, we will focus on the Electrical Systems topic, with an overview of the five main elements of a robust, compliant approach:

1. Hazard and Risk Assessment

2. Engineering and Design

3. Operation and Maintenance

4. Competence

5. Safety Management

For further information on the COMAH regulations more broadly, read our Guide to Achieving and Maintaining COMAH Compliance.

More details of the regulations themselves can be found on the links below:

http://www.hse.gov.uk/eci/index.htm

http://www.legislation.gov.uk/uksi/1999/743/contents/made

1 Control of Major Accident Hazards

2 COMAH is enforced in Great Britain by the competent authority comprising a number of public bodies including the Environment Agency (EA); the Scottish Environmental Protection Agency (SEPA); Natural Resources Wales (NRW) and the Health & Safety Executive (HSE)

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Electrical Safety - Objectives

Research by the Health & Safety Executive (HSE) shows that failure to adequately control process conditions, especially during normal operations, has been responsible for the loss of containment of hazardous substances. Electrical Control and Instrumentation Systems are there to provide prevention and mitigation measures against major accidents. Examples of such systems include instrumented process safety measures, such as trips, alarms and interlocks – including safety-instrumented systems. Plants also require protection against electrical sources of ignition.

In the case of Electrical Power Systems, the reliability and availability of utilities is of primary importance, alongside protection against large releases of electrical energy.

Inspections of electrical power systems are concerned with the prevention of major accidents through fire and explosion initiated by loss or failure of electrical systems. Inspectors will review the management, design, installation and maintenance of electrical power systems to ensure they provide the necessary reliability and availability to prevent major accidents, and so that they prevent danger to personnel. In its inspections, the Competent Authority will make reference to a number of benchmark standards (see box ‘Electrical Safety Benchmarks’).

Electrical Safety Benchmarks A number of current benchmark standards cover electrical power systems:

• BS EN 61936-1 – Common rules for Power installations exceeding 1 kVac

• BS EN 7671 - IET Wiring Regulations, Requirements for Electrical Installations

• BS EN 50522 - Earthing of power installations exceeding 1 kVac

• BS 7430 - Code of practice for protective earthing of electrical installations

• BS 6626 & BS 6867 - Codes of practice for the maintenance of electrical switchgear and control gear for voltages 1kV and above

• BS 6423 - Code of practice for maintenance of low-voltage switchgear and control gear

Compliance with the Electricity at Work Regulations and the Wiring Regulations is mandatory at all sites, whether they fall under the COMAH regulations or not.

Two additional HSE publications provide guidance on electrical safety:

• HSG85 Safe working practices

• HSG230 Keeping electrical switchgear safe

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The electrical safety hazard and risk assessment must consider implications for the health and welfare of personnel, and the implications of electrical failures for overall plant safety. The assessment should include:

Impact or catastrophic failure of electrical equipmentThis assessment should consider the impact or total failure, partial failure and transient failure. It should provide the plant owner with an understanding of where risks exist in plant operation.

The impact of electrical power failure on other utilities and systemsElectrically powered equipment is frequently used to provide risk mitigation. Examples include cooling systems, fire alarm systems, drench and deluge systems, gates, barriers, turnstiles and floodlights. In addition, loss of compressed air will result in gradual depressurisation of the air main, which could have implications for equipment across the plant.

Hazard and risk assessments must be undertaken by personnel who are competent and knowledgeable about the electrical distribution network, and who understand the processes that could be affected by failures. Risk assessment requirements are underpinned by the Management of Health and Safety at Work Regulations.

1. Hazard and Risk Assessment

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The engineering and design aspects of electrical systems safety include a number of important topics.

Earthing arrangementsA company must be able to demonstrate the appropriate design and verification of earthing systems for all electrical power distribution equipment. The requirements for earthing arrangements laid out in the Wiring Regulations include details of any equipotential bonding arrangements, adequate sizing of conductors and the details of the method selected to prevent danger from shock in the event of an earth fault (e.g., earthed equipotential bonding and automatic disconnection of supply).

Equipment selection and erectionAll electrical equipment must be suitable for the duty it is expected to undertake. A company must be able to demonstrate the sizing and selection processes used for new and refurbished equipment, safety measures adopted to prevent inadvertent contact, arc faults or lightning strikes; and consideration for the installation requirements of equipment installed inside and outside buildings.

The electrical supply characteristics must be assessed and documented e.g TNC-S supplies are sometimes found on Lower Tier COMAH sites as a legacy situation. This type of electrical supply can lead to unsafe conditions in hazardous areas and should be revised urgently if found.

Engineering Management systemUsers of switchgear must provide a management system to ensure its safe operation and to minimise risk. This system should cover:

• Policies and procedures covering the installation, commissioning, operation, maintenance and removal of the equipment

• An appropriate system of records

• Definition of responsibilities and training requirements

• Auditing of the effectiveness of procedures

Protection arrangementsProtection systems need to be checked and verified against the requirements of the electrical system design. The fault energy levels at the output terminals of each item of switchgear must be calculated, and the switchgear rating determined. Older switchgear, which was designed to obsolete standards, may need reassessment by the manufacturer or specialist assessors. The calculated fault energy levels must not exceed the rating of the switchgear.

The CA will look for evidence that sufficient analysis and rigour has been applied to the design to ensure it is inherently safe, or that robust protection has been designed in. It will want evidence that the associated protection systems have been designed and are being managed to appropriate industry standards.

Electrical distribution systems should be designed to discriminate faults and prevent failures cascading across the site.

Equipment layout and segregationThe location of equipment within the plant should consider its proximity to people and other equipment, safe access for maintenance and servicing and potential access requirements in the event of an incident, such as a fire or explosion.

2. Engineering and Design

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The CA will similarly look for evidence of good practice concerning the operation and maintenance of electrical systems.

Safe Systems of workThe organisation should have documented and enforced policies and procedures for working with live equipment, and for proving circuits are dead before maintenance work. It will also need to show how it handles authorisation levels and assesses the competency of all operations and maintenance personnel.

Modification policies and processes should also consider changes to electrical infrastructure. Such policies usually consider construction materials, composition, temperatures and pressures, but should also directly address changes to electricity distribution systems, at an appropriate level of detail.

Inspection, testing and maintenanceInspection, test and maintenance procedures need to consider a variety of different equipment types, including (but not limited to):

• Cables

• Switchgear

• Transformers

• Rectifiers

• Insulators

The maintenance regime should include policies, procedures and standards used for the isolation of equipment. They should outline who is authorised to carry out these operations and how their competence is validated.

Standards should also be in place specifying the appropriate test equipment for specific activities, and ensuring that operators understand any hazards inherent in the use of that equipment.

HV and LV equipmentHigh and low voltage systems require specific maintenance principles and procedures. Separate and detailed consideration is required for the maintenance of oil filled systems. These procedures should include thorough and validated testing and recommissioning procedures, and maintenance personnel require appropriate training and formal approval before working on each type of system. Regular refresher training is also important, which should be documented so records can be audited at a later date.

3. Operation and Maintenance

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Emergency backup systemsBattery powered uninterruptable power supply (UPS) systems should be tested periodically, and there should be a means to establish how long they can provide power when placed under load.

Where diesel generation sets are used, operation and maintenance procedures should extend to the management of the inventory and quality of the fuel supply. Consideration should be given to the impact of cold weather on the ability to supply fuel to the equipment.

All types of back-up system, including alternative separate supplies from the grid, require their own properly managed maintenance procedures and policies.

EarthingEarthing and bonding is required on all circuits, unless the site documentation or design states otherwise. Equipotential bonding should connect all exposed and extraneous conductive parts, again unless the site documentation states otherwise. The plant owner must be able to demonstrate that they understand the type of earthing systems in place, and that conductor and electrode materials been chosen correctly. Conductors should be sized according to BS7671. Earthing and bonding connections should be correctly installed at the designed connection points. Equipment should not rely on fortuitous contact for earth connections. Earthing systems also need to take account of the soil composition and resistivity of the site where they are installed.

Maintaining integrityThe plant owner must be able to demonstrate that appropriate steps are being taken to maintain safe operation as equipment ages. This includes steps to ensure that spare parts are still available for older equipment, and that ageing assets are managed properly.

Safety by design continues to evolve. Features such as insulated bus bars, IP2X equipment shrouding, Electrical Switchgear Forms of Construction (IEC 61439-2), vacuum equipment, SF6 equipment and arc-containment enclosures are all safety features that may not have been available as options when the site was built and equipped. Asset renewal also brings the opportunity to install remote circuit breaker operation, thus keeping operators outside the arc flash boundary. For these reasons, it is good practice to ensure that ageing electrical equipment is identified and put on the Asset Renewal Plan when appropriate.

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4. Competence

Ensuring the competency of personnel involved with electrical systems is mandatory under regulation 16 of the Electricity at Work Regulations.

Competence is a complex issue and detailed discussion lies beyond the scope of this paper. It is useful, however, to consider some of the key questions that an appropriate competence management system should be able to answer in this context.

• Who is the Responsible Person?

• Who is the Competent Person (also known as the Authorised Person or Senior Authorised Person)?

• Who is the competent person that analyses the effects of partial or total loss of power?

• How often are systems of work for electrical systems verified?

• Is this verification done independently?

• Are electrical systems audited to corporate or country/national standards?

• Where do the results of these audits go?

• Do audit results form part of an improvement programme?

• How have the people who undertake inspection, maintenance and testing been verified?

• Who audits and verifies the results of the inspection, maintenance and testing processes?

Even properly trained and competent personnel may not always be aware of what to do when things go wrong. Staff should be trained to recognise that there may be a need to change to a new system of work. That training should include a means to know how to refer a changed situation to the correct person in the management structure.

5. Safety management

As with competence, a plant owner must be able to demonstrate procedures and records for the safety management of electrical systems.

The plant’s safety management system should have separate procedures for high and low voltage systems. Refresher training for personnel should be scheduled on a routine basis, just like inspection.

Accurate, up to date records are essential. They should include:

• Network diagrams

• The asset register

• Maintenance records

If there is any doubt as to the accuracy or validity of records, a new inventory should be made as a matter of urgency.

The safety management system must be effective, up to date, and enforced. This requires:

• A systematic review process for policies and procedures

• A mechanism to ensure that Safe Operating Procedures are followed

• A change management system that includes the effects of changes to the electrical distribution system, with sign off and approval from appropriate personnel

Spot check1. Are all the personnel working on your electrical

power systems

a. Competent?

b. Qualified?

c. Formally authorised?

2. Do you know

a. What assets you own?

b. What you are responsible for?

c. That there are suitable maintenance procedures and policies in place?

3. For your electrical infrastructure, do you have

a. Single line diagrams?

b. Fault studies?

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How GSE Can Help COMAH requires adherence to a number of regulations, standards, and associated guidance documents. As your workforce turns over due to retirement and competition, are your systems at risk? As you continuously improve plant operations, adding automation and improved processes, are you forgetting that your functional safety requirements must be managed, tested, and maintained, as well?

GSE believes that following a structured process is the key to compliance, and more importantly, to ensuring the safety of your people, plant, and environment. We would like to discuss all of your COMAH compliance needs, how our staff of experts can keep your site personnel abreast of new legislation, and how we can help you implement any changes required to maintain compliance.

We have an excellent track record providing these services in numerous high-hazard environments, including major Oil and Gas and Chemical Operators, along with smaller manufacturing facilities.

Our approach is to discuss your facilities and operations, and with a full understanding of the extent and roles that your existing systems play in reducing risk, propose a detailed solution to help you achieve and maintain compliance.

For further advice and recommendations please contact us at Engineering@gses.com

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About GSE SystemsGSE Systems, Inc. is a world leader in real-time high-fidelity simulation, providing a wide range of simulation, training and engineering solutions to the power and process industries. Its comprehensive and modular solutions help customers achieve performance excellence in design, training and operations. GSE’s products and services are tailored to meet specific client requirements such as scope, budget and timeline. The Company has over four decades of experience, more than 1,100 installations, and hundreds of customers in over 50 countries spanning the globe.

Information about GSE Systems is available at www.gses.com.

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