Electrical Safety in Wind Turbines

Electrical Safety in Wind Turbines

Safety in and around a Wind Turbine Generator is exacerbated for the following reasons:

  • The remoteness of most turbines to medical facilities means that any accident that may require hospitalisation can quickly turn catastrophic due to the time taken from the time of accident/injury to the time of receiving professional medical assistance. 

  • The confined space. Within most wind turbines, the electro-mechanical parts of a wind turbine generator are typically in very confined spaces, further compounded by multiple people being in an area at one time and exit routes often tricky to negotiate. In the event of any incident, the path of escape/exit is not straight forward.

Top 5 hazards on a Wind Turbine Generator (excluding transfer on and off an offshore WTG)

Hazard #1 – Falls from Height
Hazard #2 – Confined Spaces
Hazard #3 – Electrocution/Arc Flash
Hazard #4 – Fires
Hazard #5 – Moving Parts

SKANWEAR® is a global leader in Arc & Flame Protective Clothing & PPE, so Hazard #3 is a particular focus.

Some basic Electrical Safety Fundamentals to consider & implement

1. UNDERSTANDING YOUR ARC FLASH & SHOCK RISK IN A WIND TURBINE

Shock Risk

Well, this is pretty simple, don't touch exposed conductive parts. It is not quite as simple as that. A shock risk assessment is going to look at many more things, including but not limited to: 

  • Voltage Level
  • Distance to the worker in relation to the voltage level (Boundaries, IEC 50110 is a fantastic standard to aid in the definition of these boundaries)
  • Type of equipment
  • Condition of equipment
  • Environment

Once all the factors have been accounted for the level of risk is understood, mitigation techniques can be put in place, which could include: 

  • Installation of permanently mounted absence of voltage indicators to all equipment
  • Voltage rated insulated mating installed on the floor area around all electrical equipment
  • Wearing EH (Electrical Hazard) or DI (dielectrically insulated) boots
  • Use voltage rated gloves
  • Insulated tools
  • Wearing personal presence of voltage indicators like the Proxxi or Aladin
  • When proving for the absence of voltage using a non-contact device and proving unit prior to a contact device and proving unit

ASSESSING YOUR RISK OF ARC FLASH IN A WIND TURBINE

With calculations:

Detailed power system studies typically consist of a:

  • Short-circuit study
  • Protection coordination study
  • Load flow study
  • Arc flash hazard Analysis (incident energy calculations). These calculations can be carried out in line with the following standards:
    • IEEE1584-2018
    • DGUV-I 203-078 (formerly BGI/GUV-I 5188E)
    • NFPA® 70E 2021

Modelling a wind turbine typically includes the main circuit breaker at the base of the tower and the doubly-fed induction generator located in the head of the wind turbine, otherwise known as the nacelle. However, there are many other electrical systems and equipment throughout the wind turbine.

Unfortunately, the level of detail required to correctly model and label these components inside the turbine is often overlooked. The information contained on the arc-flash labels results from a detailed arc-flash analysis of the turbine's electrical system based on the available short-circuit energy at the incoming switchgear used to protect the electrical equipment within the nacelle.

The label attached to an electrical device generally provides the required level of personal protective equipment (PPE) and other vital information items (see Figure 1). Some countries have a standard for the contents of the label. Some advice from around the world is to keep it as simple as possible to minimise relabelling.


(Figure 1)

  1. Danger or Warning header.

A common guideline is to use the "Danger" header when the voltage is over 600 or when the incident energy is over 40 cal/cm2. If it is less than these thresholds, an orange "Warning" header is typically used.

  1. "Incident Energy at" the corresponding working distance.

"the dimension between the possible arc point and the head and body of the worker positioned in place to perform the assigned task."

OR

  1. Personal Protective Equipment (PPE).

Each hazard risk category requires a different level of protection. Categories range from 1 to 4 as defined within NFPA 70e. However, you may choose your own company categories.

  1. Arc Flash Boundary.

This is the shortest distance at which a person working at the time of an arc-flash may receive injury (the onset of a second-degree burn or worse, 1.2 cal/cm2) if not adequately protected by flame-resistant (FR) clothing. 

  1. "Shock Risk When Cover is Removed".

The nominal system  voltage of the equipment.

Without Calculations:

When you do not have a power system study completed and arc flash hazard data available on detailed Arc flash and Shock warning labels or results tables, then the Arc flash PPE category table method can be used.  Please see CSA Z462 Tables 6A/6B or V.1 or NFPA 70E Table 130.7 (C) (15) (a)/(b).

2. IDENTIFYING YOUR ARC FLASH & SHOCK RISK IN A WIND TURBINE

First, on what equipment is there an Electrical Safety Risk in a WTG?

  • Generators
  • Control Panels
  • Slip Rings
  • Batteries
  • Capacitors
  • Transformers
  • Collector System
  • Substation
  • Test Equipment

Secondly, what activities pose the most significant Electrical Safety Risk?

  • Operation of equipment
  • IR inspections with equipment open
  • Racking in and out of circuit breakers
  • Insertion/removal of equipment in an energised state
  • LOTO (proving the absence of voltage)
  • Fault Finding & Testing in an energised state is by for the highest risk task (in the authors' opinion)

In the event of an electrical fault, you can check your circuit in two ways: the dead (isolated /safe) state or in an energised state. An energised state is where the most significant risk is posed and when you re-energise a circuit and test. 

With so many different types of equipment in a WTG, all of which will have different available incident energy, cal/cm2 is where using a layered PPE system to achieve the correct level of protection for each piece of equipment shows its advantages. A two-stage simple system is the most effective. Try to cover the most significant percentage of the hazard range with the first layer and the second layer for higher risk less frequent activities.

ARC FLASH CLOTHING (Layering for Comfort & Safety)

At SKANWEAR we have a dedicated technical team that provide impartial advice to help businesses understand the level of arc flash risk they are exposed to and advise on how to achieve the protection they need in the easiest, most functional and cost-effective way.

Examples below of layering combinations:

NOTE:  You cannot just add two layers of Arc Flash Clothing together and work on an assumption that 8 cal/cm² + 8 cal/cm² = 16 cal/cm².  Your Arc Flash Clothing provider should be able to evidence certification to confirm what any recommended layering options equal to when combined.

Match your protection to the risk

In need of help and advice?  Contact our technical lead today:  Anthony.long@skanwear.com 

3. Create an electrical safety program or Wind Turbine Safety Rules.

According to a globally recognised NFPA 70E Electrical Safety Guidance, key components of an effective electrical safety program are:

  1. Awareness and Self-Discipline
  2. Electrical Safety Program and Principles
  3. Electrical Safety Program Controls
  4. Electrical Safety Program Procedures
  5. Hazard/Risk Evaluation Procedure
  6. Job Briefings

Some more specific aspects to include in your electrical safety programme are.

  • Use of Insulated Tools        
  • Use of correct Arc & Flame Protective Clothing & PPE      
  • Lock Out/Tag Out Equipment & Procedures    
  • Job Hazard Analysis / Risk Assessments         
  • Defining of Specific Work Zones             
  • Arc Flash Hazard Analysis         
  • Safe Approach Distances
  • Switching Procedures         
  • Hot Work Permits             
  • Confined Space
  • Cadence of Safety Meetings & Training        
  • Incident Reporting
  • Electrical Maintenance Program
*Please see NFPA 70e or CSA Z462 for more details on ESP contents.

4. Maintaining your Electrical Safety Plan. (Start with the End in Mind)

As soon as the Electrical Safety Plan is finalised, it will be probably out of date. Some questions then arise: "How do you stay abreast of constant changes in codes, standards, tooling, electrical equipment, electrical designs, and legislation to keep the Electrical Safety Program current? What metrics will the Electrical Safety Program use to measure performance?" Upper management will want to see how an Electrical Safety Program saves money, reduces downtime, lawsuits, and reduces workman's compensation/insurance cost.

5. Implementing your Electrical Safety Plans

Once your Electrical Safety Program is complete, what are the next steps? Implementation of the document is the most important and most challenging step to accomplish. Implementing will never end because the document will remain live, undergo reviews and updates, and new employees will require training on the Electrical Safety Program.

To be successful at implementation, involving the stakeholders and day-to-day workers is an important part. Including managers, supervisors, and workers creates the safety culture that is needed in order to adopt the Electrical Safety Program and live a safe lifestyle.

The first step towards implementation is to provide training to make the technicians Qualified Electrical Workers. The technicians have to be trained on the hazards, processes, procedures, and risks to become qualified and confident around your electrical equipment. Reinforcement training is required to update the individuals on your Electrical Safety Program changes and review past training. Having fully-involved qualified workers onsite will breathe life into the Electrical Safety Program and help promote a safe working lifestyle throughout your company.

The next step is to ensure steps have been taken to ensure the workers and contractors are protected. It is essential to verify the arc flash study is correct and update to date. Equally important is to verify the arc flash labels are correct on each piece of gear and easily identifiable. Also, make sure the wind farm meets the other electrical standards essential to the wind farms operation.

Once you have trained your workers and your wind farm is compliant, develop and implement safe work practices. Safe work practices can vary from wind farm to wind farm, so be sure to understand what work practices or procedures are likely to change and maintain the safe work practices for those specific tasks. Up-to-date, safe work practices will help the employees understand the task at hand, the risk at hand, and how to safely and adequately perform the task. These safe work practices will also help the employee determine the proper PPE required for the job and if they need any permits to perform the work. Developing consistency among your fleet is essential, and the ESP is one method to do so.

Lastly, whenever the Electrical Safety Program is revised, what is the methodology for getting the changes out to the employee level? How are these changes implemented, and how are they verified?

Implementation will be the longest step in the process, but it is the most important step. Implementing effectively will be vital to the Electrical Safety Program, along with creating a safe lifestyle.

6. Documenting your Electrical Safety Program

Providing written documentation for the corporation to reference and for the technicians to use will build consistency of corporate safety policies and procedures across each wind farm. The written documentation is also imperative for third party contractors performing work at the job site to safeguard against any confusion about onsite safety.

Examples of documentation critical to an Electrical Safety Program:

  • Policies
  • Switching Procedures
  • Performance Objectives and Standards
  • Procedures
  • Permits
  • Job Hazard Analysis
  • Audits   
  • Improvement Plans
  • Training Records
  • Incident and Near Miss Recording

If the documentation is used as a reference, resource, or is seen as a benefit to the employee, it can be a massive asset to your Electrical Safety Program. On the other side, if not appropriately used or seen as a burden, it can negatively impact morale and your Electrical Safety Program.

A way to lessen the perception of burden and gain worker collaboration in an ESP is to hold a kind of ESP AGM before reviewing the document to collate any document users comments and ideas. Having worker engagement and acting upon it genuinely makes the electrical safety program a company program with everyone owning it.

An ESP is best published as a go-to guild and should always be on hand for your electrical workers, so with that in mind and bulk been a concern for WTG workers having enough to carry already, think about other ways to publish the ESP. On workers smartphones or tablets, a weatherproof copy in each WTG with the onboard safety equipment and individual risk assessments for each piece of electrical equipment and SOPs.

7. Evaluating and Improving your Electrical Safety Program

As discussed previously, the Electrical Safety Program is a living and breathing document. Because of this, it will constantly need to be reviewed, edited, and revised. 

Evaluating the Electrical Safety Plan can be done in several ways. One method is to perform internal audits on the documented processes and procedures to find ways for improvements. Another possible method is to use a third party to perform audits on your Electrical Safety Program. It is good to get a fresh set of eyes on the program. Incidents or near-misses must be investigated to determine if additional policy or procedures need to be implemented. This is also an effective metric to measure the success of the ESP against. Lastly, unannounced site visits by the auditors can prove to be beneficial.

Best practices from the evaluations will need to be implemented into the Electrical Safety Program.

7. Creating a culture of awareness around Electrical Safety

An Electrical Safety Program is crucial to develop the safety culture within the organisation. With the ever-changing markets and legislation, the Electrical Safety Program will need to be constantly revisited to ensure the newest regulations are followed, and the procedures and work practices are up-to-date.

Implementing the program from a corporate level to a site level is challenging but extremely important to promote the safety culture throughout the whole organisation.

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Looking for support? Contact our specialist Anthony Long today 

Anthony Long
Technical Director
Email: anthony.long@skanwear.com
Mobile:  +44 (0) 7584 607 882

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