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Thorne & Derrick: Electrical Safety in Wind Turbines

Posted on 29 February 2024

Electrical Safety

Any industrial or commercial workplace requires arc flash and electrical safety training, and it is essential in order to make sure your staff members know what they need to do to remain safe.

Leaf Electrical Safety is an electrical safety company that can provide expert advice on electrical safety to help teams build processes and improve safety culture. Working primarily across Canada and the USA, they help solve your industrial electrical safety problems.

Electrical safety compliance training should keep you on the edge of your seat, wanting more, because it will highlight the dangers that your team faces on a daily basis. Special thanks to Jon Travis for the kind permission to republish.

→ See original article here!

 

WIND POWER FACILITY ELECTRICAL SAFETY

In our ever-changing renewable world, the safety of personnel is still and should remain a paramount concern. Wind Energy Conversion Systems (WECS) are some of the more prominent types of renewable generation whose safety concerns are exacerbated by two main factors:

  • Remoteness: due to the nature of wind turbines being remote and/or offshore, any hospitalisation can turn into a race against time.
  • Confined spaces: the electrical components and work areas within a wind turbine are typically in confined spaces, which becomes more problematic when you add multiple workers into the mix.

WHAT ARE THE ELECTRICAL SAFETY HAZARDS

IN WIND TURBINES?

In order to mitigate hazards and allow for adequate protection, WECS equipment and operators should be adequately equipped to deal with the following main hazards issues that commonly occur in WECS:

  • Arc Flash
  • Shock
  • Overloaded Circuits
  • Defective Insulation
  • Wet Environment
  • Damaged or Worn Equipment

ARC FLASH RISK IN WIND TURBINE

Potential arc flashes in WECS are potentially life-threatening issues which require detailed analysis and physical protection to be accounted for. Arc flash hazard analysis (incident energy calculations) is typically used and utilises standards such as IEEE 1584-2018 to perform the calculation. Once the calculation is made and the proper arc flash boundaries are determined, personal protective equipment (PPE) can be assigned based on the calculations (see CSA Z462 for more details).

SHOCK RISK IN A WIND TURBINE

Shock risk, like an arc flash, is a potentially life-threatening hazard if not properly accounted for. Usually, a shock risk assessment is performed to look at key system parameters such as voltage level, shock boundary, environment, equipment type, and condition.

OVERLOADED CIRCUITS

Overloaded circuits can cause various problems and increase the risks of shock and arc flash considerably if not protected and isolated properly. Preventative measures can be taken through routine inspection of protection devices and physical circuitry (with proper PPE) to check for any abnormalities in the equipment.

DEFECTIVE INSULATION

Defective insulation can cause system malfunction and exponentially increase the potential arc flash and shock risks. Regular insulation resistance (IR) tests, whose procedure for electric machinery is highlighted in IEEE 43-2013, should be performed to test the dielectric strength of the insulation.

WET ENVIRONMENT

Wet surfaces can prove hazardous to people as well as electrical equipment. In order to reduce these potential hazards, regular equipment checks should be carried out on the exterior and interior of the WECS for potential water seepage/damage.

DAMAGED OR WORN EQUIPMENT

Equipment can be compromised from its normal working state for a variety of reasons, but compromised equipment can cause major problems if it is not repaired or replaced quickly enough. To mitigate this, scheduled maintenance procedures should be made and followed (see CSA Z463).


ELECTRICAL SAFETY PRECAUTIONS FOR WIND TURBINE WORKERS

PROPER PERSONAL PROTECTION EQUIPMENT

Each hazard risk category requires a different level of protection. Categories range from 1 to 5 as defined within CSA Z462 and laid out below as follows:

PPE category 1 2 3 4 5
Incident Energy Up to 4 cal/cm² Up to 8 cal/cm² Up to 25 cal/cm² Up to 40 cal/cm² Up to 75 cal/cm²

Figure 1:PPE category as defined by CSA Z462


ARC FLASH BOUNDARY

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

LABELING

Labelling is defined in CSA 22.1-18 for both small (64-300) and large (64-400) wind turbines as “a permanent marking” that must be created near an easily accessible location near the disconnecting for the wind turbine output circuit (64-300) or base of the tower (64-400) and display the following critical information:

  • Overcurrent protection values provided by the wind turbine for the stator and rotor, if applicable;
  • Short-circuit current rating (SCCR);
  • A brief system description, including the type of generator (synchronous or induction);
  • Rated output current; and
  • Rated output voltage at the grid connection to the turbine.
  • Warning notice (large turbines only)

Furthermore, arc flash and shock hazard labels should be provided for large wind systems. These labels are covered in CSA Z462 Annex Q, which highlights procedures for labelling arc flash hazards and shock protection. The minimum arc flash label requirement per CSA 22.1-18 (Canadian Electrical Code Part 1) is:

Arc Flash Label for Wind Turbines

Figure 2:CSA Arc Flash label template for CSA 22.1 Requirements

Whereas the CSA Z462 recommends that the label look something more like:

Arc Flash Label

Figure 3:CSA Z462 Annex Q Recommended ARC Flash label structures


WIND TURBINE GROUNDING

Like any generator, the WECS should be properly grounded and follow CSA standards and IEEE 142. Proper grounding of turbines follows the general ruleset of AC connections as defined by CSA 22.1 Section 64-312 as:

  • 1) Exposed non-current-carrying metal parts of towers, turbine nacelles, other metallic equipment, and insulated conductor enclosures shall be bonded to ground in accordance regardless of voltage.
  • 2) Metallic towers or supporting structures shall be bonded to the ground with a minimum No. 6 AWG.
  • 3) Guy wires used to support turbine towers need not be grounded.
  • 4) Towers or structures shall be grounded by means of grounding electrodes to limit voltages imposed by lightning.
  • 5) Notwithstanding Subrule 4), metal towers located on steel-supported buildings shall be bonded to non-current-carrying metal parts of the building.

FAULT FINDING & TESTING

To effectively find faults in a WECS, proper fault monitoring relay devices should be installed particularly:

  • 50 – Instantaneous Overcurrent Relay
  • 51 – AC Time Overcurrent Relay
  • 59 – Overvoltage Relay

These devices will be able to monitor and indicate the levels of key parameters such as voltage and current.


ELECTRICAL SAFETY STANDARDS AND TRAINING REQUIREMENTS FOR THE WIND ENERGY INDUSTRY

CSA 22.1-2018 lists several safety requirements for both small and large wind turbines (64-300 tot 64-414), including marking, maximum voltage, insulated conductors, wiring methods, overcurrent protection, disconnecting means, grounding and bonding, maintenance receptacles, lightning protection, surge protection and system demarcation (large turbine).

Training requirements are highlighted in Annex U of CSA Z462, which highlights procedures for human performance in electrical safety. It highlights risk control methodologies and procedures for human performance, such as

  • Job planning and pre-job briefing tool
  • Job site review tool
  • Post job review tool
  • Procedure use AND adherence tool
  • Self check with verbalization
  • Three-way communication tool
  • Stop when unsure tool
  • Flagging and blocking tools

Thorne & Derrick

ELECTRICAL SAFETY PROVIDERS

Thorne & Derrick protect substation engineers, asset managers, SAPS, cable jointers, overhead linesmen and utility workers with PPE and safety equipment: this includes insulating glovesarc flash clothing, voltage detectors, insulating matting and portable earthing to ensure worker safety when carrying out repair and maintenance on LV-HV switchgear, transformers, substations and turbines.

All of our Cable Connection & Energisation Accessories including Medium & High Voltage joints, terminations, connectors and cleats are tested to the latest international standards and supporting ranges of professional installation tools are stocked to reduce incident, accident and downtime to plant and people.

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