Power Zero deliver onsite energy generation and energy storage systems in a sustainable manner across the UK. They deal with a variety of sectors such as manufacturing, data centres and agriculture.
Their site at Denby Pottery is comprised of a 2.1MW Solar PV Solution, which powers the Denby plant.
Requirements
Power Zero were actively aspiring to understand and manage the arc flash risk on their Solar PV Solution at Denby Pottery in Derby. As a lead consultancy in arc flash risk assessment and management Electrical Safety UK Ltd (ESUK), were contacted by Power Zero to provide a proposal to carry out an arc flash risk assessment study.
Power Zero required a suitably qualified and competent contractor to successfully deliver the arc flash study to their requirements and provide the necessary information to assist them with managing their arc flash risk.
Solution
Electrical Safety UK Ltd carried out a free of charge visit to Denby Pottery to discuss and agree with Power Zero the scope of work and undertake a pre-assessment to determine and collect the data of their electrical network. Whilst at Denby Pottery ESUK provided a short presentation on arc flash awareness and the ESUK approach for the arc flash study.
The site visit with Power Zero enabled ESUK to provide a fixed price proposal for the Arc Flash Risk Assessment Study and agree project milestones as well as a completion date.
Approach
ESUK agreed the scope and strategy with the Head of Solar Delivery and the Solar Project Engineer at Power Zero.
ESUK conducted an in-person discovery phase of the work, gathering and verifying site installation information on the electrical distribution system network.
The following information was necessary for us to accurately model the solar arrays for the arc flash risk assessment: how many strings were in the array, how many solar panels made up a string, and whether the solar panels were configured in series or parallel. This information was collated on our tablet using our EasyPower© software, which allows photos to be taken of the specific equipment or protective devices and tagged to the equipment.
This collected information enabled us to develop an initial single line model of the distribution system using the EasyPower© software to then provide a verification and outstanding information data pack where data could not be confirmed, or equipment could not be safely isolated for operational reasons during the discovery phase.
Following the provision of this outstanding information, a full arc flash analysis was conducted on the Power Zero Solar PV Solution system model using the EasyPower© software to undertake: –
- Short Circuit Analysis to IEC 60909.
- Protective device and distribution equipment short circuit breaking/rating capacity analysis.
- Simple protective device coordination (TCC’s).
- Arc flash incident energy analysis.
- Arc flash boundary distance.
The site received high voltage (11kV) power supply from Denby Pottery via their ring main unit to a transformer. However, since this is a Solar PV plant, power was also being generated and fed into the Denby Pottery electrical network.
Any instances where the 3-phase prospective short circuit current exceeded the breaking capacity of the protective devices were highlighted in the arc flash risk assessment report. Protective curves showing any instances of miscoordination were provided for the circuit protective devices.
Incident energy levels and arc flash boundary distances were listed for all equipment included in the scope of the study. This included the main LV feeder pillar as well as the isolation switch panels for all the inverters.
Incident energy hazard reduction analysis was then conducted and preferred options and order of magnitude of cost were given for the reduction of the incident energy where it was above 8 cal/cm2. Further to this, we also provided guidance on the “As Low as is Reasonably Practicable” (ALARP) requirements in line with UK Legislation to provide an indication of what might be expected to be invested to reduce and manage the risk from potential arc flash incidents.
We provided a Microsoft Teams video presentation of the Arc Flash Risk Assessment Report to Power Zero Energies Head of Solar Delivery and Solar Project Engineer, to assist in the understanding of the arc flash risk assessment study, its findings, the recommendations, and the proposed next steps to support the improvement and management of their arc flash risk.
United Kingdom/European Standard compliance arc flash labels were issued to Power Zero once site personnel approved the design, along with up-to-date single line drawings for the electrical distribution network that provided the Site Data, Prospective Short Circuit Current (Fault Study) and Arc Flash Study Analysis information.
