PPL Engineering Services | What We Do | 24.1 24.1 | Page 11

Electrical Selectivity Studies
Electrical Selectivity Studies ( selectivity in accordance with BS7671 ) are carried out to ensure adequate protection of electrical systems and the safety of service provision . This is to limit disruption to the electrical infrastructure by finely tuning protective devices to activate correctly , minimising business disruption and downtime in the event of fault or overload . Additionally , the Electricity at Work Regulations ( 1989 ) recommends reviewing selectivity every 5 years or following any significant change to the system .
Following a detailed on-site survey of the installed electrical equipment , you are provided with a written report accompanied with a system line diagram and a grading chart . Additionally , you will receive recommended protection device settings , which will provide an appropriate level of selectivity for fault and overload protection for the HV system characteristics .
A Typical Study Includes :
• A protection selectivity study of the HV system will include the first LV breaker from each transformer and all HV devices through to , and including , the District Network Operator protection device
• A fault flow level study on the HV system
• A load flow level study of the HV system
ENGINEERING SOLUTIONS UNDER ONE ROOF
11