Issue link: https://fhpublishing.uberflip.com/i/1173186
To estimate the resources neces- sary to satisfy the DNOs' require- ment for monitoring and control To examine the security overhead required for smart grid applica- tions To de ne the scale of any future deployment To increase awareness of the im- portance of dedicated spectrum for safer power utilities To prepare documentation for input to Ofcom on spectrum requirements for utilities. When deploying any radio com- munication system such as private LTE in critical infrastructure ap- plications, access to licensed radio spectrum is crucial to guarantee the reliability of operation. The over- head tra• c required to secure any connection will be quanti ed, and the compliance with the IEC 62351 considered. To be able to determine the bandwidth requirements of the secondary substation of the future, current and future applications such as number of terminals, nodes and modems in each secondary substation along with the type of services and locations (rural/ urban) per substation are needed. Each application and service will also require a security overhead, for example through IEC 62351. Such overhead tra• c will aŠ ect the transmission rate of the terminal, which in turn aŠ ects the band- width and the required spectrum. Any chosen bandwidth should take into account the future updates in devices fed from the secondary substation such as EV charging points and battery storage. The question of whether the current rec- ommended spectrum of 1.4 MHz or even 2x3MHz can meet the current and future utility requirements will be addressed. The ongoing activities at PNDC will further consider the recent concerns from the National Cyber Security Centre and the DNOs on the security of future communica- tion for power utilities, as well as requesting inputs from DNOs and vendors on managing the available spectrum and reducing the poten- tial to lose power through enabling reliable communication technol- ogy. In addition to sharing the main inputs and test results with the spectrum regulator in the UK. NETWORK / 25 / OCTOBER 2019 Damon Mount, UK & Southern Africa sales manager at Megger, discusses safety and accuracy when testing circuit breakers. When a circuit breaker requires maintenance it needs to be isolated and grounded on both sides for safety. This can distort the test readings but removing the ground creates a safety hazard. Test instruments with DualGround capability make fast and accurate circuit breaker testing possible with both sides of the circuit breaker grounded. With DualGround measurements, engineers and technicians are protected against receiving dangerous shocks from voltages induced in the breaker, by current fl ow in nearby live conductors. This is critically important in the substation environment. It has been possible to measure timing with both sides of the circuit breaker grounded with dynamic resistance measurement (DRM) techniques, but the results are not always consistent and reliable. Dynamic capacitance measurement (DCM) technology is able to produce dependable timing results safely on all types of circuit breaker including GIS. The test confi guration for DCM testing is identical with that used for DRM measurements but, instead of looking at resistance changes in the main contact circuit during the operation of the breaker, DCM treats the contact assembly as a variable capacitor. As the breaker operates, the distance between the fi xed and moving contacts changes, which means that the capacitance between them also changes. DCM evaluates these capacitance changes and uses them to provide accurate and repeatable timing measurements. This method signifi cantly increases safety and accuracy and reduces testing time, since it is no longer necessary to remove one of the ground leads before making a measurement and reattaching it afterwards. For further information email: info@megger.com I N D U S T RY I N S I G H T Testing circuit breakers safely