Editorial Columns

PPC Insulators

Dielectric Strength & Air Density

While a number of atmospheric parameters affect the dielectric strength of external insulation, relative air density (δ) and absolute humidity are considered the most significant. Here, the focus is on the former, which plays a key role in developing... Read More

Progress Standardizing Recommended Creepage in DC

Today’s demand for integrating renewables into energy supply has made HVDC transmission a much more interesting option than in the past. This is triggered by factors such as that HVDC systems may be less expensive in terms of required equipment investment... Read More

Resistivity Measurement of Conductive Silicones

Modern cable accessories and connectors are being manufactured using a broad range of silicone elastomers and auxiliary materials – from fluids to gels to pastes. Those elastomers that contain electrically conductive fillers (generally referred to as... Read More

Importance of Line Entrance Arresters

At most air-insulated substations, the arrester mounted at the transformer is close enough to other equipment to provide effective protection from flashover. However this applies only if the breakers are closed. If a breaker is open, the insulators on its... Read More

External Insulation Under Composite AC Plus DC Voltages

Growing interest in parallel routing of AC and DC circuits on the same towers of what are referred to as ‘hybrid overhead lines’ could cause both AC and DC voltage components (known as composite voltages) to appear on line insulators. Up to now, knowledge... Read More

Understanding Energy Rating of Distribution Arresters

“What is the kJ/kV Uc rating of a Class 1, 10 kA arrester? This type of question has often been asked when it comes to distribution arresters. Yet finding an answer was never easy since these arresters (formerly referred to as Class 1) never had energy... Read More

Simulation Versus Laboratory Testing

The transmission and distribution sector faces a constant challenge to deliver reliable as well as affordable electrical power. Hence, it is always looking how best to improve on both. Standards-based certification of equipment has traditionally been viewed... Read More