Measuring high currents with small current sensors

Modern current measurement trends in uninterruptible power supplies (UPS) and renewable energy systems is towards smaller physical size, higher current ranges, faster response times and lower cost. The simplicity of open-loop sensors makes them an attractive solution for attaining these objectives. This article discusses three new families of sensors which allow the nominal current to […]

Power and water: Leliefontein pump-as-turbine station

Originally intended to be a booster station, Leliefontein’s location proved ideal for the establishment of a mini hydro-electric power station. The project, a marriage between the civil, mechanical and electrical engineering disciplines, shows how municipalities can use low cost, off the shelf equipment to generate clean power in their existing infrastructure. Wellington is home to […]

Winding resistance testing of motors

Winding resistance measurements detect various faults in motors and transformers: shorted turns, loose connections, broken strands and malfunctioning tap changer mechanisms. Winding resistance measurements detect problems in motors which other tests may not find. These problems include partial or fully shorted coils, poor crimps or connections, imbalance between phases (improper turns on phases) and incorrect […]

Understanding the basics of power measurement theory

Electrical power applications are changing rapidly which means the load on the electric network is changing: more harmonics and more risk of unbalance. This so-called “bad” power costs money and wastes energy. This article provides some basic theory to understand what is happening with today’s electrical applications. Apparent power To understand the relation between active […]