A closer look at soft starters and VFDs, their advantages, disadvantages and applications. A large starting current may be required (typically 5 – 7 x FLC) when accelerating an AC motor to full speed using a full voltage connection. Additionally, the torque of the AC motor is mostly uncontrolled and can shock the connected equipment, […]
This article considers the technologies and topologies of MV drives, their advantages disadvantages, and their impact on the quality of energy on the mains and motor sides. Advancements in semiconductor devices such as insulated gate bipolar transistors (IGBTs) allow medium voltage (MV) drives to be used increasingly to conserve energy, increase productivity and improve product […]
Motor manufacturers are reporting an increase in damage to bearings and connected equipment caused by electrical current flow. The failure rate of bearings and connected equipment due to current flow is thought to be small relative to the total number of motors sold, but the frequency of failures is growing as more users install pulse-width […]
Equipment damage, arc flash hazards and unplanned outages are greatly reduced when overcurrent protection devices are operated and maintained properly. Business owners and facility management teams are increasingly concerned with their ability to keep their equipment working at peak performances. This leaves them with the task of managing the myriad maintenance challenges which include extending […]
Why transformer-free uninterrupted power supplies (UPSs) meet the vast majority of power supply design requirements. The first double-conversion UPSs where born in the 1970s. The semiconductors available at the time were bigger and less compatible with voltage levels than they are today. As a consequence, UPS systems needed transformers to step up the voltage of […]
The miniature circuit breaker (MCB) has replaced the fuse in incoming distribution boards since the 1960s, so increasing incoming protection by making it impossible to bypass blown fuses with nails or wire – a frequent and dangerous practice. Functioning of the MCB An MCB is a mechanical switching device able to make, carry and break […]
This article discusses a break-through in the field of electrical protection and identifies critical application areas where arc fault detection devices enhance safety. Although the terms, “arc fault” and “arc flash” look and sound similar, they are very different and are often confused. Electric arc faults occur when an electric arc current is generated in […]
Examples of were reclosers provide integrated solutions to improving the continuity of supply after the occurrence of a phase-to-earth fault. The advent of the microprocessor protection relay within recloser controllers has allowed the introduction of a significant number of new protection features and functionalities. In parallel with these enhancements, the recloser has transformed into an […]
The importance of reliable power connections in protecting electrical installations from the risk of electrical fires. Power connection safety and reliability is not just advisable, it’s essential. Reliable connections are critical in terms of protecting installations against electrical fires, which can inadvertently start as a result of poor or loose connections. A number of factors […]
Most power transformers use oil as an insulating and cooling medium but, where substations are located in restricted spaces, gas is used for this purpose. Gas insulated switchgear is commonly used in substations and the development of gas insulated transformers allows complete integration of substation equipment with resultant space and cost savings. Gas insulated transformers […]
