**How D.C. to A.C. Inverters Work**
Traditionally generation of electricity has involved rotating machines to produce alternating sinusoidal voltage and current (a.c. systems). With the development...

**Resistors**
Resistors are electronic components that oppose the flow of current. Manufactured in various types and ranges they have a wide application to electronics...

**ABB Technical Guides - Motor Operation**
ABB has produced a range of technical guides that offer concise explanations of the major technologies and technical issues in low voltage AC drives. ...

**Star-Delta Motor Starting - Performance**
Many questions sent in to the site are in connection with motor starting and in particular star-delta. For all but the simplest application, there is...

**Control Theory**
Control theory looks at how systems work and are controlled from a mathematical view. This note gives a brief introduction to some of the concepts – more...

**IEC 60287 Current Capacity of Cables - An Introduction**
IEC 60287 "Calculation of the continuous current rating of cables (100% load factor)" is the International Standard which defines the procedures and equations...

**Tips for a better Low Voltage Protection Discrimination Study**
Carrying out a protection system discrimination study is critical to ensure the correct functioning of the electrical system in the event of faults. ...

**Generation of a Sine Wave**
A fundamental concept behind the operation of alternating current systems is that voltage and current waveforms will be sinusoidal – a Sine Wave. This...

**Power Factor**
Power factor is the ratio between the real power (P in kW) and apparent power (S in kVA) drawn by an electrical load. The reactive power (Q in kVAr)...

**Fault Calculation - Per Unit System**
Per unit fault calculations is a method whereby system impedances and quantities are normalised across different voltage levels to a common base. By removing...