Manufacturers of electrical and electronic equipment realize the need for product quality in order to maintain global competitiveness. Ensuring product quality invariably implies testing products for use with different and adverse power conditions that may exist. Unusual voltage and frequency combinations are common in many parts of the world and clean reliable AC power is not always available. To ensure safe and reliable operation of AC powered equipment and instrumentation, world power testing is now a requirement. AC power sources are available in many forms, offering a wide range of capabilities and features.