Effects of voltage amplitude modulations on mechanical vibrations in low voltage transformers

With the increasing use of sophisticated controls and equipment the continuity, reliability, and quality of electrical service has become extremely crucial to many power users. Electrical systems are subject to a wide variety of power quality problems which can interrupt production processes, affect sensitive equipment, and cause downtime, scrap, and capacity losses. Momentary voltage fluctuations can involve different kinds of undesired phenomena on electrical machines. This paper examines the impact of voltage fluctuations on the mechanical vibrations in low voltage transformers, with an experimental approach. The experimental analysis has been carried out testing a three phase, 10 kVA, low-voltage transformer. The measuring system is an ad hoc system for the EMC low-frequency immunity testing that generates sinusoidal and rectangular amplitude modulations. The experimental results show that a few percent amplitude modulations can involve a critical behavior in terms of vibrations, in addition to the magnetostriction, and can induce mechanical resonance phenomena