Four customized Sine wave filters are now in operation at a customer in the mining industry in northern Sweden. Granitor Systems was commissioned to deliver a container solution for power distribution, where Tramo delivered Sine wave filters as part of the system. Sine wave filters supplied are used in pumps driven by frequency controlled (VFD) motors. High demands in this application led us to develop a customized solution.

Power quality problems in frequency controlled motors can’t be ignored

Voltage conversion with converters and frequency controlled motors can affect power quality, leading to bearing currents, voltage peaks and insulation failures. These problems shorten both motor life and service intervals. Frequency controlled motors are used in countless applications worldwide, making this a problem that can’t be ignored.

Why is a starting current limiter needed?

When a transformer is energized, an inrush current occurs, which can cause a very high current spike for a short period of time. The magnetizing current can then be 10-20 times greater than the rated current of the transformer. This can cause several problems:

– Fuses or earth leakage breakers tripping
– Heavy load on switches and contactors
– Mechanical hum or stress in the transformer core
– Unnecessary wear on electrical installations

High starting currents may force you to choose a larger main fuse, which means a more expensive electricity subscription. In addition, power spikes can affect costs if you are on a power tariff. With a starting current limiter, the risk of fuses tripping is reduced and you can keep a smaller main fuse, saving money.