In commercial, industrial, and medical electrical devices, suppression of electromagnetic interference (EMI) (sometimes called radio-frequency interference (RFI)) is a critical design consideration. While there are many possible sources for EMI / RFI noise that might cause problems for electrical circuits, the power source to the circuit is of particular concern. Because all electrical circuits need power, it is necessary for designers to eliminate or filter out as much noise as possible from that power supply.
This is easier said than done. EMI filtering is more difficult, and more important, for higher current/higher power lines. KEMET’s GTX filters and their nanocrystalline features provide a compact, lightweight solution to this pervasive design problem.
KEMET makes many products for EMI / RFI filtering. One of the most common and effective types of EMI filters are common mode chokes. These devices utilize conductor windings coupled together via a ferrite core. The KEMET SCF coils, for example, are common mode chokes with a wide variety of characteristics. These toroidal coils are designed with nanocrystalline metal cores and are useful in various noise countermeasure applications.
Figure 1: KEMET’s SCF common mode chokes
An advancement on this technology, the KEMET GTX plastic case filters cover single-phase EMC requirements with a wide variety of EMI suppression characteristics. Also using a nanocrystalline core material, these filters achieve excellent attenuation characteristics in a compact size. In addition, they also incorporate six different combinations of Y capacitors that can be selected to support various inverter topologies. These filters are compact and lightweight due to their high mechanical density.
Figure 2: KEMET’s GTX Plastic Box Single-Phase EMI filters
Suitable for commercial, industrial and medical applications, the GTX EMI / RFI filters support single-phase voltages up to 250 VAC, and are rated for operational current from 6 A to 30 A. All of this, plus the integrated Y capacitors, comes in a compact 75 mm x 44 mm package.
The key to the great performance of the GTX filters is the nanocrystalline material used as the magnetic core material. The nanocrystal soft magnetic material is a new type of soft magnetic material that originated 1988. It has only recently begun to be used in various applications such as choke coils and transformers for power electronics. Since it has excellent characteristics compared to conventional materials, these parts can be significantly reduced in size, contributing to the miniaturization of electronic devices.
Ferrite materials with higher magnetic permeability are effective in the lower frequency range, while those with lower magnetic permeability are effective in the higher frequency range. Metal nanocrystal materials, however, are effective throughout a broadband frequency range, in low as well as high frequencies.
Figure 3: Relationship between the magnetic permeability of each material and its effective frequency range
The many key features of GTX filters are summarized in the table below:
KEMET’s GTX EMI-RFI filters are suitable for many different end products across many industries; below are just a few examples in the different segments.
The GTX series provides a solution for suppressing electromagnetic conductive noise on single-phase voltage lines in a compact and lightweight design.
Figure 4: Internal circuit diagram of GTX filters
High attenuation performance can be targeted at specific noise frequencies by selecting from 30 product variants according to rated current and desired Y-capacitor pattern.
Figure 5: Example attenuation chart for the GTX-2060*** (6 A rank)
The GTX-2060-***, for example, is rated at 6 A and can be selected in a variety of Y capacitor configurations. In an application where a 6 A rating is desired, the YXX variant would see peak attenuation at approximately 500 kHz, the Y22 at approximately 1 MHz, the Y0X at approximately 10 MHz, and so on. Each different current rank comes with its own attenuation vs frequency chart for the various Y capacitor configurations.
The GTX is packaged in a housing with screw terminals to provide ease and flexibility when wiring.
KEMET’s GTX EMI-RFI filters provide suppression for conduction noise on single-phase voltage lines. Meeting EMC requirements using nanocrystalline core material, these filters achieve excellent attenuation characteristics in a compact plastic case. The nanocrystalline core along with the integrated Y capacitor combinations provide flexibility for any application.
The KEMET GTX filters will are available in the Americas, Europe, and Asia since November 19th, 2020.