KRF – EMI Filter
KRF filters use a combination of high frequency inductors and capacitors to reduce noise in the critical 150 kHz to 30 MHz frequency range. The inductors act as open circuits and the capacitors act as short circuits at high frequencies while allowing the lower power line frequencies to pass untouched.
KRF filters assist with cost effective compliance to EMC directives, in a compact, efficient, light-weight design. The high common mode and differential mode reduction in the critical 150 kHz to 30 MHz frequency range ensures that potential interference from AC drives is reduced or eliminated.
Non-Linear Loads
Non-linear loads can draw harmonic current from the source, resulting in harmful high frequency noise. There are many pieces of equipment that can generate EMI, variable frequency drives included. In the case of variable frequency drive, the electrical noise produced is primarily contained in the switching edges of the PWM controller. Increases in switching frequencies also increase the effective edge frequencies produces, thereby increasing the amount of electrical noise.
Filter Terminology
EMC Filter
The KRF is an EMC (Electro-Magnetic Compatibility) Filter which allows electrical and electronic equipment to operate without affecting or be affected by other electrical or electronic equipment.
EMI Filter
The KRF is also considered an EMI filter or RFI filter. The terms EMI and RFI are often used interchangeably. EMI (Electro-Magnetic Interference) is actually any frequency of electrical noise, whereas RFI (Radio Frequency Interference) is a specific subset of electrical noise on the EMI spectrum. Conducted EMI is unwanted high frequencies that ride on the AC wave form.
