Electromagnetic interference examples of telecommunications system in the frequency range from 2kHz to 150kHz

Recently malfunctions of telecommunication installations caused by switching noises of electric equipment or devices have been increasing. The switching noises usually have low frequencies between 2 kHz and 150 kHz. This paper shows some electric interference examples of telecommunication system cause by ac mains noises in frequency range from 2 kHz to 150 kHz. This paper also shows a necessity of emission requirements below 150 kHz for all equipment against EMC problems.