Friwo : Leakage Current

29. January 2016

What is leakage current?
Leakage current is an unwanted electrical current in an electric circuit. In a correct operating electric circuit, it flows directly via protective conductor to earth (earth leakage current) or indirectly via conductive parts, such as housing, chassis or a person touching the housing (touch current).
Is leakage current dangerous?
Leakage current means a risk for the user. If a person touches a defect device, an extremely dangerous leakage current can flow to earth via that person - the person gets an 'electric shock'.
In addition to the danger to persons, a too high leakage current can lead to incorrect measurement values, if certain measurement instruments are run with such a power supply. Therefore, manufacturers of power supplies have to make sure that their products meet the requirements concerning leakage current and electromagnetic compatibility.

How high may a leakage current be?
To protect users and systems, the maximum allowed value of leakage current is regulated precisely. Standards like IEC 60950-1 for IT equipment, IEC 60601-1 for medical devices or IEC 60335-1 for household appliances defined which value limits and which measurement methods have to be observed. Depending on the unit type, a leakage current of up to 3.5 mA max. is allowed.

Usage of y-capacitors for EMC noise suppression and their impact on leakage current
Y-capacitors are often used for noise suppression in power supplies. They are auxiliary components in EMC noise suppression. But they have the disadvantage to cause leakage current. It is a basic principle: the bigger the value of the Y-capacitor is, the better is the noise suppression - but the higher becomes the leakage current.

FRIWO - an expert on leakage current and EMC
Based on 40 years of experience in the development and production of power supplies and chargers, FRIWO has built-up a leading expertise concerning minimum leakage current and EMC optimization. To this purpose, FRIWO has set-up own EMC test center at its headquarters in Ostbevern. As a result of this, smallest leakage current values of up to ≤ 10 µA have been achieved which are unrivalled in the market.

Problems with leakage current values or EMC of your power supply?
We will be please to help you if you give us a call: +49 (0)2532 / 810 or email us: sales(at)friwo.com
FRIWO Gerätebau GmbH - Von-Liebig-Str. 11 - 49346 Ostbevern - www.friwo.com