What is ESD? Electrostatic Discharge (ESD) means the compensation of big differences in potential that causes high voltage pulses. This voltage pulse can cause damages or even destroy electronic components.
Potential differences often result from friction or contact and separation of items. By this a human can be charged up to 30.000 Volts. The electrostatic discharge can only be felt by a person from 2.000 Volt on as a small electric shock. However electrostatic sensitive devices can be harmed by a blocking voltage of 5 – 30 V. Therefore while working with electrostatic sensitive devices actions have to be taken to reduce electrical charges reliable and prevent the
occurrence of quick discharge.
Actions against static discharge are described in the EN 61340-5-1 standard. An effective grounding of persons by using ESD footwear serves to protect sensitive devices by frequently discharging the human body.
ESD shoes are made to discharge the electrostatic charge through the ground to the earth potential. The resistance of the system Person-Shoe-Ground shall be below 35 MOhm according to EN 61340-5-1 (verification). The qualification of the ESD footwear according to EN 61340-4-3 is measured in relation to the climate class 1 (12% RH), 2 (25% RH) and 3 (50% RH).
According to EN 61340-4-3 the shoe is preconditioned adequately and measured filled with a defined quantity of metal balls on a metal plate. Here the resistance shall be below 100 MOhm.
In practice the discharge capacity of ESD footwear is not only highly depending on the climatic environment (humidity and temperature) but also on factors like contamination and condition of the flooring as well as the electrical resistance of the person’s body. ESD representatives of a company have to check frequently if the implemented ESD products still work in a proper way. Where ESD footwear is worn the resistance of the flooring should not influence the functionality of the ESD shoes. The implementation of “walking tests” helps to validate the functionality of the system Person-Shoe-Flooring.
WARNING: ESD shoes are not suitable for electricians or while working on sources with any electric voltage.
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