4.1.3.2 Earthing concepts
4.1.3.2.1 Protective Earth
An earthing system (UK and IEC) or grounding system (US) affects the system’s safety and the
electromagnetic compatibility (EMC).
Protective earthing is a type of earth used to protect people and animals from electric shocks and is effective
in the event of a fault.
Protective earthing ensures on one hand that the user is at the same electrical potential as the device
housing and on the other hand lets the fuse blow out of a short between phase and ground.
This protects users from electrical shocks when a piece of electric equipment has an insulation failure.
When an insulation failure occurs, the current can pass through the earthing cable path that is more
conductive than the human body. The images below show the safe and dangerous conditions with and
without PE.
4.1.3.2.2 Functional Earth
Functional earth or functional ground is essential to have a trouble-free operation.
Possible consequence when functional earth (FE) is not considered:
Damage to electronic devices by electrostatic discharge is possible
EMC issues such as ground loops, random system behavior
Incorrect reading of the feedback devices that can cause control problems
Communication problems and loss of data or synchronization.
Interference to surrounding circuits near the servo drive system.
Compliance with Electromagnetic Compatibility (EMC) standards and directives may not be given.
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