Siemens Simatic 6ES7 157-0AD81-0 A0 Series Manual page 174

Glossary
Ground
Ground refers to the entirety of all interconnected inactive parts of an equipment
that cannot possess a dangerous contact voltage, even in the event of a
malfunction.
Ground
The conductive mass of earth, the electrical potential of which can be set to zero
at any point.
Grounding
Grounding means connecting an electrically conductive component to ground by
means of a grounding system.
Ground terminal PE
Name of the connector on electrical equipment used in potentially explosive
areas to which the potential bonding system is connected.
Hazardous area
An area in which the atmosphere could become explosive (i.e. there is a
potential danger).
H System
System with high availability consisting of at least two central processing units or
two separate devices, e.g. PCs (master/reserve). The user program is processed
identically in the master and reserve PCs.
HW Config
Component of STEP 7 for configuring hardware.
Ignition protection type
This refers to the special measures taken with electrical equipment to prevent
the ignition of an explosive atmosphere.
Glossary-4
DP/PA Link and Y Link Bus Couplings
A5E00193841-01 1