Siemens SIMOCODE pro C System Manual page 392

Glossary
Protection functions
The protection functions
● Overload protection
● Unbalance protection
● Stalled rotor protection
● Thermistor protection
● Dry-running protection
operate alongside motor control "at a higher level in the background." They can be active or
not, according to the control function selected.
Protective Extra Low Voltage (PELV)
Protective measure against electric shock (formerly referred to as "protective extra low
voltage with safe isolation").
In contrast to an SELV circuit, live parts and exposed conductive parts of the equipment may
be grounded and connected to the protective conductor. Safe isolation means that the
primary circuit of the transformer must be separated from the secondary circuit by double or
reinforced insulation. PELV is used whenever operational reasons dictate that live
conductors of the low voltage or bodies of the equipment must be grounded. This is the
case, for instance, if equipotential bonding is necessary to prevent sparking in containers or
hazardous areas. However, owing to the chassis ground, dangerous leakage currents can
flow through the body regardless of the low voltage if a fault occurs in the higher-level power
system.
Protocol data unit (PDU)
Consists of function code and the data
Record
Record.
RT communication
As a motor management system, SIMOCODE pro V PN does not have any time-critical
communication functions itself but it does support the PROFINET hardware RT used. The
integrated 2-port switch is therefore used to forward RT data.
SELV
Safety extra low voltage Low electric voltage that offers significant protection against electric
shock due to its low value and insulation. For certain requirements, the highest voltage must
be defined below 50 V AC or 120 V smoothed DC, especially if direct contact with live parts
is permissible. At a nominal voltage of 120 V, the greatest peak value in a smoothed DC
system is 140 V, and at a nominal voltage of 60 V it is 70 C.
Use of power supply units according to IEC 60536, protection class III (SELV or PELV):
392
System Manual, 05/2019, A5E40507475002A/RS-AD/004
SIMOCODE pro