Supply Voltages In The Hsci System - HEIDENHAIN iTNC 530 HSCI Technical Manual

3.8 Supply voltages in the HSCI system

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Two separate 24 V power supplies must be used to supply the +24 V power to
the individual control components in the HSCI system: +24 V NC and +24 V PLC.
HEIDENHAIN recommends using the DC-link buffered PSL 13x for supplying
power to the HSCI components, see "PSL 13x low-voltage power supply unit"
on page 237.
If you are using the UEC 11x, the main computer and other NC components
are usually supplied via the 24 V power supply unit of the UEC (connection
X90). A PSL 130 is not necessary if the total current consumption of the NC
supply of all HSCI components does not exceed 3.5 A.
External PL assemblies with HSCI (e.g. the PL 6xxx or the PL in the UxC 11x)
consist of an HSCI part (bus module and logic) and a PLC part (PLC input/
output assemblies). Due to the topology of the HSCI system, the 24 V NC
voltage supplied to the HSCI part must comply with the requirements for
double basic insulation according to EN 50 178 (PELV). All other NC
components with HSCI interface (e.g. main computer and machine operating
panel) must also be supplied with 24 V NC voltage with double basic
insulation. The reason for the double basic insulation is electrical safety, e.g.
accessibility of connecting elements supplied with +24 V NC voltage.
PLC components, such as motor holding brakes and solenoid valves, usually
have simple basic insulation. The PLC part must therefore be powered by
another +24 V supply voltage. The two supply voltages must not be
connected to each other. The double basic insulation of the NC power supply
is removed through "mixed operation," i.e. +24 V NC voltage with double basic
insulation is connected to PLC components with simple basic insulation. This
is not permitted in an HSCI system.
The following components are powered by +24 V NC supply voltage:
MC 6xxx, MC 7xxx main computer unit or industrial PC

BF 2xx TFT visual display unit

MB 6xx or MB 7xx machine operating panel

TE 6xx or TE 7xx keyboard unit

Protective Extra Low Voltage (PELV) according to EN 61800-5-1 must be
complied with by the power supply unit for the +24 V NC supply voltage.
The following components are powered by +24 V PLC supply voltage:
PLB 6xxx input/output module

UxC 1xx input/output module

PLD-H digital plug-in module for PLB

PLA-H analog plug-in module for PLB

Motor holding brakes, further components in the PLC circuit

Note
HEIDENHAIN recommends also using a power supply unit complying with
Protective Extra Low Voltage (PELV) according to EN 61800-5-1 for the
+24 V PLC power supply, although the circuit has only ELV status. In
addition, HEIDENHAIN recommends connecting the 0 V PLC supply
voltage to protective earth (PE). This is not strictly required according to the
VDE standards. However, it provides additional safety in the event of
insulation failure in the PLC circuit.
HEIDENHAIN Technical Manual iTNC 530 HSCI