180 HEIDENHAIN Technical Manual MANUALplus 620
3.6 Supply Voltages in the HSCI System
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 189.
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/out-
put 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 sup-
plied with 24 V NC voltage with double basic insulation. The reason for the
double basic insulation is electrical safety, e.g. accessibility of connecting ele-
ments 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 con-
nected 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 main computer unit or industrial PC
BF 2xx TFT visual display unit
MB 6xx machine operating panel
TE 6xx keyboard unit
Protective Extra Low Voltage (PELV) according to EN 61800-5-1 must be com-
plied 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
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.
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