July 2013 3.8 Supply voltages in the HSCI system 227
The CC 6xxx controller unit is supplied by the X69 supply bus of the
HEIDENHAIN supply module and X74 (+5 V).
The signal ground is used for functional-equipotential bonding. The signal-
ground connections (B) of the HEIDENHAIN control components must be
connected to the central functional ground of the machine (minimum cross
section 6 mm
2
). The 0 V PLC and all of the protective-ground connections of
the HEIDENHAIN control components must be connected separately from the
signal-ground connections to the central protective ground (PE) of the machine
(minimum cross section 6 mm
2
). The central signal ground and the central
protective ground must be connected with each other for the machine! The
cross section of this conductor must be at least as large as the largest cross
section of the conductors for connecting the components used to protective
ground or functional ground.
The +24 V NC supply voltage (PELV system according to EN 50178) is
required to be safely separated voltage for the entire HSCI system and
must not be connected to the +24 V PLC supply voltage (ELV) of the
system.
Protective Extra Low Voltage (PELV) according to EN 61800-5-1 must be
complied with for the +24 V NC power supply of the machine.
VDE 0160/EN 50178 is to be observed for the +24 V NC voltage lines and
cable routing. Lines or cables for safely separated electric circuits thus
must have double or reinforced insulation between the wire and the
surface if they are routed without spatial separation from other cables
and lines.
Due to the structure of the PLC area in the HSCI system, the +24 V PLC
supply voltage is a voltage with basic insulation (ELV as per EN 61800-5-
1).
The 0 V signal of the NC power supply must be connected by a 6 mm
2
conductor to the machine's central functional ground (B).
The 0 V signal of the PLC power supply must be connected by a 6 mm
2
conductor to the machine's central protective ground (PE).
The line cross section of the +24 V NC power supply must be designed for
the power consumption of the connected devices. EN 60204-1 lists the
protection provided by line cross sections.
Minimum cross section of the +24 V NC power supply: 0.75 mm
2
The motor brakes are controlled by 24 V PLC voltage. The trigger circuit and
the brake itself are usually separated from the line power only by basic
insulation according to EN 618100-5-1 (also EN 50178). Also, other add-on
devices that are controlled by PLC circuits usually have only basic insulation
from the line power.
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