Protective Extra-Low Voltage As Protection Against Electric Shock; Protection Against Dangerous Movements - Bosch Rexroth MAD Project Planning Manual

MAD / MAF Asynchronous Housing Motors
3.3.2

Protective extra-low voltage as protection against electric shock

3.3.3

Protection against dangerous movements

● Connect the protective conductors of the electric drive and control sys‐
tems always fix and continuously with the external supply network.
● Do a protective conductor connection with a minimum cross section ac‐
cording to the following table.
Cross-sectional area A of the live wires
A ≤ 16 mm²
25 mm² < A ≤ 50 mm²
50 mm² < A
Tab. 3-1: Minimum cross-section of protective conductor connection for motors
Protective extra-low voltage is used to allow connecting devices with basic in‐
sulation to extra-low voltage circuits.
On components of an electric drive and control system provided by Bosch
Rexroth, all connections and terminals with voltages up to 50 volts are PELV
("Protective Extra-Low Voltage") systems. It is allowed to connect devices
equipped with basic insulation (such as programming devices, PCs, note‐
books, display units) to these connections.
Danger to life, risk of injury by electric shock! High electrical voltage by incor‐
rect connection!
If extra-low voltage circuits of devices containing voltages and circuits of
more than 50 volts (e.g., the mains connection) are connected to Bosch
Rexroth products, the connected extra-low voltage circuits must comply with
the requirements for PELV ("Protective Extra-Low Voltage").
Dangerous movements can be caused by faulty control of connected motors.
Some common examples are:
● Improper or wrong wiring or cable connection
● Operator errors
● Wrong input of parameters before commissioning
● Malfunction of sensors and encoders
● Defective components
● Software or firmware errors
These errors can occur immediately after equipment is switched on or even
after an unspecified time of trouble-free operation.
The monitoring functions in the components of the electric drive and control
system will normally be sufficient to avoid malfunction in the connected
drives. Regarding personal safety, especially the danger of injury and/or
property damage, this alone cannot be relied upon to ensure complete safety.
Until the integrated monitoring functions become effective, it must be as‐
sumed in any case that faulty drive movements will occur. The extent of faulty
drive movements depends upon the type of control and the state of opera‐
tion.
Safety notes for electric drives and controls
Minimum cross-sectional area A
protective conductor
A
25 mm²
A / 2
R911295781_Edition 11 Bosch Rexroth AG
11/265
of the
PE