Lenze E94AYAD - SM300 - Manual (Page 9)

Safety engineering
Basics
Hazard and risk analysis
1
1.1
1.1.7

1.1-5 EDS94AYAD EN 2.2
Incase of a short-circuit of two power transistors a residual movement of the
motor of up to 180 °/number of pole pairs may occur! (Example: 4-pole
motor ⇒residual movement max. 180 °/2 = 90 °)
This residual movement must be considered in the risk analysis, e.g. safe
torque off for main spindle drives.
1.1.7 Hazard and risk analysis
This documentation can only accentuate the need for a hazard analysis. The
user of drive-based safety must concentrate on dealing with the standards
and legal position.
Before putting a machine into circulation, the manufacturer of the machine
must carry out a hazard analysis according to the Machinery Directive
89/392/EEC to find out the hazards related to the application of the
machine. To achieve a level of safety as high as possible the Machinery
Directive contains three principles:
ƒ Removing or minimising the hazards by the construction itself.
ƒ Taking the protective measures required against hazards that cannot
be removed.
ƒ Documentation of the existing residual risks and training of the user
regarding these risks.
The execution of the hazard analysis is specified in EN 1050, guidelines for
risk assessment. The result of the hazard analysis determines the category
of safety-based control modes according to EN 954-1 which the
safety-oriented parts of the machine control must comply with.
1.1.8 Standards
Safety regulations are confirmed by laws and other governmental
guidelines and measures and the prevailing opinion among experts, e.g. by
technical regulations.
The regulations and rules to be applied must be observed in accordance with
the application.
1.1.9 Overview of sensors
Passive sensors are two-channel switching elements with contacts. The
connecting cables and the sensor function must be monitored.
The contacts must switch simultaneously. Nevertheless, safety functions
will be activated as soon as at least one channel is switched.
The switches must be wired according to the closed-circuit principle.
Examples of passive sensors:
ƒ Door contact switch
ƒ Emergency-off control units
Residual hazards
Passive sensors