
B-63494EN/02 1.OVERVIEW
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1.2 DEFINITION OF TERMS
1.2.1 General Definition of Terms
Reliability and safety
Reliability and safety are defined by EN292-1 as follows:
Term Definition
Reliability Capability of a machine, machine component, or
equipment to perform its required function under a
specified condition for a specified period
Safety Capability of a machine to perform its function without
injuring the health under a condition of use for an
intended purpose specified in the operator's manual and
allow its transportation, installation, adjustment,
maintenance, disassembly, and disposal
1.2.2 Definition of Terms Related to the Safety Function
Safe-related I/O signal
Safe-related I/O signals are input/output signals monitored by two
systems. These signals are valid for each feed axis and spindle with a
built-in safety function, and are used with each monitoring system.
Example: Protection door state signal
Safe stop
When a safe stop occurs, power to the drive section is shut off. The
drive section can generate neither a torque nor dangerous operation.
The following are measures for incorporating the safe stop feature:
Contactor between the line and drive system (line contactor)
Contactor between the power section and drive motor (motor
contactor)
If an external force is applied (such as a force applied onto a vertical
axis), an additional measure (such as a mechanical brake) must be
securely implemented to protect against such a force.
Safety limitation speed
When the drive system has reached a specified limitation speed, a
transition is made to the safe stop state.
A measure must be implemented to prevent a set limitation speed from
being changed by an unauthorized person.
Safe machine position
When the drive system has reached a specified positional limit, a
transition is made to the safe stop state. When a positional limit is set,
a maximum move distance traveled until a stop occurs must be
considered. A measure must be implemented to prevent a set
positional limit from being changed by an unauthorized person.