3 Safety-Related Functions 11.03
3.5 Safely-reduced speed (SG)
© Siemens AG 2003 All Rights Reserved
3-92 SINUMERIK 840D/SIMODRIVE 611 digital SINUMERIK Safety Integrated (FBSI) - Edition 11.03
3.5 Safely-reduced speed (SG)
The purpose of the SG function is to safely monitor the load-side speed of an
axis or spindle.
The actual speed of the axis/spindle is compared with the speed limit value
selected via SGEs. The speed limit values are defined in the following machine
data.
For 840D MD 36931: $MA_SAFE_VELO_LIMIT
[n]
For 611 digital MD 1331: $MD_SAFE_VELO_LIMIT[n]
The speed limit values for SG1, SG2, SG3 or SG4 allow various
applications/operating states on the machine to be monitored. The safely-
reduced speed function can therefore be used to implement protection for the
operating personnel and machine in the setting-up mode or in automatic
operation.
!
Important
The user must be careful to select the correct gear ratio for axes with selector
gearbox.
The features of the SG function are as follows:
• Safe monitoring of load-side speed limit values
• Monitoring limit values are adapted to various operating states (e.g. test,
setting-up, automatic modes)
• Configurable stop response after the SG responds.
The following prerequisites must be fulfilled (refer to Chapter 2.8, "System
requirements"):
• Option and functions must be enabled in the axis-specific machine data
• The SGEs "SBH/SG de-selection" and "SBH de-selection" must be
configured.
The requirements regarding speeds and velocities that are stipulated for
individual processes (e.g. milling, turning, grinding, etc.) vary depending on
standards (e.g. ISO 11161) or activities relating to standards (e.g. CEN
TC 143). As an example, standards could be stipulated for the setting-up mode
as follows:
"Safely-reduced speed" at 2 m/min for feed drives or
50 rev/min for spindle drives or standstill within 2 revolutions.
The machine manufacturer must parameterize SI in such a way as to ensure
full compliance with the EC Machinery Directive. The relevant standards
provide the necessary guidelines.
Quantities that influence the parameterization include, e.g. the drive dynamic
response, the set parameter with its delay times, electrical and mechanical
ratios and all of the mechanical properties and characteristics. The
interrelationships between the drive dynamic response and internal delay times
of SI are shown in Fig. 3-7 "Timing when exceeding the limit value for SG".
Description
Features of the
function
Prerequisites
Specifying velocities
and speeds
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