Safe Brake Test (Sbt); Applications - Siemens Sinumerik 840D sl Function Manual

Connecting Sensors/Actuators

7.6 Safe Brake Test (SBT)

7.6 Safe Brake Test (SBT)
7.6.1

Applications

Axes and mechanical systems can drop due to gravity when the drives are
switched off. The function test of the brake mechanical system should be used for
all axes, which must be prevented from moving in an uncontrolled manner by a
holding brake. This test function is primarily intended for so--called "vertical axes".
The functionality is based on "travel to fixed stop" (FXS). Travel to fixed stop can
be individually parameterized to test the function of the mechanical braking
system. It is activated and deselected from the PLC. For further details on travel to
fixed stop, see /FB1/, F1.
The machine manufacturer can use his PLC user program to close the brake at a
suitable instant in time (guide value, every 8h, see Chapter 1.6.1 "Information
Sheets of the Employer's Liability Insurance Association") and to initiate that the
drive produces an additional force in addition to the weight of the axis. As long as
no fault has occurred, the brake can exert the necessary braking torque / the
necessary braking force and the axis will hardly move.
When an error occurs, the actual position value exits the parameterizable moni-
toring window. This prevents an axis from sagging. The function test of the brake
mechanical system is negatively acknowledged.
The brake test must always be started when the axis is at a standstill. The direc-
tion in which the drive produces its torque / its force is specified by the PLC using a
"traversing motion" via FC 18. The direction of travel should be selected so that the
motor applies force in the direction of the already existing force due to weight as a
result of the load. The target of this motion must be able to be reached without any
danger (no collision, sufficient distance to the end stops), if the brake cannot pro-
vide the necessary torque / force.
Note
When the brake test is active, no temperature compensation may be carried out.
Note
From software release 4.7 SP2, the brake test integrated in the drive can also be
used in conjunction with SINUMERIK Safety Integrated. You can find an
application example on the Internet at our "Industry Online Support":
7-324
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
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