Traversing Direction For The Brake Test - Siemens SINUMERIK 840D sl Function Manual

Connecting sensors and actuators
8.6 Safe Brake Test (SBT)
To ensure that the brake test functions without any errors, it should be checked as to whether
the required test torque in MD36966 $MA_SAFE_BRAKETEST_TORQUE is not prevented
from being generated due to the fact that torque limits are effective in the drive. For details on
this, please see SINAMICS List Manual, e.g. function charts 5610 and 5620.
For instance, the selectable torque limits from p1520/p1521 and p1522/p1523 may not be set
so low that the required torque cannot be established for the brake test. When required, p1520/
p1521 or p2003 should be adapted. When making a change to p2003, machine data 36966
should be re-determined.
Further, e.g. the following parameters can also have a limiting effect:
● p1530/p1531 (power limit, motoring/regenerating)
● p0640 (current limit)
● p0326 (motor stall torque correction factor)
The following points should be taken into consideration when calculating the test torque:
● The matching torque corresponding to the current limit of the power unit (p0640) is:
p1520 = p640 * p316
p1521 = -(p640 * p316)
p2003= p640*p316
● The content of parameter p1520/1521 is greater than or equal to the content of parameter
p2003.
● Brake test torque calculation:
Brake test torque = value from r1509 * 1.3, or
Brake test torque = input from the mechanical system * 1.3
8.6.4

Traversing direction for the brake test

The brake test must always be started when the axis is at a standstill. The direction in which
the drive produces its force is specified by the PLC using the direction specified by the
traversing motion of FC18. For a brake test, the motor should apply a force to the brake that
is applied in addition to the force due to weight. The target of this traversing motion must be
able to be reached without incurring any potential hazard (sufficient clearance to end stops)
for the case that the brake cannot provide the necessary force. As part of the application, the
position can be interrogated using conventional cams (not safety cams, as this is not a safety-
related function) that then define the traversing direction of the axis via FC18 during the braking
test. If a brake test is executed against the force due to weight, in spite of the closed brake,
the motor must generate a torque corresponding to the force due to weight and the test torque.
Note when using MD36968 $MA_SAFE_BRAKETEST_CONTROL, bit 0 = 0:
If a traversing direction is selected that opposes the force due to the weight, Alarm "20097 axis
%1 incorrect direction braking test" is initiated if the actual torque, when selecting the brake
test, deviates by more than 7.5% of MD36966 $$MA_SAFE_BRAKETEST_TORQUE from
drive parameter p1532. This alarm indicates that the brake test was executed with a torque
that was incorrect by more than 15%. In principle, automatically determining the available load
torque using MD36968 $MA_SAFE_BRAKETEST_CONTROL, bit 0 = 1 is the preferred
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Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated