Baumuller b maxx BM4400, Instruction Handbook Manual

Page: 327 / 360

327
of 358
Instruction handbook b maXX BM4400, BM4600, BM4700
Document No.: 5.12008.07
A
PPENDIX
C - S
AFE STOP
In this chapter the safety function „Safe stop“ is described for b maXX 4000 . This safety function
is valid for BM4400, BM4600 and BM4700.
C.1 Methods to avoid an unexpected starting
In order to avoid danger for persons, for example operators, service- and maintenance techni-
cians, the machine must be kept in a safe state (safe stop), while taking action in the dangerous
area of the machine. Therefore a reliable prevention of an unexpected starting is required (Ma-
chine Directive 06/42/EG, attachment I, 1.2.4; EN ISO 12100-1; EN 60204-1, 5.4; EN 62061;
EN 61800-5-2). Unexpected starting causes a risk for persons, because of its unexpected oc-
currence (EN 292-1).
Besides the transmission of the enable state into the operating state of the machine, the unex-
pected starting of the machine must be considered. This is the transmission from the safe stop
into an unsafe moving. Unexpected starting refers to an interruption of the control loop of the
machine. The drive achieves the maximum speed at maximum acceleration, due to its control.
The operator will not be able to leave the danger area or to remove his hand from the danger
area. Therefore, the drive must be kept safe „off-position“ with opened and electrical interlocked
safety devices. The motor must be in torqueless state. Thus, the motor cannot generate a dan-
gerous movement.
The prevention of an unexpected starting of the machine is reached with electrical separated
safety devices, e.g. contactors.
This is not state of the art, because the conventional operation in the power circuit of the drive
may cause unnecessary wear on the switching element and long response times in the ma-
chine.
Some machine types are not electrically isolated between the electrical connection of the drive
and the power supply. If, for example, a drive supplied by a power converter is stopped and
started again very often and in short intervals. The constant discharging and recharging of the
DC link represents a great stress for the parts and leads to disturbing delays and early failures
of the parts.
The integration of the protection function is more efficient for preventing an unexpected starting
directly into the inverter. Here, the drive is not isolated from the power supply. However, the
commutation of the power semiconductors is safety prevented in the inverter.
In Baumüller inverters of the b maXX 4000, this occurs by the safety relay, which switches the
power supply off for the IGBT control.