Baumuller BUM64A, Руководство пользователя

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Safety categories
Manual Single Power Unit BUM64S/A/F
Document no.: 5.01056.03
Baumüller Nürnberg Electronic GmbH & Co. KG
108
of 118
The power supply to the windings of the motor is reached at a stoppage by inhibiting the power
semiconductor. As semiconductors possibly can fail or be started, because of electromagnetic
disturbances, the behaviour of the shut down drive has to be considered if such a fault scenario
arises. The fail or "accidental" turning on of a single or of more power semiconductors at the
same DC-link pole does not lead to an uncontrolled starting, as no current flow is accomplished.
Not until additionally a further power semiconductor is enabled at another DC-link pole, current
is able to flow through the motor. If, thereby the DC-link is directly short-circuited, the fuses
which are upstreamed to the converter are tripped, the motor doesn’t start. If the DC-link is
"short-circuited" over a winding of the motor, a magnetic field can be set up in the motor. If it is
an asynchronous motor, then the generated d. c. magnetic properties cannot cause a lurch of
the inductor. By the permanent-magnetic synchronous motor the inductor will rotate into a notch
position. The therewith angular movement which is covered is dependable of the inductor’s po-
sition and the number of pole pairs of the motor. It amounts to maximal 180°/number of pole
pairs. Subsequently the enabled DC-link operates like a brake, this means after the ending of
the lurching movement the drive is in a blocked condition. A starting of the drive is impossible.
If a machine with a synchronous motor is planned, the possible sudden movement must be con-
sidered, because it can lead to a dangerous movement. Therefore the machinist must carry out
a safety evaluation for the residual movement.
The function of the safety relay is limited to the prevention of an unexpected starting. The switch-
ing of the safety relay, while the inductor of the motor is rotating, causes an uncontrolled "coast-
ing" of the machine, a braking with help of the converter is not possible anymore.
Turning off the safety relay has no isolation from the supply system as a consequence. There-
fore, mains potential can be both at the converter and at the motor. The protection against elec-
tric hazards has to be therefore saved with other means (for example master switches) when
maintaining, servicing or repairing electrical components of the drive system.
E.2 Safety categories
Dependant of the possible hazards (these are rated due to the consideration of the severity of
the injuries, the frequency of the length of stay within the hazard area and possibilities in order
to prevent hazards) security relevant components of machines have to meet certain safety cri-
teria. The requirements to safety-based parts are divided into five categories in the standard EN
954-1.
In category B basic demands, in 1 additionally safety-technical proved components and princi-
ples are claimed. In category 2 an error between inspection intervals can lead to a loss of the
safety function.
Category 3 accords to the level “the single-error-certainty to recognize errors partially”. The
safety-relevant components must be in such a way, that a single error doesn´t lead to a loss of
WARNING
The following may occur , if you do not observe this warning information:
m serious personal injury m death
The hazard is: electricity. Both on the motor and at the unit there can be mains voltage al-
though safety relay is switched off.
If required, switch the appliance off-circuit like an appliance without a safety relay - the safety
relay does not switch the appliance and the motor
off- circuit !