LEXIUM MHDA1004, Руководство пользователя

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Chapter 5 System Operation
84
890 USE 120 00
Description of the restart lock -AS-
(MHDA
••••
A00 drives only)
Advantages of
the restart lock A frequently required application task is the protection of personnel against the
restarting of drives. This can not be achieved by an electronic inhibit, but must be
implemented with mechanical elements (positively driven relay contacts).
To get round this problem, up to now either the main contactor in the mains supply
line was switched off, or another contactor was used to disconnect the motor from
the servo amplifier.
The disadvantages of this method are :
l
the DC-link has to be charged up again at restart
l
wear on the contacts of the contactors, caused by switching under load
l
extensive wiring required, with additional switching components
The restart lock -AS- avoids these disadvantages. A safety relay in the servo
amplifier is activated either by the PLC or manually. Positively driven contacts
provide a safe disconnection of the amplifier, the setpoint input of the servo
amplifier is inhibited, and a signal is sent to the safety circuit.
Advantages of the restart lock -AS- :
l
the DC-link remains charged up, as long as the mains supply line remains
active
l
only low voltages are switched, so there is no contact wear
l
very little wiring is required
l
the functionality and the personnel safety when using the circuit
recommendations in this documentation have been approved by the trade
liability association.
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