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3.4 Special features
• Multiprocessor concept:
If a processor stops working, the other processor still continue monitoring its area.
If there is a control panel failure, the frequency converter automatically switches off
the drive if no inquiries are made via the interface for longer than 60 seconds.
• Interface concept:
The information transmission is monitored with an additional check sum.
• Hardware concept:
All safety related switches are break contacts. This also ensures that loose contacts
and cable rupture can be detected.
3.5 Brake resistor (R1)
• An overtemperature fuse protects the brake resistor against fire. If the braking
chopper has a short circuit, the brake resistor becomes hot due to the high current,
and the overtemperature fuse cuts off the frequency converter from the mains supply.
3.6 Motor / tacho system
• The motor is a three-phase asynchronous motor with two pairs of poles.
• A speed sensor (speedometer) which is screwed onto the motor receives
− the rotor code information and
− the speed information (6 pulses per revolution)
from the magnets of the tacho ring attached to the rotor.
• The control panel monitors and regulates the ACTUAL speed.
− Double safety:
In addition, the frequency converter has been programmed in
such a way that it is not possible to set a speed value which is
higher than the permissible rotor speed. The frequency
converter monitors the speed and switches off the drive at
excess speed (error message "ERROR 84").
• The control panel monitors the rotor standstill.
− The lid can only be opened when the control panel has detected standstill.
3.7 Lid lock
• Opening of the lid lock is prevented by a latch. The lid lock can only be opened when
the relay on the supply board is energized by the control panel. This occurs when the
rotor is at standstill and mains power is applied. A solenoid is energized and releases
the latch.
• The centrifuge can only be started when the lid is closed. A microswitch on the lid
lock detects the position of the lid lock.
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