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3.3 Motor
M1
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The motor is a three- phase asynchronous motor with two pairs of poles.
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The motor is protected against overheating by an overtemperature switch.
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The power board evaluates the overtemperature switch.
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The motor is controlled by the power board with a three-phase current with variable
frequency and voltage.
3.4
Speed sensor B3
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The speed sensor (speedometer) is located at the bottom of the motor.
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The speed signal (2 pulses per revolution) will be triggered by two magnets fixed at
the motor axle.
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The speed of the rotor is monitored and controlled by the power board.
3.5
Brake resistor R1 and Overtemperature fuse F3
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The braking copper which is integrated on the power board transfers the electrical
energy produced during braking, from a voltage of 380 V with the 230 V version and
203 V with the 120 V version, to the brake resistor in a controlled manner.
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An overtemperature fuse protects the brake resistor against overheating. When the
overtemperature fuse (F3) blows, the power board will be separated from the power
supply.
3.6
Lid lock Y1
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Opening of the lid lock is prevented by a latch. The lid lock can only be opened when
the relay REL 602 on the power board is energised. This occurs when the rotor is at
standstill, mains power is applied and the key is pressed. The solenoid is ener-
gized for three seconds and releases the latch.
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The centrifuge can only be started when the lid is closed. A microswitch on the lid
lock detects the position of the lid lock (open/closed) and report it to the power
board.
3.7
Imbalance switch S 2
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A switch detects any imbalance.
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Imbalance can only be detected in running mode (starting, centrifuging and braking).
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If any imbalance is detected, the drive is changed over to braking.
