Overspeed System; Rotor Energy System; Drive - Beckman Coulter Optima L Series Instruction Manual

OVERSPEED SYSTEM

ROTOR ENERGY SYSTEM

DRIVE

2 U.S. Pat. No. 4,846,773.
The overspeed system is a safety feature designed to ensure that the
rotor does not exceed its maximum allowable speed. This system
includes photoelectric sensors in the rotor chamber next to the drive
spindle (see Figure 1-2) and an overspeed disk on the bottom of the
rotor. Individual rotor manuals provide information on the correct
overspeed disks to be used with each rotor.
The overspeed disk has alternating light and dark sectors. As the rotor
spins, the passage of reflecting and nonreflecting sectors over the
photoelectric device generates a series of pulses that are detected
by electronic circuitry. If the pulse rate, which is dependent on the
number of sectors on the disk and the speed of the rotor, exceeds a
set limit, the SPEED diagnostic message will light and the rotor will
automatically coast to a stop.
When the rotor reaches 1000 rpm, the set speed is checked against the
overspeed disk. If the overspeed disk indicates a maximum allowable
speed that is lower than the set speed, the set speed is automatically
lowered to the maximum speed permitted by the disk and a SPEED
diagnostic message is displayed to alert you to the change. (In the
mode, the time setting is recalculated to give an equivalent
value.)
As the rotor accelerates between 15 000 and 21 000 rpm, rotor inertia
is measured and the rotor energy is calculated for the speed set by the
user. If the calculated rotor energy is determined to be excessive, a
SPEED diagnostic message will appear and the instrument will
immediately shut down.
The Optima L series ultracentrifuges use a frequency-controlled, air-
cooled direct-drive induction motor that requires no gears or brushes.
In addition, the drive does not require an oil vacuum seal, external oil
reservoir, or continuously operating damper.
forced air and internally cooled by oil, the drive delivers ultrasmooth,
quiet performance, with high tolerance of rotor imbalance.
Description
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2
ω
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2
2 Externally cooled by
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1-7