Operating The Pump; Low Speed Operation - Varian Turbo-V 250 969-9423 Bedienungshandbuch

Operating the Pump

After the starting period, if the system has a vacuum
leak or the pressure in the pump/chamber is high (from
1 mbar to atmosphere), the pump continues to operate
indefinitely. If the gas load at the turbopump inlet flange
continues to stay high, the power drawn by the
turbopump increases up to the maximum value. Than
the Turbo-V pump is slowed down in proportion to the
gas load at least until it reaches 3 KRPM.
Even if any previous display selection was made.
This will occur either in NORMAL operation or with the
LOW SPEED selected. As soon as the gas load
decreases, the pump will automatically accelerate to
reach normal operation. The pump can be stopped at
any rotational speed and can be restarted at any
rotational speed from either the front panel buttons or
the remote connections. The controller automatically
synchronizes the output to the rotational speed of the
pump and then accelerates linearly up to the nominal
speed or within steps if the Soft Start has been
selected.

Low Speed Operation

With the FRONT panel operation selected, the remote and RS
232 operations are inoperative; conversely, the CYCLE
NUMBER and PUMP CURRENT pushbuttons are always
active, even when the operating mode selected is REMOTE or
RS 232.
This feature is provided for operating the pump at
moderate high pressure with high gas throughput. To
operate in this low speed mode, engage the LOW
SPEED pushbutton once if the display shows:
R E A D Y F O R
S O F T S T A R T
or:
P U M P R E A D Y
S T A R T
or:
N O R M A L
X X
NOTE
L O C A L
: P U S H
B U T T O N
O P E R A T I O N
K R P M
or twice if the display shows other parameters, either
before starting the pump or after it is operating.
If LOW SPEED is selected before starting the pump,
the display shows:
R E A D Y
S O F T S T A R T
The pump reaches the Normal high speed, then
decrease the speed to the low speed value and the
display shows:
A P P R O A C H
X X
If the Soft Start has been deselected the display shows:
P U M P R E A D Y
S T A R T
where: LS = means low speed mode is selected.
After starting, a LS appears on the right bottom corner
of the following displays:
S O F T S T A R T
[ - - -
P U M P I
1 2 X X
N O R M A L
X X
68
TECHNICAL INFORMATION
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B U T T O N
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S S T A R T
K R P M
O P E R A T
K R P M
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L S
L S
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