VACUUBRAND CVC 3000 - Manual (Page 36)

page 36 of 80
Vac Control function
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Vacuum control to a preset vacuum value
• Operation of a vacuum pump via in-line valve
• Operation of a vacuum pump without in-line valve with VMS (Vac-
uum Management System, see ”Accessories”)
• Operation on demand of a speed controlled pump (NT VARIO /
VARIO-B)
Preselections
+
Use the selection knob to select the parameters. All parameters can
be altered even while operation control is running.
+
Set vacuum: The ”Set vacuum” is the set point for vacuum control with
pinpoint precision for NT VARIO / VARIO-B pumps. The ”Set vacuum”
is also the lower set point for two-point vacuum control (operation with-
out a NT VARIO / VARIO-B pump).
The ”Set vacuum” is adjustable in a range of 0-795 Torr (0-1060 mbar);
when operating a NT VARIO / VARIO-B pump the control range is
1-795 Torr (1-1060 mbar) or can be set to ”Turbo”. The selection ”Tur-
bo” leads to the optimum backing pressure for a turbomolecular pump.
+
Hysteresis: The ”Hysteresis” is the control bandwidth of the two-point
control. A too small hysteresis will lead to frequent switching of the
valve or the pump. A too large hysteresis will lead to imprecise control.
Suggested ”Hysteresis” values (see table) are stored in the controller
(setup ”Auto”) and are adapted automatically to the preset pressure.
The hysteresis can be adapted at any time.
The ”Hysteresis” is adjustable in a range of 1-225 Torr (1-300 mbar) or
can be set to ”Auto”.
NT VARIO / VARIO-B pumps are controlled without hysteresis.
Set vacuum in Torr 5 10 50 80 100 200 500 700
Hysteresis in Torr
(suggested values)
2 2 5 8 9 17 40 55