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Operation
D395-93-880 Issue A
4.4 Gas-ballast control (E2M1.5)
Use the gas-ballast control (Figure 1, item 1) to change the amount of air (or inert gas) introduced into the low
vacuum stage of the pump. Use of the gas-ballast will prevent the condensation of vapours in the pump; the
condensates would contaminate the oil.
Use the gas-ballast control closed:
to achieve ultimate vacuum
to pump dry gases.
Turn the gas-ballast control six turns anti-clockwise to open it fully. Use the gas-ballast control open:
to pump high concentrations of condensable vapour
to decontaminate the oil.
When you operate the pump with the gas-ballast control open, there will be an increased rate of oil loss from the
pump.
4.5 Electrical supply failure
If the electrical supply to the T-Station fails when the Turbo pump is rotating, the motor of the pump is used as a
generator. The regenerated power is used to maintain the control system and the display.
As the pump rotational speed decreases, the motor's ability to generate power also decreases until it is no longer
able to maintain power to the control system. This will occur at speeds below 50% full rotational speed. Therefore
you will not have any indication about pump rotational speed, yet the impeller may still be turning.
When the power is reinstated after a power failure, the behaviour of the T-Station will depend on the length of time
the pump was without power: if the power is reinstated before regenerative power has ceased the system will re-
start; if the power is reinstated after regenerative power has ceased the system will not re-start.
If the power supply fails when the pump is running, the impeller could continue to spin for
approximately 10 minutes. The control circuit may not give any indication that the impeller is still
running.
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