B722-40-880 Issue F
Page 2 © Edwards Limited 2013. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Introduction
Do not attempt to separate the Podule from the pump since this will cause damage to the electrical connections.
The DX pumps consist of the compound turbomolecular pump with a permanently attached Podule containing drive
electronics.
The Podule controls the electrical supply to the pump. It has no manual controls and can only be operated through
the logic interface. To operate the DX pump, connect it to the customer control equipment and power supply or use
the Edwards TIC Turbo Instrument Controller or TIC Turbo Controller.
The Podule drives the brush-less d.c. motor in the pump. The pump has three Hall effect devices that operate as
rotor position sensors and ensure that the drive current is correctly commutated around the motor phase windings.
The vacuum pump contains turbomolecular blades and a Holweck drag mechanism on a single shaft; the Holweck
mechanism allows operation at higher backing pressures than pure turbomolecular pumps.
DX pumps are supplied with an inlet screen fitted into the bore of the inlet flange. Both the EXT255iDX and the
EXT75iDX with an NW25 interstage port are supplied with an inlet strainer that fits into the interstage port. The inlet
screen and inlet strainer protect the pump against damage that would be caused by debris entering the pump. The
inlet screen also protects the user against injury from the sharp blades in the pump.
Note: The EXT75iDX with an NW16 interstage port is not supplied with an inlet strainer.
The DX pumps have a vent port for venting the pump and vacuum system to atmospheric pressure. The pump is
supplied with a manual vent valve fitted. This can be replaced with a TAV5 or TAV6 solenoid-operated vent valve
(available as accessories – see Section 7).
The DX pumps have a purge port. An inert purge gas can be introduced through the port to protect the bearing and
motor from corrosion, or the bearing lubricant from oxidisation. An optional vent port adapter and purge restrictor
can be fitted to the purge port to control the flow rate of the purge gas and to filter the gas supply. (Refer to
Section 7).
Air coolers and a water-cooling block are available as optional accessories to cool the DX pumps. (Refer to Section 7).
1.3 Drive electronics
The Podule contains the drive electronics that control the pump operation and accessories such as a TAV vent valve
or air cooler. There is a connector socket on the top of the Podule where the TAV vent valve or air cooler can be
plugged in. (Refer to Section 2.9)
The Podule has two indicator LEDs that signal the status and operation of the pump, that can also be used for fault
finding if a problem should occur. (Refer to Section 2.10)
The drive electronics system has a number of built-in safety features to protect the DX pumps from damage in the
event of sustained high pressure or temperature:
The electronics constantly monitor the temperature inside the Podule and the temperature of the motor
within the pump. If either part becomes too hot, the electronics reduce the power supplied to the pump
motor and the pump speed will drop. If the pump rotational speed falls below 50% full speed, the electronics
may trip into Fail condition, depending on the system configuration. (Refer to Section 1.4.3).
If the pump inlet pressure increases, the power supplied to the pump motor increases to counteract the gas
frictional load. However, when the built-in maximum power limit is reached, the speed of the pump will start
to drop. If the pump rotational speed falls below 50% full speed, the electronics may trip into Fail condition,
depending on the system configuration. (Refer to Section 1.4.3).
The Podule contains electrolytic capacitors and, under certain fault conditions, may emit
dangerous fumes. Ensure that the Podule is operated in a well-ventilated area.
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