D396-14-880 Issue J
Page 36 © Edwards Limited 2008. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Operation
4.8 Automatic shutdown after Fail condition
The EXC120, EXC120E and EXC300 Controllers will automatically switch off the electrical supply to the EXT pump if
the Controller trips into Fail condition (see Section 1.9), though the EXC300M Controller will continue to provide an
electrical supply for the electromagnetic bearings of the EXT250M pump.
If the SYS Interlock opens (see Section 1.7.3), the Controller will automatically open the vent-valve and (on the
EXC120, EXC300 and EXC300M Controllers) will automatically open the backing pump relay. The operation of the
vent-valve and backing pump in all other Fail conditions depends on how you have configured the Controller: refer
to Section 3.13.
4.9 Reset the Controller after Fail condition
Note: You can only reset the EXC300M Controller after an Axial Emergency condition if the EXT pump speed is
below 10% of full rotational speed.
To reset a Fail condition, press the Start/Stop button (Figures 1 and 2, item 4) to select Stop, then press it again, or
(if you have connected your equipment to the logic interface) open the Start/Stop input on the logic interface for a
minimum time of 300 ms and then close the input.
4.10 Electrical supply failure
If the electrical supply to the Controller fails when the EXT pump is rotating:
z The backing pump shuts down (due to the electrical supply failure).
z The motor of the EXT pump is used as a generator and the electrical supply for the vent-valve is maintained
until the pump speed falls to 50% of full rotational speed, then the electrical supply for the vent-valve is
switched off.
z EXC120, EXC120E and EXC300 Controllers will then shut down. On the EXC300M Controller, the motor of the
EXT pump will continue to act as a generator until pump speed is reduced to approximately 10% of full
rotational speed. The EXC300M Controller then shuts down and the EXT250M pump rotor drops onto its safety
bearings.
If Start is selected, the Controller will automatically restart the EXT pump when the electrical
supply is restored after an electrical supply failure. Ensure that people cannot be injured by the
rotating rotor blades of the EXT pump.
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