D396-14-880 Issue J
Page 10 © Edwards Limited 2008. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Introduction
1.8 Vent-valve control
Notes: 1. The EXC120E Controller does not have a backing pump relay.
2. The vent option factory settings are shown in Table 7.
Provided that the SYS Interlock is closed: if the Controller electrical supply fails, the Controller maintains the
electrical supply to the vent-valve until the pump speed falls to below 50% of full rotational speed. The Controller
then switches off the vent-valve electrical supply and opens the backing pump relay. This feature of the Controller
cannot be reconfigured.
However, you can use the configuration DIP switches on the Controller (refer to Section 3.13) to select any one of
(or any combination of) the following options:
z Vent on Stop (Stop selected either by the front-panel button or the Start/Stop input on the logic interface).
z Vent on Fail condition.
z Vent on Axial Emergency condition (only available on the EXC300M Controller: see Section 1.9.3).
When a selected vent option condition is detected, the Controller:
z waits approximately 2 seconds, to allow a vacuum system isolation-valve (if fitted) to close,
z then switches off the electrical supply to the vent-valve,
z then opens the backing pump relay.
1.8.1 Vent on Stop
Note: If the SYS Interlock opens, a Fail condition will occur and the Controller will switch off the vent-valve
electrical supply: see Sections 1.9.1 and 3.13.
Vent on Stop selected
When you switch on the Controller, the vent-valve electrical supply remains off until Start is selected. Provided that
the SYS Interlock is closed, the Controller switches the vent-valve electrical supply on when Start is selected.
If Stop is then selected, the Controller switches the vent-valve electrical supply off again.
Vent on Stop not selected
When you switch on the Controller, the vent-valve electrical supply remains off until Start is selected. Provided that
the SYS Interlock is closed, the Controller switches the vent-valve electrical supply on when Start is selected.
If Stop is then selected, the EXT pump will decelerate. The vent-valve electrical supply will remain on until the pump
speed falls to below 50% of full rotational speed, at which point the vent-valve electrical supply will be switched off.
1.8.2 Vent on Fail and Vent on Axial Emergency
Note: The Vent on Axial Emergency option is only available on the EXC300M Controller.
If the Controller is configured to Vent on Fail or Vent on Axial Emergency, the Controller will switch off the vent-
valve electrical supply as soon as Fail condition or Axial Emergency condition is detected.
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