B800-00-880 Issue D
Page 4
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Edwards and the Edwards logo are trademarks of Edwards Limited.
Introduction
1.4.2
Standby speed
In standby mode, the pump rotational speed is lower than the full rotational speed. The default setting for standby
speed is 70% of full speed. Note that in order to run at standby speed, the pump must also be in the start condition.
If the application does not require the pump to be running at maximum speed at all times, use the standby speed
feature rather than switching the pump off. This feature can be used for vacuum system tuning or as a system power
saving option.
The standby speed is a user-selectable value (refer to
Section 4.1.4
).
1.4.3
Timer
When the pump is started, an internal timer is automatically started within the drive electronics. The default timer
setting is 8 minutes. If the pump fails to reach 50% of full rotational speed within the timeout period, the controller
will signal a Fail and will decelerate the pump to rest. This feature prevents the controller from driving the pump at
maximum power for a long time. The pump may fail to reach 50% speed if the gas load is too high (for example if
there is a leak in the system), if the backing pump fails or if the pump is too hot.
The timeout period is a user-selectable feature (refer to
Section 4.1.6
). If the application requires the pump to ramp
up slowly, extend the timeout period. The timer is permanently enabled for ramp-up.
The timer has an additional function: if the pump rotational speed drops below 50% of full speed for any reason, the
pump time can be set to recover rather than trigger a fail condition. The timer starts as soon as the speed drops to
below 50% full speed. If, during the timeout period, the pump recovers to above 50% full speed then the timer will
be reset. If the pump rotational speed fails to recover by the end of the timeout period, the controller will trigger a
fail condition and will decelerate the pump to rest. When the pump is shipped, the timer function is enabled,
however, it can be disabled. With the timer disabled, the pump will fail and decelerate to rest as soon as pump
rotational speed falls below 50%.
1.4.4
Analogue output
The pump controller produces an analogue output for monitoring four different system parameters:
Measured pump rotational speed (default condition)
Measured motor power
Measured motor temperature
Measured controller temperature
The analogue output signal ranges from 0 to 10 V and is directly proportional to the system parameter (refer to
Section 2.8
).
Connect the analogue output to a suitable meter or indicator to display the appropriate system parameter or connect
it to the customer control equipment (for example, to operate other components in the pumping system at preset
values).
Only one system parameter can be monitored at a time using the analogue output. However, it is easy to configure
the controller to monitor a different system parameter (refer to
Section 4.1.7
).
1.4.5
Automatic vent options
An Edwards TAV vent valve can be connected directly to the nEXT pump’s controller. The controller is capable of
providing a number of different venting options.
The drive electronics can control the rate of venting. Using this feature the pump can be vented from full rotational
speed in a controlled manner that will not damage the pump bearings. Once the pump rotational speed has dropped
to below 50% of maximum speed, it is safe to hard vent (open the vent valve fully).
