3.3.1 Power limit setting
Select the maximum power that will be drawn by the pump. The more power supplied,
the quicker the pump will accelerate to reach full speed.
If the application requires fast cycling or higher gas loads, set the power limit to the
maximum value. If ramp time is not important in the application, use a lower power
limit, down to a minimum value (refer to Table: Power limit setting). Also ensure there is
sufficient cooling for the application.
Ensure that the power supply is capable of delivering sufficient power to the nEXT pump.
By choosing a lower power limit setting, a smaller power supply may be used. For more
information, refer to Electrical data on page 40.
3.3.2 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.
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 Standby speed setting on page 84).
3.3.3 Timer
When the pump is started, an internal timer is automatically started within the motor
controller. The default timer setting is 8 minutes.
If the pump fails to reach 50% of full rotational speed within the timeout period, the
motor controller will signal a fail and will decelerate the pump to rest. This feature
prevents the motor 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 Timer setting and options on
page 85). 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
motor 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%.
3.3.4 Analogue output
The motor controller can produce an analogue output for monitoring system
parameters.
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