Edwards nEXT nEXT85 - Operational Features; Power Limit Setting; Standby Speed; Timer

electrical supply to the controller, the vent valve or the fan aached to the controller
connector unl the pump speed decreases below 50% of the full rotaonal speed to
make sure that the vent valve stay shut unl below 50% of the full rotaonal speed and
prevent the pump from venng at full speed. It makes sure that the serial link and
signals on the parallel interface stays acve unl the pump speed decreases below 50%.
2.3 Operaonal features
The pumps have basic start and stop commands and some other features that allow the
pump operaon to be modied for an applicable applicaon.
2.3.1 Power limit seng
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 applicaon requires fast cycling or higher gas loads, set the power limit to the
maximum value. If ramp me is not important in the applicaon, use a lower power
limit, down to a minimum value (refer to Table: Power limit seng on page 60). Also
ensure there is sucient cooling for the applicaon.
Ensure that the power supply is capable of delivering sucient power to the nEXT pump.
By choosing a lower power limit seng, a smaller power supply may be used. For more
informaon, refer to Electrical data on page 22.
2.3.2 Standby speed
In standby mode, the pump rotaonal speed is lower than the full rotaonal speed. The
default seng for standby speed is 70% of the full speed.
To operate the pump at standby speed, it must be in the start condion.
If operang the pump at maximum speed at all mes is not necessary for the
applicaon, use the standby speed feature rather than seng the pump to o. You can
use the standby speed feature for tuning the vacuum system or as a power saving opon
for the system.
The standby speed is a user‑selectable value. Refer to Standby speed seng on page 61.
2.3.3 Timer
When the pump is started, an internal mer starts automacally in the motor controller.
The default mer seng is 8 minutes.
If the pump fails to reach 50% of full rotaonal speed in the meout period, the motor
controller will signal a fail and decelerate the pump to rest. This feature prevents the
motor controller from driving the pump at maximum power for a long me. The pump
can 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 meout period is user‑selectable (refer to Timer seng and opons on page 62). If
slow ramp‑up of the pump is necessary for the applicaon, extend the meout period.
The mer is permanently enabled for ramp‑up.
If the rotaonal speed of the pump decreases below 50% of the full speed, the pump
me can be set to recover rather than trigger a fail condion. The mer starts
Page 12
B8G000880_D - Introducon