Edwards nEXT 55, Instruction Manual, Page: 91 / 116

Fault The pump does not respond in multi- drop mode
Cause The multi-drop is disabled.
Remedy Make sure the pump has a multi-drop address. Make sure that the commands are
sent using the multi
‑
drop protocol.
Fault The green Normal LED does not light or the pump does not rotate at full speed or
the pump fails while in operation
Cause The inlet pressure is too high.
Remedy Decrease the pumping load or check for a gross leak in the system.
Cause The pump is too hot while in operation.
Remedy
▪ Increase the cooling of the pump. Change from air-cooling to water-cooling
(refer to Table: Pump performance data for maximum inlet pressure and
cooling requirements).
▪ Increase cooling water flow or decrease the water temperature or do both.
▪ Check that external heat sources (such as system bakeout heaters) are not
excessive.
Cause The rotor does not rotate freely.
Remedy The pump bearings can be damaged. Contact us or the supplier.
Fault Ultimate pressure cannot be reached
Cause Pressure is limited by water vapour.
Remedy Bake the system and pump.
Cause The vacuum gauges are contaminated.
Remedy Clean or replace the vacuum gauges.
Cause Pumping speed is not sufficient (because of poor conductance between the pump
and the gauge or the chamber is too large).
Remedy Increase the conductance or decrease the volume.
Cause Inlet pressure is more than 0.5 mbar (50 Pa).
Remedy If the interstage inlet pressure is too high, the inlet pressure at the turbomolecular
inlet is increased. Make sure that the interstage inlet pressure is less than 0.5 mbar
(50 Pa).
Cause
The backing pressure is more than 10 mbar (1x10
3
Pa).
Remedy The backing pressure can be too high. Check for backing pipeline leaks. If the
throughput is high, a larger backing pump can be necessary.
Cause The high vacuum area of the system is contaminated.
Remedy Clean the high vacuum system.
Cause Check the system for leaks and contamination.
Remedy If a leak is found, repair it and clean the contamination.
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B8G000880_E - Fault finding