Edwards nEXT730 - Page 112

B8J200880_E - Fault finding
Page 111
Cause The multi-drop is disabled.
Fault
The green Normal LED does not light or the pump is not rotating at full speed or
the pump fails whilst running
Cause The inlet pressure is too high.
Cause The pump is running too hot.
Cause The rotor does not rotate freely.
Fault Ultimate pressure cannot be reached
Cause Pressure is limited by water vapour.
Cause The vacuum gauges are contaminated.
Cause
Pumping speed is insufficient due to poor conductance between the pump and
the gauge or
the chamber is too large.
Cause Inlet pressure is > 0.5 mbar (50 Pa).
Cause
The backing pressure is > 10 mbar (1x10
3
Pa).
Cause The high vacuum area of the system is contaminated.
Cause Check the rest of the system for leaks and contamination.
Remedy Make sure the pump has a multi-drop address and that commands are sent using
the multi‑drop protocol.
Remedy Reduce the pumping load or check for a gross leak into the system.
Remedy
▪ Increase the cooling to the pump. Change from air cooling to water cooling
(refer to Table: Technical data nEXT730, nEXT930 and Table: Technical data
nEXT1230 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.
Remedy The pump bearings may be damaged. Contact the supplier or us.
Remedy Bake the system and pump.
Remedy Clean or replace the vacuum gauges.
Remedy Increase the conductance or reduce the volume.
Remedy If the interstage inlet pressure is too high, inlet pressure at the turbomolecular inlet
is increased; ensure that the interstage inlet pressure is < 0.5 mbar (50 Pa).
Remedy The backing pressure may be too high. Check for backing pipeline leaks. If the
throughput is high, a larger backing pump may be required.
Remedy Clean the high vacuum system.
Remedy If found, repair the leaks and clean the contamination.
Fault The pump does not respond in multi- drop mode