Edwards nEXT200200 - The Pump Does Not Rotate after a Serial Start Command Is Sent; The Pump Does Not Respond in Multi- Drop Mode; The Green Normal LED Does Not Light or the Pump Does Not Rotate at Full Speed or the Pump Fails While in Operation; Ultimate Pressure Cannot be Reached

Fault The pump does not rotate aer a serial s
tart command is sent
Cause Check if the pump returns a reply to the start command.
Remedy If there is no reply, do the checks given in No serial c
omms on page 78 or do the checks
given in The pump does not rotate aer a parallel start command is sent on page 76.
Fault The pump does not respond in mul- dr
op mode
Cause The mul-dr
op is disabled.
Remedy Make sure the pump has a mul-drop address. Make sure that the commands are sent
using the mul‑drop protocol.
Fault The green Normal LED does not light or the pump does not rotate at full speed or the
pump f
ails while in operaon
Cause The inlet pressure is too high.
Remedy Reduce the pumping load or check for a gross leak into the system.
Cause The pump is too hot when in oper
aon.
Remedy
• Increase the cooling to the pump. Change from air cooling to water cooling (refer
to Technical data on page 17 for maximum inlet pressure and cooling
requirements).
• Increase cooling water ow 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 may be damaged. Contact supplier or us.
Fault Ulmate pr
essure 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 sucien
t (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 incr
eased. 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
P
a).
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.
Page 77
B85200880_D - Fault nding