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 - Edwards nEXT200200 Instruction Manual

Fault

The pump does not rotate after a serial start 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
given in The pump does not rotate after a parallel start command is sent on page
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 Reduce the pumping load or check for a gross leak into the system.
Cause The pump is too hot when in operation.
• Increase the cooling to the pump. Change from air cooling to water cooling (refer
Remedy
to Technical data on page 17
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 may be damaged. Contact supplier or us.
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
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.
B85200880_D - Fault finding
No serial comms on page 78
for maximum inlet pressure and cooling
Page 77
or do the checks
3
Pa).
76.