Symptom
Check
Action
The EXC300M Controller
trips into ‘Fail’ during the
ramp-up and before 50%
speed is reached
(continued).
Is operating temperature of
the EXT250M too high?
Increase the cooling-water flow
or decrease the water
temperature or do both. You
may need to change from free
convection to forced air cooling
or water cooling. (Refer to
Section 2 for maximum inlet
pressure and cooling
requirements). Check that
external heat sources (such as
system bakeout heaters) are not
excessive.
Is this the first ramp-up after
a safety bearing touchdown?
Can you hear a continuous
noise from the safety bearings
during the
ramp-up?
The EXT250M pump safety
bearings are damaged. Consult
your supplier or your nearest
BOC Edwards company.
If none of the above, increase the
timer setting (refer to the
instruction manual supplied with
the EXC300M Controller). If the
EXC300M Controller still trips
into ‘Fail’, consult your supplier
or your nearest BOC Edwards
company.
The EXC300M Controller
trips into ‘Fail’ after 50%
speed has been reached -
the first two speed LEDs
are on.
Is the pressure too high?
If so, reduce the pumping load or
check for a gross leak into the
system.
If the high gas load is temporary,
configure the EXC300M
Controller to delay the ‘Fail’ trip
on 50% speed and set an
appropriate delay time (refer to
the instruction manual supplied
with the EXC300M Controller).
Is the operating temperature
of the EXT250M too high?
Increase the cooling-water flow
or decrease the water
temperature or do both. You
may need to change from free
convection to forced air cooling
or water cooling.
Does the EXT250M pump
rotor rotate freely?
If not, the EXT250M pump safety
bearings are damaged. Consult
your supplier or your nearest
BOC Edwards company.
EXT250M Turbomolecular Pump
29
Table 7 - Fault finding (continued)
