The vacuum pump or the drive motor is
blocked
Make sure the drive motor is disconnected
from the power supply
Remove the fan cover
Try to turn the drive motor with the vacuum
pump by hand
If the unit is still frozen: remove the drive mo-
tor and check the drive motor and the vacuum
pump separately
If the vacuum pump is blocked:
Repair the vacuum pump (Busch service)
The drive motor is defective
Replace the drive motor (Busch service)
(the proper function of the fan wheel requires
the precise adjustment of the coupling on the
motor shaft and on the pump shaft; therefore
the motor can be mounted by the Busch ser-
vice only)
The vacuum pump is blocked
Solid foreign matter has entered the vacuum
pump
Repair the vacuum pump (Busch service)
Make sure the suction line is equipped with a
screen
If necessary additionally provide a filter
Corrosion in the vacuum pump from remain-
ing condensate
Repair the vacuum pump (Busch service)
Check the process
Observe the chapter Conveying Condensable
Vapours (
Ú
page 8)
Version with three-phase motor:
The vacuum pump was run in the wrong di-
rection
Repair the vacuum pump (Busch service)
When connecting the vacuum pump make
sure the vacuum pump will run in the correct
direction (
Ú
page 6: Installation)
The drive motor is running, but the vacuum
pump stands still
The coupling between the drive motor and
the vacuum pump is defective
Replace the coupling element
The vacuum pump starts, but labours or runs
noisily or rattles
The drive motor draws a too high current
(compare with initial value after commission-
ing)
Loose connection(s) in the drive motor termi-
nal box
Version with three-phase-motor:
Not all drive motor coils are properly con-
nected
The drive motor operates on two phases only
Check the proper connection of the wires
against the connection diagram
(particularly on motors with six coils)
Tighten or replace loose connections
Version with three-phase motor:
The vacuum pump runs in the wrong direction
Verification and rectification
Ú
page 5: Instal-
lation and Commissioning
Foreign objects in the vacuum pump
Stuck bearings
Repair the vacuum pump (Busch service)
The vacuum pump runs very noisily
Defective bearings
Repair the vacuum pump (Busch service)
Worn coupling element
Replace the coupling element
Low oil level in the synchronising gear
The synchronising gear is leaky
Repair the vacuum pump (Busch service)
Synchronising gear damaged due to operation
with low oil level
Repair the vacuum pump (Busch service)
The vacuum pump runs very hot
Insufficient air ventilation
Make sure that the cooling of the vacuum
pump is not impeded by dust/dirt
Clean the fan cowlings, the fan wheels, the
ventilation grilles and the cooling fins
Install the vacuum pump in a narrow space
only if sufficient ventilation is ensured
Ambient temperature too high
Observe the permitted ambient temperatures
Temperature of the inlet gas too high
Observe the permitted temperatures for the
inlet gas
MM 1324, 1202, 1252, 1322, 1200, 1250, 1320 AV
Troubleshooting
0870133276 / 070328
page 11
