The vacuum pump starts, but labours or runs
noisily or rattles
The drive motor draws a too high current (com-
pare with initial value after commissioning)
Connections in the drive motor terminal box are
defective
Not all drive motor coils are properly connected
The drive motor operates on two phases only
Check the proper connection of the wires
against the connection diagram
Tighten or replace loose connections
The vacuum pump runs in the wrong direction
Verification and rectification see “Installation
and Commissioning”, correct if necessary
Standstill over several weeks or months
Let the vacuum pump run warm with inlet
closed
Improper oil quantity, unsuitable oil type
Use the proper quantity of one of the recom-
mended oils
(see “Oil”, oil change see “Maintenance”)
No oil change over extended period of time
Perform oil change incl. flushing (see “Mainte-
nance”)
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)
The vacuum pump runs very hot
(the oil sump temperature shall not exceed
100 °C)
Cooling water flow too low
Check the cooling water circuit and adjust the
flow if necessary
Ambient temperature too high
Observe the permitted ambient temperatures
Temperature of the inlet gas too high
Observe the permitted temperatures for the
inlet gas
Oil level too low
Top up oil
Check the oil filler plugs
Check the mechanical seals (option)
Mains frequency or voltage outside tolerance
range
Provide a more stable power supply
Partial clogging in the suction or discharge line
Remove the clogging
Long suction, discharge or pressure line with
too small diameter
Use larger diameter
Cooling water too low
Quick coupler for cooling water dislocated
Water supply pressure too low
Cooling water piping obstructed
Leakage of cooling water piping
Connect the quick couple
Apply proper pressure
Clean/ replace piping
Replace seals
Pump temperature too high
Failure of discharge line
Back pressure of pump too high
Cooling water flow too low
Vacuum contaminated with product residues
Ambient temperature too high
Check the discharge line
Che the discharge piping
Check the cooling system
Disassemble the vacuum pump
Check the limits of use
Oil level too low
Oil too low
Oil leakage
Check the oil casing sealings
Refill with oil
Cooling liquid temperature too high
Lack of cooling liquid
Escape of cooling liquid
Fill with cooling liquid
Check off the cooling liquid circuit
Troubleshooting
DP 80-2000 C-T
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0870564647 (En)
Summary of Contents for COBRA NS 0070-0160 C
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