BUSCH COBRA NX 0950 A User manual

Ateliers Busch S.A.
Zone industrielle, 2906 Chevenez
Switzerland VACUUM APP
Get technical data, instruction manuals, service kits
2020.03.170870222540/-_en / Original instructions / Modications reserved
Dry Screw Vacuum Pumps
NX 0950 A - Water-Cooled Version
COBRA
Instruction Manual

Table of Contents
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Table of Contents
1 Safety........................................................................................................................... 4
2 Product Description ..................................................................................................... 5
2.1 Operating Principle............................................................................................... 6
2.2 Application ........................................................................................................... 6
2.3 Start Controls .......................................................................................................6
2.4 Standard Features................................................................................................. 7
2.4.1 Water Cooling ...........................................................................................7
2.4.2 Temperature Switch...................................................................................7
2.4.3 Sealing Systems .........................................................................................7
2.5 Optional Accessories............................................................................................. 7
2.5.1 Gas Ballast Valve........................................................................................7
2.5.2 Silencer......................................................................................................7
2.5.3 Barrier Gas System.....................................................................................7
2.5.4 Inlet Filter ..................................................................................................8
2.5.5 Inlet Check Valve.......................................................................................8
3 Transport ..................................................................................................................... 9
4 Storage......................................................................................................................... 10
5 Installation................................................................................................................... 11
5.1 Installation Conditions .......................................................................................... 11
5.2 Connecting Lines / Pipes ......................................................................................11
5.2.1 Suction Connection....................................................................................12
5.2.2 Discharge Connection................................................................................12
5.2.3 Cooling Water Connection ........................................................................13
5.2.4 Barrier Gas System Connection (Optional) .................................................14
5.3 Filling Oil..............................................................................................................14
5.4 Electrical Connection ............................................................................................17
5.4.1 Electrical Connection of the Variable-Frequency Drive ...............................18
5.4.2 Wiring Diagram Variable-Frequency Drive.................................................19
5.4.3 Start / Stop Connection .............................................................................19
5.4.4 Wiring Diagram Three-Phase Motor (Pump Drive).....................................20
5.5 Electrical Connection of the Monitoring Devices ................................................... 21
5.5.1 Wiring Diagram Temperature Switch .........................................................21
6 Commissioning............................................................................................................ 21
7 Maintenance................................................................................................................ 23
7.1 Maintenance Schedule.......................................................................................... 24
7.2 Oil Level Inspection .............................................................................................. 24
7.3 Cleaning the Inlet Screen ......................................................................................25
7.4 Cleaning the Gas Ballast Filter (Optional).............................................................. 25
7.5 Oil Change...........................................................................................................26
8 Overhaul...................................................................................................................... 29
9 Decommissioning ........................................................................................................ 29
9.1 Dismantling and Disposal...................................................................................... 29
10 Spare Parts................................................................................................................... 30
11 Troubleshooting........................................................................................................... 30
12 Technical Data ............................................................................................................. 32
13 Oil ............................................................................................................................... 32

Table of Contents
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14 EU Declaration of Conformity ...................................................................................... 33

1 | Safety
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1 Safety
Prior to handling the machine, this instruction manual should be read and understood. If
anything needs to be clarified, please contact your Busch representative.
Read this manual carefully before use and keep for future reference.
This instruction manual remains valid as long as the customer does not change anything
on the product.
The machine is intended for industrial use. It must be handled only by technically trained
personnel.
Always wear appropriate personal protective equipment in accordance with the local
regulations.
The machine has been designed and manufactured according to state-of-the-art meth-
ods. Nevertheless, residual risks may remain. This instruction manual highlights potential
hazards where appropriate. Safety notes and warning messages are tagged with one of
the keywords DANGER, WARNING, CAUTION, NOTICE and NOTE as follows:
DANGER
... indicates an imminent dangerous situation that will result in death or serious injuries if
not prevented.
WARNING
... indicates a potentially dangerous situation that could result in death or serious injuries.
CAUTION
... indicates a potentially dangerous situation that could result in minor injuries.
NOTICE
... indicates a potentially dangerous situation that could result in damage to property.
NOTE
... indicates helpful tips and recommendations, as well as information for efficient and
trouble-free operation.

Product Description | 2
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2 Product Description
EB IN, IS
OUT
PMR MP
BGR VFDCWD
SI
OSG
GB
OFPTSCWO
BGCBGMODP
BGFOFP
CWDODPOSG
CWI
NP MP
OUTCD
BGC Barrier gas connection BGF Barrier gas flow meter
BGM Barrier gas manometer BGR Barrier gas pressure regulator
CD Condensate drain CWD Cooling water drain plug
CWI Cooling water inlet CWO Cooling water outlet
EB Eye bolt GB Gas ballast valve
IN Suction connection IS Inlet screen
MP Magnetic plug NP Nameplate
ODP Oil drain plug OFP Oil fill plug
OSG Oil sight glass OUT Discharge connection
PMR Plug for manual rotation of rotors SI Silencer
TS Temperature switch VFD Variable Frequency Drive
NOTE
Technical term.
In this instruction manual, we consider that the term ‘machine’ refers to the ‘vacuum
pump’.

2 | Product Description
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NOTE
Illustrations
In this instruction manual the illustrations may differ from the machine appearance.
2.1 Operating Principle
The machine works on the one-stage, twin-screw pump principle.
Two screw rotors are rotating inside the cylinder. The pumped medium is trapped
between the cylinder and screw chambers, compressed, and transported to the gas out-
let. During the compression process, the two screw rotors do not come into contact with
each other nor with the cylinder. There is no need for a lubrication or an operating fluid
in the compression chamber.
2.2 Application
The machine is intended for the suction of air and other dry, non-aggressive, non-toxic
and non-explosive gases.
Conveying of other media leads to an increased thermal and/or mechanical load on the
machine and is permissible only after a consultation with Busch.
The machine is intended for the placement in a non-potentially explosive environment.
The machine is capable of maintaining ultimate pressure, see Technical Data [►32].
The machine is suitable for continuous operation.
Permitted environmental conditions, see Technical Data [►32].
NOTICE
Chemical compatibility of the process gases with the machine component materials.
Risk of corrosion inside the compression chamber which can reduce performance and
its lifetime!
• Check if the process gases are compatible with those following materials:
- Cast iron
- Steel
- Fluoroelastomer (FKM/FPM)
• In doubt, please contact your Busch representative.
2.3 Start Controls
The machine is equipped with a variable-frequency drive.

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2.4 Standard Features
2.4.1 Water Cooling
The machine is cooled by a cooling water circuit in the cylinder cover and cylinder.
2.4.2 Temperature Switch
The temperature switch monitors the cooling water temperature of the machine.
The temperature switch has one switch point:
Switch point T = 70°C Trip, the machine must be stopped, pin 1+2
2.4.3 Sealing Systems
The machine is equipped with labyrinth seals on the motor side and suction side.
Sealing systems prevent the process gas going to the bearings chambers.
Depending on the application, the sealing systems efficiency can be improved with a
barrier gas system, see Barrier Gas System [►7].
2.5 Optional Accessories
2.5.1 Gas Ballast Valve
The gas ballast valve mixes the process gas with a limited quantity of ambient air to
counteract the condensation of vapour inside the machine.
The gas ballast valve has an influence on the ultimate pressure of the machine, see Tech-
nical Data [►32].
2.5.2 Silencer
A silencer at the discharge connection (OUT) can be provided to reduce the exhaust gas
noise.
2.5.3 Barrier Gas System
The barrier gas system allows the supply of compressed air or nitrogen into the motor
side shaft seals in order to improve the sealing efficiency.

2 | Product Description
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2.5.4 Inlet Filter
The inlet filter protects the machine against dust and other solids in the process gas. The
inlet filter is available with a cartridge.
Connection size: G3'
2.5.5 Inlet Check Valve
In order to avoid reverse rotation after switching off, the machine can be equipped with
an inlet check valve.
The inlet check valve also prevents fast venting of the connected vacuum system.
The inlet check valve can also be equipped with a pressure sensor (please contact your
local Busch representative for further information).
Connection size: G1/2
Connection size: G3'

Transport | 3
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3 Transport
WARNING
Suspended load.
Risk of severe injury!
• Do not walk, stand or work under suspended loads.
WARNING
Lifting the machine using the motor eye bolt.
Risk of severe injury!
• Do not lift the machine using the eye bolt fitted to the motor. Only lift the machine as
shown.
NOTICE
In case the machine is already filled with oil.
Tilting a machine that is already filled with oil can cause large quantities of oil to in-
gress into the cylinder.
• Drain the oil prior to every transport or always horizontally transport the machine.
• Make sure that the eyebolt(s) (EB) is/are in faultless condition, fully screwed in and
tightened by hand.
Machine weight:
see the technical data or the nameplate (NP)
• Make sure that each of the slings used to lift the machine has a minimum length of
400 mm.
• Make sure that the length of each sling is exactly the same.

4 | Storage
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Minimum length :
400 mm
Minimum length :
400 mm
• Check the machine for transport damage.
If the machine is secured to a base plate:
• Remove the machine from the base plate.
4 Storage
• Seal all apertures with adhesive tape or reuse provided caps.
NOTICE
Long storage time.
Risk of damage to the machine!
• Due to a long storage time the capacitors of the variable-frequency drive can lose effi-
ciency because of electrochemical processes. In the worst case, it can lead to a short-
circuit and therefore to a damage to the variable-frequency drive of the machine.
• Connect the machine every 18 months for 60 minutes to the mains.
If the machine is to be stored for more than 3 months:
• Wrap the machine in a corrosion inhibiting film.
• Store the machine indoors, dry, dust free and if possible in original packaging
preferably at temperatures between 5 ... 55 °C.

Installation | 5
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5 Installation
5.1 Installation Conditions
NOTICE
Use of the machine outside of the permitted installation conditions.
Risk of premature failure!
Loss of efficiency!
• Take care that the installation conditions are fully complied with.
• Make sure that the environment of the machine is not potentially explosive.
• Make sure that the ambient conditions comply with the Technical Data [►32].
• Make sure that the environmental conditions comply with the protection class of the
motor and the electrical instruments.
• Make sure that the installation space or location is vented such that sufficient cooling
of the machine is provided.
• Make sure that cooling air inlets and outlets of the motor and VFD fans are not
covered or obstructed and that the cooling air flow is not affected adversely in any
other way.
• Make sure that the oil sight glass (OSG) remains easily visible.
• Make sure that enough space remains for maintenance work.
• Make sure that the machine is placed or mounted horizontally, a maximum of 1° in
any direction is acceptable.
• Check the oil level, see Oil Level Inspection [►24].
• Make sure that the cooling water complies with the requirements, see Cooling Water
Connection [►13].
If the machine is installed at an altitude greater than 1000 meters above sea level:
• Contact your Busch representative, the motor should be derated or the ambient
temperature limited.
5.2 Connecting Lines / Pipes
• Remove all protective covers before installation.
• Make sure that the connection lines cause no stress on the machine‘s connection; if
necessary use flexible joints.
• Make sure that the line size of the connection lines over the entire length is at least as
large as the connections of the machine.
In case of very long connection lines it is advisable to use larger line sizes in order to
avoid a loss of efficiency. Seek advice from your Busch representative.

5 | Installation
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5.2.1 Suction Connection
WARNING
Unprotected suction connection.
Risk of severe injury!
• Do not put hand or fingers in the suction connection.
NOTICE
Ingress of foreign objects or liquids.
Risk of damage to the machine!
If the inlet gas contains dust or other foreign solid particles:
• Install a suitable filter (5micron or less) upstream from the machine.
Connection size(s):
– G3
– DN100 ISO-K, DIN 28404
If the machine is used as part of a vacuum system:
• Busch recommends the installation of an isolation valve in order to prevent the
machine from turning backwards.
5.2.2 Discharge Connection
Discharge variants (without silencer)
Connection size(s):
At the machine discharge connection:
– G3, horizontal (orientable 180°)
– DN100 ISO-K, DIN 28404, vertical (without discharge elbow)
At the silencer (SI) discharge connection (Optional):
– DN100 ISO-K, DIN 28404, horizontal
• Make sure that the discharged gas will flow without obstruction. Do not shut off or
throttle the discharge line or use it as a pressurised air source.

Installation | 5
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• Make sure that the counter pressure (also termed back pressure) at the discharge con-
nection (OUT) does not exceed the maximum allowable discharge pressure, see Tech-
nical Data [►32].
5.2.3 Cooling Water Connection
CWI CWO
CWI Cooling water inlet CWO Cooling water outlet
• Connect the cooling water connections (CWI / CWO) to the water supply.
Connection size:
– G1/2, ISO 228-1 (CWI / CWO)
• Make sure that the cooling water complies with the following requirements:
Supply capacity l/min 8...16
Water pressure bar 1 ... 6
Supply temperature °C +10 ... +30
Required pressure differential across supply
and return
bar ≥ 1
• To reduce the maintenance effort and ensure a long product lifetime we recommend
the following cooling water quality:
Hardness mg/l (ppm) < 90
Properties Clean & clear
PH value 7 ... 8
Particle size µm < 200
Chloride mg/l < 100
Electrical conductivity µS/cm ≤ 100
Free chloride mg/l < 0.3
Materials in contact with the cooling water Stainless steel and cast iron
NOTE
Water hardness unit conversion.
1 mg/l (ppm) = 0.056 °dh (german degree) = 0.07 °e (english degree) = 0.1 °fH (french
degree)

5 | Installation
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5.2.4 Barrier Gas System Connection (Optional)
PRV FMEBGCMAN
BGC Barrier gas connection FME Flow meter
MAN Manometer PRV Pressure regulating valve
• Connect the barrier gas connection (BGC) to the gas supply.
Connection size:
– G1/4, ISO 228-1
• Make sure that the gas complies with the following requirements:
Gas type Dry nitrogen or air
Gas temperature °C 0 ... 60
Maximum gas pressure bar 13
Recommended pressure setting at the
pressure regulating valve (PRV)
bar 3
Filtration µm 5
Recommended flow rate SLM* 15 ... 20
Air quality (only for air) Acc. to ISO
8573-1
Class 5.4.4.
* standard litre per minute
5.3 Filling Oil
NOTICE
Use of an inappropriate oil.
Risk of premature failure!
Loss of efficiency!
• Only use an oil type which has previously been approved and recommended by
Busch.

Installation | 5
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For oil type and oil capacity see Technical Data [►32] and Oil [►32].
1
2
Busch Oil
MAX
MIN
3
4
Oil filling at the motor side
Check oil level
1
Busch Oil
2
MAX
MIN
3
4
Oil filling at the inlet side
Check oil level
When the oil filling is achieved:
• Write down the oil change date on the sticker.

5 | Installation
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Last oil change
__ / __ / ____
Oil type see nameplate
Change interval see
instruction manual
If there is no sticker (part no. 0565 568 959) on the machine:
• Order it from your Busch representative.

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5.4 Electrical Connection
DANGER
Live wires.
Risk of electrical shock.
• Electrical installation work must only be executed by qualified personnel.
• Make sure that the power supply for the motor is compatible with the data on the
nameplate of the motor.
• The electrical installation must comply with applicable national and international
standards.
• Provide a lockable disconnect switch on the power line so that the machine is com-
pletely secured during maintenance tasks.
• Provide an overload protection according to EN 60204-1 for the motor.
• Make sure that the motor of the machine will not be affected by electric or electro-
magnetic disturbance from the mains; if necessary seek advice from Busch.
• Connect the protective earth conductor.
• Electrically connect the motor.
• Electrically connect the Variable-Frequency Drive (VFD), see Electrical Connection of
the Variable-Frequency Drive.
DANGER
Carry out any work on the variable-frequency drive and motor.
Risk of electrical shock!
• Electrical installation work must only be executed by qualified personnel.
DANGER
Maintenance work without disconnecting the variable-frequency drive.
Risk of electrical shock.
• Disconnect and isolate the variable-frequency drive before attempting any work on it.
High voltages are present at the terminals and within the variable-frequency drive for
up to 10 minutes after disconnection of the electrical supply.
• Always ensure by using a suitable multimeter that no voltage is present on any drive
power terminals prior to commencing any work.
NOTICE
The admissible motor nominal speed exceeds the recommendation.
Risk of damage to the machine!
• Check the admissible motor nominal speed (nmax) on the nameplate of the machine
(NP).
• Make sure to comply with it.
• Consult the Technical Data [►32] to get more information.

5 | Installation
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NOTICE
The motor frequency is below 20 Hz.
Risk of damage to the machine!
• The motor nominal speed must always be higher than 1200 min-1 (20 Hz).
NOTICE
Incorrect connection.
Risk of damage to the motor!
• The wiring diagrams given below are typical. Check the inside of the terminal box for
motor connection instructions/diagrams.
5.4.1 Electrical Connection of the Variable-Frequency Drive
The following applies to machines equipped with an on-board variable-frequency drive
(VFD).
• Make sure that the power supply for the drive is compatible with the data on the
nameplate of the variable-frequency drive.
• Make sure that the motor of the machine will not be affected by electric or electro-
magnetic disturbance from the mains; if necessary seek advice from Busch.
• Remove the cover from the Variable-Frequency Drive (VFD). The cover is connected
to the PE terminals with a PE cable. Do not interrupt this cable.
PE cable
• Connect the mains cable as shown in the chapter Wiring Diagram Variable-Frequency
Drive [►19].

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5.4.2 Wiring Diagram Variable-Frequency Drive
CAUTION
The machine can start immediately when power is supplied.
Risk of inadvertent start-up!
• Make sure that a start-up will not lead to a dangerous situation.
1
2
PE
L1
L2
L3
PEL1 L2 L3
VFD
L1
L2
L3
PE
M
Connect PE
Motor already wired
Connect L1, L2, L3
5.4.3 Start / Stop Connection
The following applies to machines equipped with an on-board variable-frequency drive
(VFD).
• The Variable-Frequency Drive (VFD) is delivered with preset factory parameters.
Please refer to the specific wiring diagram supplied inside the Variable-Frequency
Drive (VFD).
• For the connection of the control cables, install a cable in a bore hole at the terminal
box (TB). Use EMC cable fittings if required.
• These parameters can be changed according to the specific document “Pump Control
Instructions, art. no.: 0870208958”. Contact your local Busch agency or your Busch
representative to check if your machine is a custom or a standard one.

5 | Installation
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5.4.4 Wiring Diagram Three-Phase Motor (Pump Drive)
The following applies to machines not equipped with an on-board variable-frequency
drive (VFD) and on which an external frequency drive can be installed.
• Make sure that you select the proper frequency drive according to the motor specific-
ations.
• Connect the motor to your external frequency drive according to the operating in-
structions of your external frequency drive.
• Connect the motor cables as shown in the below wiring diagram.
Delta connection (low voltage): Star connection (high voltage):
NOTICE
Incorrect direction of rotation.
Risk of damage to the machine!
• Operation in the wrong direction of rotation can destroy the machine in a short time!
Prior to start-up, ensure that the machine is operated in the right direction.
The intended rotation direction of the motor is defined by the illustration below:
IN
• Jog the motor briefly.
• Watch the fan wheel of the motor and determine the direction of rotation just before
the fan wheel stops.
If the rotation of the motor must be changed:
• Switch any two of the motor phase wires.