Compressor Drive
Motor, VSD & Coupling Selection
Compressor drives are usually medium-voltage, run continuously, and have to match the compressor torque curve across the whole speed range. Piston machines add torque pulsation and a flywheel requirement.
Send us the compressor type, absorbed power and gas data. We select the motor, drive and coupling, and quote them with the torque curve and the starting voltage drop confirmed.
What we need from you to select this drive
The more of this you send, the faster and more accurate the selection. If you only have part of it, send what you have — we will tell you what is still missing.
Duty data and site conditions
| Compressor type | Screw, piston, centrifugal or axial, with the model |
|---|---|
| Absorbed power | Shaft power in kW at the rated duty point, and at the worst-case condition |
| Speed | Operating speed in rpm and the speed range if variable |
| Gas | Gas composition, suction and discharge pressure, flow, suction temperature |
| Torque curve | Starting torque requirement and the torque across the speed range |
| Power supply | Voltage, frequency, short-circuit capacity, permitted voltage drop on start |
| Duty | Continuous or intermittent, unloading method, turndown requirement |
| Site conditions | Ambient temperature, altitude, indoor or outdoor, hazardous area classification |
How we select it
- 1
Confirm the absorbed power at the rated duty point and at the worst-case operating condition.
- 2
Match the motor torque curve to the compressor across the full speed range, including the breakaway torque.
- 3
Check the starting voltage drop against the network short-circuit capacity.
- 4
Select the coupling for the torque, speed and any misalignment or axial float.
- 5
Select the drive or starter and quote the package with the ratings and the voltage drop stated.
Selection points that decide the outcome
Match the torque curves
The motor torque curve has to sit above the compressor requirement at every speed, not just at the rated point. This is critical for centrifugal machines.
Piston machines pulsate
Reciprocating compressors produce torque pulsation that the flywheel and coupling have to absorb. Confirm the flywheel inertia and the coupling type together.
Medium-voltage starting
Large compressor motors are often started direct-on-line or with a medium-voltage soft starter or drive. Confirm the network short-circuit capacity first.
Unloading and turndown
A VSD can replace inlet throttling and unloader steps, but the turndown has to be checked against surge and minimum flow limits.
Hazardous area
Gas compression often falls in a classified area. State the zone so the motor and terminal box are specified correctly.
An indicative package
An example of how a selection comes together. Your figures will differ — this is to show the level of detail we return with a quotation, not a fixed configuration.
Duty
Screw compressor · 250 kW · 6 kV · continuous duty · outdoor, 45 °C
Package
- Motor: 250 kW medium-voltage motor, 6 kV, rated with margin above the worst-case absorbed power
- Starting: medium-voltage soft starter or Innomotics Perfect Harmony GH180 drive, confirmed against the network short-circuit capacity
- Coupling: Flender ARPEX or N-EUPEX coupling selected for the torque, speed and misalignment
- Control: capacity control via VSD where the turndown allows, with surge and minimum flow checked
- Protection: winding and bearing temperature monitoring, vibration monitoring on the compressor train
What we supply for this duty
Medium-voltage motors
- Innomotics SIMOTICS medium-voltage motors and HV series
- WEG M line and S line medium-voltage motors
- ABB medium-voltage motors
Medium-voltage drives
- Innomotics Perfect Harmony GH180, 2.3 – 11 kV / 0.12 – 25 MW
- ABB ACS580MV, ACS6080 and ACS8080
- WEG medium-voltage drives
Low-voltage drives
- Siemens SINAMICS G120X and G150
- ABB ACS580 and ACS880
- WEG CFW11 and CFW701
Couplings and gearboxes
- Flender ARPEX, N-EUPEX and ZAPEX couplings
- Flender gear units for speed-increasing compressor drives
- Flender FLENDER ONE
Control and monitoring
- Siemens SIMATIC S7-1500 and ET 200
- B&R X20 system
- Vibration, surge and temperature monitoring
Ratings we can supply
Typical ratings available
| Motor power | Low-voltage to multi-megawatt medium-voltage |
|---|---|
| Medium-voltage drive | Innomotics Perfect Harmony GH180: 2.3 – 11 kV, 0.12 – 25 MW |
| Speed | Matched to the compressor; speed-increasing gear units available for centrifugal machines |
| Starting | Direct-on-line, soft starter, or medium-voltage drive, per the network capacity |
| Duty | Continuous duty is standard; state the unloading and turndown requirement |
Brands we supply
Browse by category
Related applications
Other Brands Available on Request
Beyond the brands shown here, we also source and supply spare units and parts for most international and Chinese industrial brands. Not sure what you have? Send us a photo of the nameplate — we will identify the unit and quote the original part.
Why work with us
- We select the whole drive train — motor, gear unit, coupling, starter and brake — as one matched package.
- You send the duty data; we return the ratings, service factors and alternatives in writing.
- We supply Siemens, Innomotics, Flender, ABB, WEG and B&R, so selection follows your duty, not one catalogue.
- Spare parts and replacements for the same units are available afterwards.
Service & support
Remote and on-site support available, from installation supervision to commissioning and troubleshooting.
What we need from you to quote
For replacements, send a nameplate photo — we identify the exact unit and quote the original part.
- Duty data — power, torque, speed, flow or head, and duty cycle
- Supply voltage, frequency and starting method
- Preferred brand, and your required delivery window
- Quantity, destination port and required delivery date
Answers before you ask
Frequently asked questions
Can you supply a medium-voltage compressor drive package?
Yes. We supply medium-voltage motors, medium-voltage variable speed drives including the Innomotics Perfect Harmony GH180 range from 2.3 to 11 kV, and the matching coupling and controls.
What do you need to select a compressor drive?
The compressor type, absorbed power at the rated and worst-case conditions, speed range, gas data and the network short-circuit capacity. With those we can confirm the torque curve and the starting voltage drop.
Do you only supply the eight brands shown on your homepage?
No. We source and supply spare units and parts for most international and Chinese industrial brands, not only the eight brands shown on this site.
I do not know the exact model number. Can you still quote?
Yes. Send us a photo of the nameplate and we will identify the exact unit before preparing the quotation for the original part.
Do you supply genuine original manufacturer parts?
Yes. We supply genuine original manufacturer parts. Send us a photo of the nameplate and we can identify the exact unit before quoting, so you do not need to look up a model number.
Do you provide installation guidance, commissioning and after-sales support?
Yes. We provide installation guidance, commissioning support and after-sales support, remotely or on site depending on your project.
What is the delivery time?
Lead time depends on the product and configuration. We confirm the delivery schedule together with the quotation, so you have a firm date before you order.
Which export documents and certificates can you provide?
We can provide applicable CE and ISO documentation, certificates of origin, packing lists and test reports according to the requirements of your destination country.
What payment terms and incoterms do you work with?
We accept T/T and L/C payment, and quote FOB, CIF or EXW terms to suit your project.
Send the duty data and we will select the package
We return a selection with the ratings, service factors and alternates stated — so you can compare before you buy.
Request a Quotation