Description
The Atlas Copco GA 55 VSD brings variable speed drive technology to the 55 kW class of the oil-injected screw range. It pairs a proven compression element with an oil-cooled interior permanent magnet motor rated at 55 kW, and the Full Feature branch integrates a refrigerant dryer inside the same upright package. The machine covers a working pressure band from 4 to 12.5 bar, with free air delivery between 26 and 189 l/s depending on the pressure setting and the air demand at the moment. A standard package of 900 kg and a sound level of 67 dB(A) make it the lightest and quietest machine in the GA 37-110 VSD+ platform above the GA 45.
The machine belongs to the GA 37-110 VSD+ platform, which applies one design logic across the whole power band: the drive slows down when the plant needs less air and speeds up when demand returns. For a plant stepping up from the GA 30-45 class into its first variable speed machine, the GA 55 VSD removes most of the unloaded running that burns electricity without producing air, and it does so inside a frame that fits through a standard machine room door.
Where the GA 55 VSD Fits in the Oil-Injected Range
Atlas Copco positions the GA 55 VSD in the middle of the GA 37-110 VSD+ family, above the GA 37 and GA 45 and below the GA 75. Plants that run a 55 kW fixed speed machine today, or that consolidate several small compressors into one, find in the GA 55 VSD a direct replacement that also carries the energy logic of a variable speed drive. The oil-injected design keeps the element lubricated and sealed by the oil film itself, which suits general industrial air from 4 bar up to 13 bar maximum working pressure.
What the VSD and FF Names Cover
The VSD part of the name refers to the variable speed drive: an in-house designed Neos inverter adjusts the motor speed continuously so the delivered air matches the demand curve of the plant. The FF suffix marks the Full Feature branch, which adds a refrigerant dryer, filtration and an electronic no-loss drain inside the same enclosure. Both branches share the same element, the same motor and the same control platform, so a plant can start with the standard package and move to Full Feature without changing the installation footprint.
Technical Specifications of the GA 55 VSD
The table below condenses the GA 55 VSD into its headline figures:
| Parameter | Value |
|---|---|
| Installed motor power | 55 kW / 75 hp |
| Working pressure range | 4 to 12.5 bar(e), maximum 13 bar(e) / 188 psig |
| Free air delivery | 26 to 189 l/s (55 to 400 cfm) |
| Noise level | 67 dB(A) |
| Weight, standard / Full Feature | 900 kg / 1100 kg |
| Dimensions, Full Feature | 1656 mm wide, 1100 mm deep, 1968 mm high |
VSD+ Flow Range Across the Pressure Band
Each pressure version covers a wide flow window because the drive modulates between a low idle and full speed. The figures below apply to the GA 55 VSD+ in its four settings:
| Working pressure | FAD min-max (l/s) | FAD min-max (m³/h) | FAD min-max (cfm) |
|---|---|---|---|
| 4 bar(e) / 58 psig | 26 – 189 | 93 – 680 | 55 – 400 |
| 7 bar(e) / 102 psig | 26 – 188 | 94 – 677 | 55 – 399 |
| 9.5 bar(e) / 138 psig | 26 – 166 | 93 – 598 | 55 – 352 |
| 12.5 bar(e) / 181 psig | 40 – 140 | 145 – 504 | 85 – 297 |
The figures apply to the 50/60 Hz version of the machine. Unit performance is measured according to ISO 1217, annex E, edition 4:2009, and the FAD is measured at the effective working pressures of 4, 7, 9.5 and 12.5 bar(e). The maximum working pressure is 13 bar(e) / 188 psig. The noise level of 67 dB(A) is the mean value measured at a distance of 1 m at maximum working pressure according to ISO 2151:2004 using the ISO 9614/2 sound intensity method, with a tolerance of 3 dB(A).
The turndown behavior is the heart of the specification. At 4, 7 and 9.5 bar the GA 55 VSD idles down to 26 l/s, which is about one seventh of its full-speed delivery at those settings. During breaks, shift changes and weekend ramps the machine keeps the network pressurized at that low idle instead of blowing off surplus air, and the pressure band stays within the limits the controller defines.
Dimensions and Weight
The upright, compact layout keeps the floor area of the GA 55 VSD small. The standard package measures 1100 mm deep, 1153 mm wide and 1968 mm high, and the Full Feature branch adds width for the integrated dryer to reach 1656 mm, with depth and height unchanged. The standard package weighs 900 kg and the Full Feature branch weighs 1100 kg. Among the machines in this power class, those figures place the GA 55 VSD at the light end of the range, which eases floor loading calculations in older buildings and shortens the installation plan.
A Quiet Upright Package
One Meter of Depth in the Machine Room
Many plants replace an aging compressor without enlarging the compressor room. The GA 55 VSD was laid out vertically for exactly this situation: the package stands tall rather than long, so the installation depth stays at 1100 mm for both branches. A GA 55 VSD that fits into the same bay as the unit it replaces avoids civil work, and the integrated treatment chain of the Full Feature branch removes the need for a separate dryer bay beside the compressor.
67 dB(A) at the Work Station
The GA 55 VSD posts a sound pressure level of 67 dB(A), the lowest figure in the GA 37-110 VSD+ table. Compressor rooms attached to production halls, basement plant rooms below offices and leased buildings with shared walls all benefit from a machine this quiet. The acoustic design keeps the noise at the work station low without sacrificing the cooling airflow that the element and motor need.
The iPM Motor and Neos Inverter
Oil-Cooling and IP66 Protection
The interior permanent magnet motor of the GA 55 VSD exceeds IE5 standards, and it runs oil-cooled: the same oil circuit that lubricates and seals the element also removes the heat from the motor windings. This design keeps the motor compact and protects it against dust and moisture with IP66 pressure-tight sealing, so no cooling air has to be blown through the motor compartment.
IES2 Power Drive Efficiency
The Neos inverter was designed in-house and controls the iPM motor as a matched pair. Together the inverter and motor exceed the IES2 requirements of EN 50598 for power drive efficiency, which means the losses between the mains supply and the compressor shaft stay low across the whole speed range. The inverter carries IP5x protection inside a robust aluminum enclosure, and its heat dissipates in a separate compartment so the electrical components remain cool and their lifetime improves.
How VSD+ Matches Air Demand
Pressure Stability and Turndown
A fixed speed machine reacts to falling demand by loading and unloading, and every unloaded minute consumes power while producing no air. The GA 55 VSD instead adjusts the motor speed so the GA 55 VSD tracks the demand curve of the plant. The pressure band stays where the setpoint is, the machine idles down to 26 l/s when the consumption allows it, and the electricity bill reflects the air actually produced. Variable speed drive technology generates energy savings of up to 50 percent, and the lowered system pressure that VSD+ allows adds further savings because every bar of unnecessary pressure costs energy.
Starting Under System Pressure
The GA 55 VSD can start and stop under full system pressure. The GA 55 VSD needs no network venting before a restart after a weekend shutdown, and no unloading sequence delays the first cubic meter of air on Monday morning. This behavior also allows the machine to act as a trim unit alongside base-load machines without interaction problems on the header.
Full Feature: The Integrated Refrigerant Dryer
The Full Feature branch integrates a refrigerant dryer into the package, sized for the GA 55 VSD so no excess energy is consumed at part load. The dryer holds the pressure dew point between 2 and 3 degrees Celsius at the reference conditions, and the whole treatment chain sits inside the same upright frame. Plants gain dry air at the outlet without piping a second unit, and the layout stays as compact as the compression side.
Condensate Management
Condensate from the dryer and the separator leaves through an electronic no-loss drain, which removes the water without wasting compressed air. The drain is controlled and monitored by the controller, so a blocked or failing drain is reported instead of silently flooding the downstream network.
Monitoring, Control and Connectivity
SMARTLINK and OPC UA
The Elektronikon Touch controller governs the machine and logs the operational parameters. SMARTLINK remote monitoring is standard and reports the operational parameters of the GA 55 VSD to a computer or smartphone, so the service planning is based on real data instead of fixed calendars. OPC UA connectivity integrates the compressor into the production monitoring system as well, which turns the machine into a data point on the factory floor rather than a black box in the corner.
Energy Recovery and Factory Options
A specifically developed energy recovery system can be built into the GA 55 VSD, recovering up to 75 percent of the power input as hot air or hot water. For a plant that heats workshops or process water, the recovered energy offsets a separate heating bill. Further options cover different voltage supplies, cold-weather kits and an oversized dryer for the toughest ambient conditions, so the package can be matched to the site conditions without losing the factory warranty coverage.
Applications of the GA 55 VSD
The GA 55 VSD serves plants whose air demand fluctuates across the day: automotive component shops with lifts and spray booths, food and beverage lines that pause at weekends, plastics processing with cyclical mold changes, and general manufacturing where shift patterns leave long low-load windows. The 4 bar low-pressure setting extends the reach into textile air, glass molding and pneumatic conveying networks that run dedicated low-pressure headers. Workshops that consolidate two or three small fixed speed compressors into one machine also fit the profile, because the wide flow window replaces the cascade control of multiple units with a single modulating machine.
Service and Support Around the GA 55 VSD
The drive train of the GA 55 VSD runs without a gearbox or coupling between motor and element, which removes slippage losses and the associated maintenance items. Service points are arranged for access from the front of the machine, and the electronic components sit in their own compartment away from the hot compressor section.
Atlas Copco fluids and lubricants are tailored to the GA 55 VSD with anti-oxidation additives that hold their protective qualities across the service interval. For the drive motor overhaul scope on the GA VSD+ platform, see the GA VSD+ Motor Overhaul Kit. The installed base of the GA 55 VSD and its Full Feature branches runs across continents, and Seadweer supports the machine with original spare parts, service kits and technical documentation for every configuration.
FAQ
What does VSD+ mean on the GA 55 VSD?
VSD+ is the Atlas Copco designation for variable speed drive generation with an interior permanent magnet motor and the in-house Neos inverter. The motor speed follows the air demand, which removes unloaded running and saves up to 50 percent energy compared with fixed speed operation.
Is the GA 55 VSD an oil-injected machine?
Yes. The element is lubricated and sealed by injected oil in the usual rotary screw manner, and the oil is separated from the delivered air inside the package. The GA 55 VSD belongs to the oil-injected GA 37-110 VSD+ platform.
How much air does the GA 55 VSD deliver?
The flow window reaches from 26 l/s at idle to 189 l/s at full speed on the 4 bar setting. At 7 bar the machine covers 26 to 188 l/s, and at 12.5 bar it covers 40 to 140 l/s depending on the actual demand.
What does FF add to the GA 55 VSD?
The Full Feature branch integrates a refrigerant dryer with a pressure dew point of 2 to 3 degrees Celsius, filtration and an electronic no-loss drain inside the same enclosure. The branch measures 1656 mm wide instead of 1153 mm, while depth and height stay unchanged.
How loud is the GA 55 VSD?
The mean sound pressure level is 67 dB(A), measured at 1 m distance at maximum working pressure according to ISO 2151:2004 with a tolerance of 3 dB(A).
How heavy is the GA 55 VSD?
The standard package weighs 900 kg and the Full Feature branch weighs 1100 kg, which makes the GA 55 VSD the lightest machine in its power class inside the GA 37-110 VSD+ platform.
Ingrid Solberg –
Our compressor room sits directly behind the quality office, so noise was the first question we asked. The GA 55 VSD holds the whole mid-shift load at a sound level we can talk over, and the panel reports the running data to the office computer without any extra hardware. Night production drops to a trickle of air and the electricity meter follows the demand instead of the clock. Seadweer checked our pressure setting against the configuration sheet before the order was placed.