Atlas Copco ZT 50 VSD⁺ (FF) Oil-free Tooth Air Compressor

The Atlas Copco ZT 50 VSD⁺ is the top air-cooled point of the ZR/ZT 30-50 VSD⁺ oil-free tooth compressor family, and it earns that position with an architecture the smaller steps of the family repeat but never exceed: two in-house NEOS Next frequency converters, each paired with its own IE5 ultra-premium permanent magnet motor. One motor drives the low-pressure tooth element and the other drives the high-pressure element, every element gets exactly the speed it needs, and the whole train stays direct coupled from motor shaft to element shaft.

Published at 8.6 and 10 bar(e) with three measured points per class, the machine closes the family flow ladder at 153.7 l/s on a 50 kW power rating, and it brings an integrated dryer option into the same canopy so treated air leaves the frame without a separate treatment skid.

Two Converters and Two Motors on the ZT 50 VSD⁺

Each NEOS Next converter carries a main drive for its motor plus an auxiliary drive, and the auxiliary drive runs the cooling fan and the dryer supply. The converters are rated IP54 and hold operation stable up to 50°C / 122°F ambient, which keeps the machine a candidate for unconditioned compressor bays. The permanent magnet motors are oil-cooled inside the compressor’s own oil circuit, carry IP66 protection, and never need bearing re-lubrication in service.

Because the two converters split the load at every running condition, the ZT 50 VSD⁺ tracks a demand band from 28 to 100% of maximum capacity — a turn down of 72% — without stepping into unload power waste, and Atlas Copco lists energy savings of up to 35% against fixed-speed operation on this family.

Six Published Points Across the Two ZT 50 VSD⁺ Classes

The specification sheet prints each pressure class as a Minimum row at 4 bar(e), an Effective row at 7 bar(e) on the lower class and 9 bar(e) on the higher class, and a Maximum row at rated pressure. All six rows are driven by the same 50 kW (67 hp) power rating, and the work-station sound level is listed at 70 dB(A) for both classes.

Both Minimum rows open identically at 40.4–153.7 l/s and 2.4–9.2 m³/min, so the class you choose decides the top of the pressure travel rather than the start of it. The 8.6 bar(e) class closes at 144.5 l/s and 2.8–8.6 m³/min at Maximum — the sheet prints the Maximum flow floor at 47.2 l/s, above the Effective row floor of 39.3 l/s, and the value is reproduced here exactly as published — while the 10 bar(e) class closes at 130.5 l/s and 2.2–7.8 m³/min for headers regulated near 10 bar(e). In psig the classes read 58 / 102 / 125 and 58 / 130 / 145 across their three points.

A buyer holding a header near 7 bar(e) sizes the install against the Effective row at 147.0 l/s; a plant that runs close to rated pressure reads the Maximum row, and the 14.0 l/s difference between the two class closures is the trade the extra pressure headroom asks for.

Where the ZT 50 VSD⁺ Sits in the 30-50 VSD⁺ Ladder

The air-cooled half of the VSD⁺ family climbs from the ZT30VSD⁺-8.6 at 95.5 l/s to the ZT50VSD⁺-8.6 at 153.7 l/s, and each step keeps the same dual-converter architecture while the flow ceiling rises. The ladder below reproduces the published 8.6 bar(e) Minimum-to-Maximum bands for the air-cooled models, and it shows the ZT 50 VSD⁺ adding 17.9 l/s of top-end flow over the ZT45VSD⁺-8.6 while holding the family’s ID / IMD dryer availability.

Weights, Dimensions and Dryer Builds of the ZT 50 VSD⁺

The family weight table groups the 45 and 50 kW frames together, so the ZT 50 VSD⁺ carries the same three build weights as the step below it: 1373 kg as the Pack build, 1646 kg as the Full Feature build with the integrated MD dryer (iMD), and 1531 kg as the Full Feature build with the integrated refrigerant dryer (iD). The standard frame measures 2005 × 1022 × 1909 mm, and the Full Feature build stretches to 2440 × 1022 × 1909 mm on the same width and height, so a bay sized for a 45 kW unit accepts either build without widening the floor.

Both pressure classes list ID / IMD dryer availability, which lets the dew point specification ride inside the canopy rather than on a separate skid.

Planning a Bay Around the ZT 50 VSD⁺

Air cooling keeps the install simple: the frequency-controlled fan matches cooling air to every running condition, and the soundproof canopy holds the work-station level at 70 dB(A), measured as the A-weighted sound pressure at the work station under ISO 2151:2004 with the ISO 9614/2 scanning method. Inside the frame, the oil that cools the motors and lubricates the gears circulates through its own circuit and never touches the compressed air, which is how the machine keeps its oil-free Class 0 air promise.

The Elektronikon Touch controller runs the regulation and logs the operating data, and a SMARTLINK connection adds energy reporting and early-warning diagnostics for plants that track consumption per shift. For a night-shift demand that sits far below the day profile, compare that floor against the 36.9 l/s of the 10 bar(e) Maximum row — the drive follows the band, but it cannot print flow below the published floor.

Questions Buyers Ask About the ZT 50 VSD⁺

Why does the 8.6 bar(e) Maximum row start at 47.2 l/s? That is the printed value: at rated pressure the sheet lists the flow band as 47.2–144.5 l/s and 2.8–8.6 m³/min, with the floor sitting above the Effective row floor of 39.3 l/s. Buyers regulating close to 8.6 bar(e) should therefore check their minimum demand against 47.2 l/s, and those with lighter part-load flow read the Effective or Minimum rows instead.

What does the 72% turn down mean for part-loaded shifts? The ZT 50 VSD⁺ regulates between 28 and 100% of maximum capacity, so a line drawing a third of the 153.7 l/s top edge still runs inside the controlled band instead of spilling into unload. The two converters adjust each element separately, which is what keeps net pressure stable across that travel.

Which dryer build fits a 1022 mm bay? All three build weights share the same width and height, and the standard Pack build measures 2005 mm long against 2440 mm for the Full Feature builds. If the dew point must live inside the machine, the iD and iMD builds add the dryer at 1531 kg and 1646 kg respectively and stretch the frame by 435 mm in length.

Stepping Up from the ZT 50 VSD⁺

Demand that outgrows the 153.7 l/s ceiling of the ZT 50 VSD⁺ moves to the standard VSD flagship of the oil-free tooth line, the Atlas Copco ZT 55 VSD, whose 8.6 bar(e) class closes at 138.8 l/s and reaches 143.7 l/s at Minimum on a 55 kW motor. Send your measured demand profile with the pressure your header actually holds, and the quotation will land on the machine and class that match the plant instead of the nameplate.