Cummins QST30-G5

1,000 kW standby diesel genset on the 30.5 L V-12, the Cummins standard at the 1 MW node

Cummins QST30-G5 is one of 10 data center generators tracked in the SecondWatt catalogue, each with specifications, lead times and indicative secondary-market pricing.

Cummins QST30-G5 (DQFAD) genset dossier: 1,000 kW rating, verified specs, used pricing from 175,000 USD versus 349,900 USD new, inspection checklist.

The Cummins QST30-G5 is a 60 Hz G-Drive build of the 30.5 L V-12 QST30 (140 x 165 mm, twin-turbo, Quantum full-authority electronic injection at 1,100 bar), powering the DQFAD genset at 1,000 kW standby and 900 kW prime. Gross engine output runs 1,112 kWm standby at 1,800 rpm, burning 272.3 L/hr at full standby load, with PowerCommand controls, UL 2200 listed packages, and EPA Tier 2 emergency certification; the Tier 4 Final node is the DQFAH package. DQFADs carry 1 MW standby duty at data rooms, hospitals, and industrial plants, competing head-on with the CAT C32. Fleet standardization on PowerCommand electronics and the nationwide Cummins distributor network keep the model on repeat-buyer shortlists. The used market is priced but compressed: a 10,921-hour 2007 unit asked 307,900 USD against 349,900-350,000 USD for new units, meaning used asks ran 85-90% of new money in the 2026 supply crunch. Low-hour units at 175,000 USD (2015, 263 hours; 2021, 6 hours) show the bid-ask dispersion buyers can still exploit.

Why it matters

The QST30 shows the 2026 market's compression at its starkest: used asks at 85-90% of new pricing, the clearest arbitrage signal in the category for sellers, and a warning marker for buyers. A published new-unit anchor near 350 USD per kW makes this one of the few nodes where new, surplus, and used pricing can be laddered precisely.

Who buys it

Data rooms, hospitals, municipalities, and industrial plants buy DQFADs at the 1 MW node; fleet standardization on Cummins electronics drives repeat buyers. The trigger is the 52-70 week new-unit queue: with new units at 349,900 USD, tested used units at 175,000 USD clear fast, and even high-hour units command near-new money.

Role in the data center

Standby engine-generator at 1,000 kW behind the ATS for mid-size data rooms, or distributed N+1 rows where 1 MW blocks simplify sparing.

Key specifications

Technical summary

DQFAD standby / prime: 1000 / 900 kW Engine: QST30, 30.5 L V-12, twin turbo Bore x stroke: 140 x 165 mm, CR 14.7:1 Gross standby: 1112 kWm at 1800 rpm Fuel system: Quantum electronic, 1100 bar Fuel, standby 100%: 272.3 L/hr Fuel, prime 100% / 75% / 50%: 248 / 185 / 126 L/hr Voltage: 277/480 V typical, PMG excitation Engine dry weight: 3565 kg Emissions: EPA NSPS Tier 2, stationary emergency Controller: PowerCommand 3.3 (current), PCC 3201 earlier Certifications: UL 2200 listed package

Configurations and options

Used units appear open, in Level 2 sound-attenuated enclosures, and enclosed with 2,000 gal class UL 142 tanks (a documented 2019 build weighed 35,202 lbs in that form). Options: PowerCommand 3.3 paralleling, PMG alternators at 277/480 V, jacket water heaters, and battery chargers.

Compatibility and dependencies

Pairs with 1,250 kVA-class ATS gear, day tanks, and 480 V switchboards. Quantum electronics diagnose through Cummins InPower tooling; Tier posture (DQFAD Tier 2 versus DQFAH Tier 4F) governs siting in strict districts. Cummins distributor coverage is nationwide.

Pricing and availability

Published price range: $175,000 – $307,900. Trend: up Dealer guide bands from 2026 put DFHA units at 70,000-130,000 USD, DFHD at 90,000-150,000 USD, and DQFAD Tier 2 at 110,000-200,000 USD. The observed 2026 market ran ahead of all of them: 175,000 USD for low-hour units, 307,900 USD for a 10,921-hour unit (85-90% of the 349,900- 350,000 USD new-unit anchor), evidence of queue-driven compression between used and new. Lead time, new: 52-70 weeks. Lead time, used or refurbished: 2-8 weeks. Warranty, used: 30-day dealer typical; new units carry factory terms.

Lifecycle and maintenance

Published service economics: annual service 2,500-5,000 USD, load-bank testing 1,500-3,000 USD per year, with top-end and in-frame overhauls described as five-figure events spaced years apart under standby duty. Aftercooler and cooling-system care are flagged longevity drivers. Cummins does not publish QST30 overhaul-hour intervals; dealer assessment governs, and documented service history materially moves resale value.

Common failure points

• Fuel injectors — Fouling and rough running on degraded standby fuel
• Twin turbochargers — Shaft play and oil leaks on high-hour units
• Aftercooler and cooling — Thermal stress on neglected cooling systems
• Quantum ECM and sensors — Fault codes and derates from aging sensors
• Generator-end insulation — Low megger readings after storage

Inspection checklist

Package identification — DFHA/DFHD legacy versus DQFAD Tier 2 versus DQFAH Tier 4F; bands differ by 100,000+ USD Hours — verify meter; observed bench spans 6 to 10,921 hours with price tracking hours loosely in 2026 Overhaul documentation — top-end and in-frame overhauls are five-figure events; require records Injectors — verify service; fuel-quality fouling is the family's documented standby failure driver Twin turbos — inspect both for shaft play and oil leaks Quantum electronics — read fault history through InPower; verify ECM firmware support Oil analysis — trend 2 samples; copper flags bearings, silicon flags filtration Coolant — verify service history; aftercooler and cooling care are flagged longevity drivers Generator end — megger stator; below 5 megohms warrants rewind pricing Controls — PCC 3201 versus PC 3.3; paralleling config verified against destination switchgear Emissions nameplate — confirm Tier 2 emergency certification; DQFAH aftertreatment condition where fitted Batteries — replace banks past 4 years; test both starters Enclosure and tank — verify UL 142 certification and containment Load test — 4-hour run to 1,000 kW at temperature; annual load-bank history (1,500-3,000 USD/yr) in records Records — complete service logs; annual service runs 2,500-5,000 USD and gaps reprice the unit

Regional notes

60 Hz US supply dominates (the G5 is a 60 Hz build); 50 Hz nodes are served by QST30-G3/G4 builds in export markets. No 50 Hz QST30 stock observed in US channels. Tier posture splits California-bound value.