NOV VFD house
What it does
Generators make fixed-frequency power. The motors on an AC drawworks, mud pump, and top drive need variable frequency. The VFD house is the building that does that conversion. It holds the drives, the transformers, the motor-control sections, the cooling, and the interface to the driller’s controls. NOV’s current land line for this building is Drill Force, including the air-cooled LT and LS versions.
Which rig it fits
A house fits the generators and the motors it was built for. There is no single horsepower in the name “VFD house.” A house from a 1,500 horsepower rig will not run a 3,000 horsepower drawworks and three 1,600 horsepower mud pumps without a different drive lineup. Generator count, bus voltage, and which motors are fed are the description that matters.
How to tell it apart
An SCR house is the older DC cousin: it feeds DC motors on a chain-drive drawworks and DC mud pumps. A VFD house feeds AC motors. A generator skid makes power. The house assigns that power. Buying one does not replace the other.
What to check before you buy
Get the one-line diagram and the drive nameplates. Confirm bus voltage, which motors the drives feed, and whether HVAC and the driller’s interface are in the building. Measure the house against the substructure it has to sit on. Transport size is part of the purchase.
Sellers list what they have, so this exact model is not always up. Electrical & Controls is where that kind of equipment is listed.
Ratings that matter
| Equipment | Drilling-rig variable-frequency drive building |
|---|---|
| Function | Feeds AC motors on the drawworks, mud pumps, and top drive |
| Identity | Configured system, not one catalog horsepower |
| Confirm on the package | Generator kW, bus voltage, drive lineup, cooling, and controls |
Compare with
Sources
Catalog ratings are for the published configuration. A used machine can differ by year, upgrade, and nameplate. 9LINE does not inspect equipment or take part in the sale.