Ross Hill and NOV SCR house parts — control modules, bridges, phase cells, console boards, contactors and fuses. Send a part number or describe the symptom.
An SCR house takes AC from the engine-generator sets and converts it to controlled DC for the drilling motors. When something in that chain fails, the rig stops. Most of this equipment is decades old, long out of production, and not stocked by mainstream distributors — which is exactly the gap Edmundson Industrial works in.
Independent sourcing, not an authorized distributor. Ross Hill, NOV, and other manufacturer names are used for reference only. We supply new-surplus, used-tested, and reconditioned equipment with condition disclosed before sale.
Most people calling about an SCR house do not have a part number yet — they have a rig that will not do something. These are the common entry points.
| What the rig is doing | Where to look |
|---|---|
| Generator will not build voltage, or hunts under load | Generator exciter PCB |
| Engines bog or black out on simultaneous heavy loads | Power limit controller |
| Drilling motor will not reach speed, or overspeeds | Field supply PCB |
| Handwheel does nothing; console indication disagrees | Driller's console PCB |
| Semiconductor fuse blows repeatedly on one drive | SCR bridge · phase cell |
| Reduced or absent dynamic braking | DWDB grid resistor |
| Drive will not take assignment | AC module · DC module |
These are starting points, not a diagnosis. Symptoms overlap across the control chain — tell us what you are seeing and we will help narrow it before you buy anything.
The cards that regulate the drives. AC modules handle generator-side control and synchronising; DC modules set SCR phase angle and run the current and speed regulation loop for the drilling motors.
| Item | Part number | |
|---|---|---|
| Ross Hill AC Module | 0521-2500 series | View › |
| Ross Hill DC Module | 0522-2400-23 · NOV 6415-2400-21 | View › |
| Power Modules | SCR power module assemblies | View › |
Where generated AC becomes controlled DC. Bridges, phase cells, pucks and the semiconductor fuses that protect them.
| Item | Part number | |
|---|---|---|
| Model 1400 SCR Bridge | 0001-6307-70 | View › |
| Model 1500 Phase Cell | 0100-0150-03 | View › |
| SCR Bay Components | pucks, fuses, snubbers | View › |
Excitation, power limiting and field supply — the loop that keeps the plant stable under drilling load.
| Item | Part number | |
|---|---|---|
| AutoSync AC II Module | 0000-8500-00 | View › |
| Generator Exciter PCB | 0509-7901 | View › |
| Power Limit Controller PCB | 0509-7497 | View › |
| Field Supply PCB | 0509-1300 | View › |
The operator interface and the protective functions behind it.
| Item | Part number | |
|---|---|---|
| Driller's Console PCB, PC1 | 0509-2500 | View › |
| Sprocket Slip PCB | 0509-2600 | View › |
| DWDB Grid Resistor Assembly | 0100-1000-04 | View › |
This page covers replacement parts. If you are sourcing or evaluating a complete system, start at SCR Houses — including the used-house buying guide and SCR vs VFD, Model 1400, Model 1500, and rebuild & retrofit.
NOV retained most Ross Hill numbering after acquiring the line. The DC control modules are the main exception. Our Ross Hill / NOV cross-reference lists what we have confirmed, flags what we have not, and calls out the numbers that look interchangeable but are not.
Condition always disclosed before sale. Photos on request. Same-day response on most requests.
Condition disclosed before sale. Same-day response on most requests.