Drilling Rig Electrical

Ross Hill Controls and the Hill Hayes SCR designs (now NOV) powered a generation of drilling rigs. Edmundson Industrial sources the control modules, SCR bay parts, and power that keep those systems running, and cross-references Ross Hill and NOV numbering both directions. Send the part number and we'll tell you what we can find.

Independent sourcing, not an authorized distributor. Ross Hill and NOV are trademarks of their respective owners, used for reference only. We supply new old stock, surplus, used-tested, and reconditioned, with condition disclosed before sale.

How a Ross Hill / NOV SCR system works

AC input	Bus from diesel engine–generator sets, commonly 600 V AC
Conversion	Phase-angle-controlled SCR (thyristor) AC-to-DC
DC output	0–750 V DC, stepless
Per-SCR current	about 1600 A continuous, typical
Assignable to	Drawworks, mud pumps, and rotary table
Control	AC firing / assignment module plus DC regulation module (handwheel / throttle setpoint)

Typical SCR drilling-system values; configurations vary by rig. Verify against the equipment.

DC drilling motor it drives

Motor	GE752 high-torque DC drilling motor (industry standard)
Rated voltage	750 V DC
Rated current	about 1185 A
Power	about 1130 HP (200–1200 kW range)
Construction	12-pole, brush-type DC
Base speed	about 1040 RPM
Cooling	Separately-driven blower (about 2800 SCFM)

Typical GE752 ratings shown for reference; verify against the motor nameplate.

Common Ross Hill / NOV part numbers

Part number	EI reference	Description
0521-2500-14	EI-0521-2500-14	AC control module (firing / protection) — also seen as 521250000
0522-2400-23	EI-0522-2400-23	DC control module (regulation)
0522-2400-21	EI-0522-2400-21	DC module = NOV 6415-2400-21
6702ED584	EI-6702ED584	Eaton / Cutler-Hammer contactor used in the SCR bay

Drilling electrical we source

Part	Notes	Go
AC Control Module	Firing and protection — 0521-2500-14	AC module ›
DC Control Module	Regulation — 0522-2400-23 / NOV 6415-2400-21	DC module ›
SCR Bay Components	Contactors, blowers, panel meters, instrumentation	SCR bay ›
Power Modules	SCR power stacks and DC drive stacks	Power modules ›
Cross-Reference	Ross Hill ↔ NOV numbering	Cross-reference ›

Condition & sourcing

We supply Ross Hill and NOV drilling parts as new, new-surplus, used-tested, and reconditioned, with condition disclosed before sale and photos on request. We are an independent surplus and sourcing company, not an authorized distributor.

FAQ

Are Ross Hill and NOV parts the same?

Often yes. NOV kept most Ross Hill numbering when it acquired the line, with the DC modules the main exception, where distinct 6415- numbers appear. We verify before quoting.

Can you supply obsolete or discontinued modules?

Yes. AC and DC control modules, SCR bay components, and power stacks are sourced as new old stock, surplus, used-tested, and reconditioned. Condition is disclosed before sale.

Do the AC and DC modules work as a pair?

Yes. The AC control module handles firing and protection while the DC control module handles regulation; they operate together in the SCR drive. Send both numbers and we match the set.

Where are you located?

Houston, Texas, on the Gulf Coast, and we ship to rigs and yards wherever they are.

Request a Quote

or send the part number to sales@edmundsonindustrial.com · (832) 975-8827 · Houston, TX. Same-day response on most requests.