Ross Hill AC Control Module

The AC firing and protection module in Ross Hill and NOV SCR drilling systems: part 0521-2500-14. Surplus, replacement, and cross-referenced.

The 0521-2500-14 is the AC control module in Ross Hill and NOV SCR drilling systems: it generates the SCR gate-firing signals and handles assignment and protection for the drive. Edmundson Industrial sources it new old stock, surplus, used-tested, and reconditioned. Send the 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. Condition is disclosed before sale.

Status

Part number	0521-2500-14 (also seen as 521250000)
System	Ross Hill / Hill Hayes / NOV SCR drilling
Module type	AC control: firing and protection
Frequency on file	50 Hz: verify against your set
Function	Generates SCR gate-firing signals; drive assignment and protection
NOV equivalent	Number carried forward (verify against the label)
Pairs with	DC control module 0522-2400-23
Condition	New old stock, surplus, used-tested, reconditioned

Verify the exact dash number and revision against the module label before ordering.

Where it sits in the SCR system

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.

The 0521-2500 AC control family

The AC control modules were built in variants. The dash suffix carries the configuration, frequency, and in at least one case a reverse power relay, so the suffix matters as much as the base number. A module from the same family is not automatically a replacement.

Number	Part description	Relationship
0521-2500-14	AC control module, 50 Hz. Runs as a matched pair with the DC regulation module. Also seen as 521250000.	this page
0521-2500	AC control module (RHCC), the base family number. SCR gate firing, drive assignment and protection.	Base number
0521-2500-32	AC control module. Variant not yet characterised.	Different variant
0521-2500-19	AC control module with reverse power relay. Physical-label confirmation required before ordering.	Match exact suffix and feature set
0521-2500-35	AC control module, 50/60 Hz. Physical-label confirmation required before ordering.	Match suffix and frequency

Note the frequency split in particular. If your set runs 60 Hz and the module in front of you is recorded as a 50 Hz variant, stop and confirm before fitting it. Send the full dash number and the frequency and engine configuration of the set, and we will match the variant rather than guess.

Condition and sourcing

RHCC 0521-2500-14 is quoted only after current availability, condition, and lead time are confirmed. Any offered unit is identified as new-surplus, used-tested, or reconditioned before sale.

If the observed failure does not line up with RHCC 0521-2500-14, use the SCR Drive Fault Finder to narrow the subsystem before requesting a part.

Identification checkpoint

For RHCC 0521-2500-14, confirm function: Generates SCR gate-firing signals; drive assignment and protection; module type: AC control: firing and protection; frequency on file: 50 Hz: verify against your set. Use the installed label and complete suffix before treating another item as equivalent.

FAQ

What is the Ross Hill AC control module?

It is the AC control board in a Ross Hill / NOV SCR drilling drive, part 0521-2500-14. It generates the SCR gate-firing signals and handles drive assignment and protection.

Is the Ross Hill AC module the same as the NOV AC module?

In most cases yes. NOV carried the Ross Hill AC numbering forward, so 0521-2500-14 is typically the same part. We verify against the label before quoting.

What is the difference between the AC and DC module?

The AC control module handles firing and protection; the DC control module handles regulation, setting the SCR phase angle from the handwheel setpoint. They work together as a pair.

Can you supply a replacement?

Yes. We source 0521-2500-14 as new old stock, surplus, used-tested, and reconditioned, with condition disclosed before sale.

Request a Quote

or send the part number to sales@edmundsonindustrial.com · (832) 975-8827 · Houston, TX. Response timing is confirmed with the request.

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