Drilling Rig Electrical · DC control
Ross Hill 0521-2400-21 — DC Control Module
A number that appears in our records reading 0521 where the rest of the DC control family reads 0522 — and which we have not confirmed either way.
A number that appears in our records reading 0521 where the rest of the DC control family reads 0522 — and which we have not confirmed either way.
Independent sourcing, not an authorized distributor. Ross Hill, NOV, and other manufacturer names and part numbers are used for reference only. Supplied as new-surplus, used-tested, or reconditioned, with condition disclosed before sale.
| Part number | 0521-2400-21 |
|---|---|
| Manufacturer | Ross Hill / NOV |
| EI reference | EI-0521-2400-21 |
| System | Ross Hill / Hill Hayes / NOV SCR drilling |
| Module type | DC control |
| Status of this number | Unresolved — reads 0521 where the rest of the DC family reads 0522. We have not confirmed whether this is a distinct variant. |
| Closely related | 0522-2400-21 (DC control module, standard; NOV 6415-2400-21) |
| Condition | New-surplus, used-tested, reconditioned |
0521-2400-21 · 0521240021 · 05212400 21 · 0521-2400 · 2400-21 · Ross Hill DC control module · RHCC DC module · EI-0521-2400-21
Because the number is real in our records, and pretending otherwise would send a buyer down the same dead end twice. Somebody is holding a board, or a purchase record, that reads 0521-2400-21. They search it, find nothing, and conclude the part is unobtainable.
It is not unobtainable. It is either the same item as the 0522-2400-21 recorded under a transposed prefix, or it is a genuinely distinct variant. We have not confirmed which, and we will not publish a specification we have not verified. What we can do is tell you plainly that both forms exist in our records and help you resolve it at the board.
The DC control modules in this equipment are otherwise consistently numbered 0522-2400-xx, and the AC control modules are numbered 0521-2500-xx. A DC module reading 0521 sits on the wrong side of that split.
Two readings are possible and we are not going to pick one for you. It may be a transcription artefact that entered inventory records and propagated. It may be a real number from a period or configuration we have not documented. Either way the resolution is the same: photograph the board rather than assuming either way.
| Number | What our records describe | Relationship |
|---|---|---|
| 0521-2400-21 | DC control module. Reads 0521 where the rest of the DC family reads 0522. We have not confirmed whether this is a distinct variant. | This page — unresolved |
| 0522-2400-21 | DC control module, standard. NOV 6415-2400-21. The one confirmed case where NOV assigned its own number. | Same dash suffix, documented |
| 0522-2400-23 | DC control module, regulation. Sets SCR phase angle from the driller’s handwheel setpoint. | Different variant |
| 0522-2400-27 | DC control module, series type, with 1K ohm resistor. | Different field configuration |
| 0522-2400-00 | DC control module, shunt type. Also recorded as 0522-2500-00 — a separate known numbering discrepancy on that item. | Different field configuration |
| 0521-2500 | AC control module (RHCC) — the base family number on the AC side, where a 0521 prefix is expected. | Different function |
Read the label, photograph it, and send us both the number and the photo — do not order against either form from a spreadsheet. This item is the clearest case on the site where paperwork and hardware can disagree, and where the hardware is right.
If it turns out your board reads 0522-2400-21, that item is fully documented on its own page, including the NOV 6415-2400-21 equivalent. If it genuinely reads 0521-2400-21, tell us — a confirmed sighting is how this entry stops being unresolved.
Starting from a symptom — a gate firing pulse failure, a misfire, phase loss, one leg dead? The SCR Drive Fault Finder maps what you are seeing to the suspect module and part number.
We will not tell you these two numbers are interchangeable. Across these families a dash suffix can mean a frequency, an engine calibration, a motor field configuration, or a coil voltage, and a prefix group is not a lesser thing than a suffix. A derived number is a lead to check, not an answer.
That is the same standard we apply to the rest of the catalogue. Where we are confident we say so; where we are not, we say that instead. See the Ross Hill / NOV cross-reference for the full set of numbers that are easy to confuse in this equipment.
These are the details that let us identify the right unit instead of guessing at it.
Supplied as new-surplus (unused, from the secondary market), used-tested, or reconditioned, with condition disclosed before sale and photos on request. Availability on legacy Ross Hill and NOV equipment changes constantly — send the number and we will tell you what we can actually find.
Condition always disclosed before sale. Photos on request. Same-day response on most requests.
Send the label photo and we will tell you which item you are actually holding.