The AutoSync AC II module from Ross Hill / NOV SCR generator control — the card that brings an incoming generator into synchronism before it is paralleled onto the bus.
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 | 0000-8500-00 |
|---|---|
| Manufacturer | Ross Hill / NOV |
| EI reference | EI-0000-8500-00 |
| Stock code | EL25-8500-00 |
| System | Ross Hill / Hill Hayes / NOV SCR drilling |
| Function | Generator synchronising |
| Condition | New-surplus, used-tested, reconditioned |
0000-8500-00 · 0000850000 · 00008500-00 · 0000-8500 · 8500-00 · Rev C · Rev E · AutoSync · Auto-Sync · Auto Sync · AutoSync AC II · AC Module Auto Sync · EI-0000-8500-00 · EL25-8500-00
On a diesel-electric rig, generators are paralleled onto a common bus as load demands. Before a set can be closed onto that bus, its voltage, frequency, and phase angle have to match what is already there. The AutoSync AC II module is the control that performs that match and permits the close.
When it degrades, the symptom is operational rather than electrical: a set that will not come online, takes a long time to sync, or closes roughly. Rough closure is the one to take seriously — paralleling out of phase is mechanically violent and expensive.
Most people reach this page from a symptom rather than a part number. These are starting points for diagnosis, not a substitute for it.
| What you are seeing | What it usually indicates |
|---|---|
| Generator will not synchronise or come onto the bus | Sync permissive not being issued |
| Sync takes far longer than it should | Matching loop degraded or drifting |
| Hard or rough closure when paralleling | Out-of-phase closure risk — stop and investigate before repeating |
| Set syncs on one unit but not another | Compare modules and dash suffixes across sets |
| Intermittent behaviour that worsens with vibration | Check card-edge connectors before condemning the card |
| Number | What it is | Substitute? |
|---|---|---|
| 0000-8500-00 | AutoSync AC II module, base number. Rev C and Rev E both confirmed in service. | baseline |
| 0000-8500-18 | Same module family, different engine calibration — recorded against CAT 3512B, 1200 RPM, 600 V 3-phase 60 Hz, 183 flywheel teeth, 199.4 µsec, mag pickup 3660 Hz @ 1200 RPM, PMG 240 VAC 120 Hz 1-phase. | NOT a substitute |
| 0001-2657 | AC Module Auto Sync Aux II PCB — the auxiliary card inside the assembly, and frequently the item that actually failed. | Different item |
| 0001-2656-00 | 3-phase AC control module, EMD engine applications. | Different engine family |
The dash suffix on this module family is an engine calibration, not a revision level. A -18 will physically fit where a -00 came out and will not sync correctly, because it is matched to a different engine, flywheel tooth count, and pickup frequency. Confirm the full dash number, the revision, and the engine the unit was calibrated for before ordering.
We verify the exact dash number and revision against the physical unit before quoting, and we send photos of the plate on the unit being offered. Send a photo of your nameplate, or type out what it reads, and we will match the revision rather than guess 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.
Condition disclosed before sale. Same-day response on most requests.