Description
The Siemens 6DD1683-0CD5 is the SP23.5 Power Supply Unit within the SIMADYN D / SIMATIC TDC ecosystem—a 125 W, forced-air-cooled rack PSU that delivers 5 V DC @ 25 A to the backplane (feeding T400/FM458 processor boards and communication modules), plus ±15 V DC for analog-front-end circuits and +24 V DC for relays, fans, and auxiliary loads. With dual-range AC input (115 / 230 V AC, 50/60 Hz) and wide DC-input tolerance, the 6DD1683-0CD5 is engineered for the electrically noisy, thermally stressed environments of rolling-mill drive shacks and power-plant turbine decks where a single PSU failure can stall an entire TDC rack—and with it, the main drives of a multi-stand mill. Siemens placed the SP23.5 into PM500 “Discontinued – Deleted Without Replacement” effective October 1, 2017, making verified NOS and functionally tested pulled units the only supply path for the thousands of SIMADYN D / TDC racks still earning worldwide.
Application Scenarios
In a Southwest U.S. copper-rod rolling line, the 12-stand breakdown + finishing train is controlled by a SIMATIC TDC rack housing two FM458-1 motion CPUs, three EXM448 comm cards, and four T400 technology modules—all drawing from a single 6DD1683-0CD5 SP23.5 in Slot 1 of the 19″ subrack. During a summer heatwave, the mill’s MCC room hit 54 °C; the SP23.5’s intake fan bearing started rattling, and three days later the 5 V rail dipped to 4.78 V during a roll-change acceleration spike, tripping the TDC’s backplane watchdog and dropping the entire train—22 minutes of downtime, ~$18k in lost rod. The plant’s spare-bank audit revealed they’d never stocked a spare PSU (“it’s just a power supply, how can it fail?”). They sourced a tested 6DD1683-0CD5 overnight, swapped it in during the next scheduled PM (15 minutes, four captive screws + backplane connector), and added a “2-hot-swap-spares per rack” rule. Eighteen months on, a second SP23.5 in a sister line did show the same fan-whine precursor—this time they swapped before the trip, zero unplanned stop. In SIMADYN D land, the 6DD1683-0CD5 isn’t glamorous, but it’s the rail that everything else hangs on.
Parameter
| Main Parameters | Value / Description |
|---|---|
| Product Model | 6DD1683-0CD5 |
| Manufacturer | Siemens (SIMADYN D / SIMATIC TDC) |
| Product Category | Power Supply Unit (SP23.5 type) |
| Rated Output Power | ~125 W |
| Main Output | 5 V DC @ 25 A (backplane logic, low ripple) |
| Aux. Output 1 | +15 V DC (analog front-end circuits) |
| Aux. Output 2 | –15 V DC (analog front-end circuits) |
| Aux. Output 3 | +24 V DC (relays, fans, limited current) |
| Input Voltage | 115 / 230 V AC (50/60 Hz); wide-range DC also supported |
| Efficiency | > 85 % (typical) |
| Cooling | Forced air (built-in temp-controlled fan) |
| Protection | OCP / OVP / OTP / Short-circuit |
| Indicators | LED: 5 V OK, 24 V OK, FAULT, Fan Status |
| Operating Temp. | 0 … +60 °C (derating to +70 °C) |
| Dimensions (H × W × D) | 130 × 250 × 340 mm (Eurocard, multi-slot width) |
| Weight | ~4.3 kg |
| Lifecycle | PM500 Discontinued (Oct 1, 2017, no replacement) |
Technical Principles and Innovative Values
- Innovation Point 1: 5 V @ 25 A Backplane Rail Purpose-Built for Compute Boards. Generic SITOP PSUs stop around 10 A on 5 V—insufficient for a TDC rack stuffed with FM458 + T400 + EXM448, which collectively draw 12–18 A even at idle. The 6DD1683-0CD5 sizes the 5 V rail to 25 A specifically for this “processor-dense” backplane load, with tight line/load regulation (< ±1 %) so that high-speed CFC task cycles on the T400 don’t suffer voltage-drop-induced watchdog trips.
- Innovation Point 2: Triple-Output Architecture in One Brick. Most rack PSUs give you 5 V + 24 V and call it done. The 6DD1683-0CD5 adds clean ±15 V rails for the analog sections of connected I/O and technology modules—meaning the T400’s 12-bit AI (±10 V) and SSI LVDT front-end get a quiet reference without a separate analog-supply brick. Three outputs, one fan, one set of AC terminals.
- Innovation Point 3: Diagnosable LED Set + Forced-Air Longevity. The front-panel LEDs (5 V OK, 24 V OK, FAULT, Fan) let a mill electrician diagnose “is it the PSU or the backplane?” in 10 seconds without a PG. The thermostatically controlled fan spins up only when the heatsink demands it—extending bearing life in the dusty drive-shack environment where many SP-series units die of fan seizure, not capacitor failure.
