In industrial automation, “power” is rarely glamorous, but it is relentlessly judgmental. A cabinet can be filled with premium PLCs, motion controllers, safety relays, and industrial Ethernet gear, yet a momentary voltage dip or a load step can still trigger resets, nuisance faults, and communication dropouts. The Siemens 6EP1337-3BA00 (SITOP PSU100M) exists to make the 24 V DC backbone stable at a scale where many generic supplies start to struggle: 24 V DC at up to 40 A (960 W) from a 120/230 V AC single-phase input.
This model is designed for high-current 24 V distribution in control cabinets that power large PLC/I/O clusters, dense sensor/actuator networks, industrial switches, and auxiliary electronics that must stay online through real-world disturbances. Siemens specifies controlled and galvanically isolated DC output, adjustable output voltage, defined transient response, and selectable protection behavior—details that matter when your load is not a tidy resistor, but a mix of inductive and capacitive devices that create inrush spikes and fast current swings.
A practical note up front: Siemens marks this product as “product phase-out” and lists a successor part number 6EP3337-8SB00-0AY0; Siemens documentation also indicates the newer PSU8200 24 V/40 A platform replaced this older 6EP1337-3BA00 in the SITOP modular product line.
Key Specifications (Technical Overview)
| Parameter | Siemens 6EP1337-3BA00 (SITOP PSU100M) |
|---|---|
| Input supply | 1-phase AC, 120/230 V selectable via wire jumper (not wide-range) |
| Input voltage ranges | 85–132 V (120 V range) / 176–264 V (230 V range) |
| Line frequency | 47–63 Hz (50/60 Hz nominal) |
| Rated input current | 15 A at 120 V / 8 A at 230 V |
| Inrush current limit (25 °C) | 125 A max; I²t 26 A²·s max |
| Recommended feeder protection | 20 A miniature circuit breaker, characteristic C (per datasheet guidance) |
| Hold-up time | 20 ms minimum at rated load (mains buffering at 230 V) |
| Rated output | 24 V DC / 40 A (960 W typical active power) |
| Output adjustment | 24–28.8 V via potentiometer |
| Voltage tolerance / precision | 3% overall tolerance; 0.1% on slow input/load change |
| Ripple / peak | Ripple 60 mV typical (100 mV max); peak 120 mV typical (200 mV max) |
| Efficiency / losses | 88% efficiency; 131 W power loss typical at rated load |
| Dynamic response | Typical 2 ms settling for 50↔100% load step; max 5 ms |
| Protection concept | Short-circuit proof; overvoltage protection < 35 V; selectable short-circuit behavior (constant current or latching shutdown) |
| Indicators | Green LED “24 V OK”; yellow LED overload; red LED latching shutdown |
| Isolation / safety | Galvanic isolation; SELV per EN 60950-1 and EN 50178; Class I |
| EMC / standards | EN 55022 Class B emissions; EN 61000-6-2 immunity; UL/cULus Listed (UL 508 / CSA) |
| Operating temperature | 0–70 °C (natural convection) with derating above 60 °C |
| Terminals | Screw terminals; output 2× “+” and 2× “−” up to 10 mm² |
| Dimensions / weight | 240 × 125 × 125 mm; net weight 2.9 kg |
| Mounting / spacing | DIN rail EN 60715 (35×15); top 50 mm, bottom 50 mm spacing |
Why a 24 V / 40 A supply is a different animal
Moving from 20 A to 40 A is not merely “twice the current.” It changes how you design the cabinet:
1) Voltage drop becomes a first-class problem.
At 40 A, small wiring resistance turns into meaningful voltage loss and heat. The 24–28.8 V adjustment range exists for a reason: it lets you compensate for distribution losses so that remote loads still see an acceptable voltage under peak draw.
2) Selectivity and fault behavior matter more.
When one branch shorts, you want the branch protection to clear without collapsing the whole 24 V bus. Siemens provides a selectable short-circuit behavior: either a constant-current characteristic (around 46 A) or a latching shutdown mode. That selection helps you align the PSU’s fault response with your protection and uptime strategy.
3) Transients are real, not theoretical.
High-density I/O, solenoid banks, contactor coils, and capacitive loads can generate fast load steps. Siemens specifies typical 2 ms settling for major load transitions, and an overshoot around 3% on power-up, giving you an engineering basis for stability planning rather than guessing.
Protection and overload behavior (what happens when things go wrong)
| Scenario | What the PSU can do (per datasheet) | Why it helps |
|---|---|---|
| Short-circuit during operation | Typical short-circuit current ~120 A for 25 ms | Supports downstream protective devices clearing quickly, improving selectivity |
| Short-circuit at start-up | Constant overload current typical ~46 A | Prevents uncontrolled current while still attempting to power loads |
| Long short-circuit event | Switchable: constant current characteristic (~46 A) or latching shutdown | Choose continuity vs hard shutdown behavior based on your cabinet philosophy |
| Overvoltage protection | Designed < 35 V | Adds a safety layer for 24 V electronics |
This is where Siemens supplies often feel “industrial” in the literal sense: they don’t just claim protection; they specify behaviors and indicators so technicians can diagnose quickly (green/yellow/red LEDs for normal, overload, latching shutdown).
Parallel operation and system scaling
For cabinets that need more than 40 A, Siemens indicates that two units can be connected in parallel for power increase, and the device includes a “bridging of equipment” function with switchable characteristic. Practically, parallel operation is relevant when you are powering large distributed I/O islands, multiple industrial switches, and extensive 24 V actuators from one cabinet zone, or when you want to split loads into zones while keeping the same PSU type.
In high-availability designs, a common pattern is redundancy rather than raw parallel power: two supplies feeding a redundancy module (often diode/MOSFET-based) so that one PSU can fail without collapsing the 24 V bus. While the datasheet here references accessories such as a buffer module and signaling module, redundancy strategy should be matched to your uptime requirements and downstream distribution architecture.
Installation guidance that reduces future pain
Input range selection is manual, not automatic.
This model is not wide-range input. You select 120 V or 230 V range via a wire jumper on the device, and the specified ranges differ (85–132 V vs 176–264 V). Getting that wrong is a classic commissioning mistake—especially in plants with mixed utility standards or transformer-fed panels.
Respect thermal spacing.
Siemens specifies natural convection operation up to 70 °C, but also gives required spacing (50 mm above and below). At 131 W typical dissipation under full load, airflow is not cosmetic. Leaving that clearance improves long-term reliability and reduces nuisance thermal derating.
Use appropriately sized conductors.
Output terminals support up to 10 mm², with two “+” and two “−” terminals. That is an explicit hint: at 40 A, you should distribute current across properly sized wiring and consider multiple feed points into distribution blocks to avoid single-point heating.
Product lifecycle and replacement path
Siemens explicitly labels 6EP1337-3BA00 as a phase-out product and points to successor 6EP3337-8SB00-0AY0. Additionally, Siemens communication about the SITOP modular line indicates the newer PSU8200 24 V/40 A platform replaced the older PSU100M 24 V/40 A (6EP1337-3BA00). For new projects, that matters: you can still source this part through channels like distributors, but BOM standardization usually benefits from aligning to the successor platform where possible.
Summary
Siemens 6EP1337-3BA00 (SITOP PSU100M) is a high-capacity 24 V DC DIN-rail power supply delivering 40 A (960 W) with adjustable output voltage, defined fast transient performance, selectable fault behavior (constant current vs latching shutdown), and cabinet-ready diagnostics. It’s aimed at serious 24 V distribution where stability, selectivity, and serviceability matter more than minimal cost. Because Siemens marks it as phase-out with a defined successor, it is best treated as a proven legacy choice for maintenance, retrofit, or continuity builds—while new designs should consider the recommended replacement family.
