Siemens 6EP1333-2BA20 — SITOP PSU100S 5A Selection Guide

By Abdullah Zahid
13 min read
Siemens 6EP1333-2BA20 SITOP PSU100S 24V 5A compact DIN rail power supply for industrial control cabinet

Siemens 6EP1333-2BA20 SITOP PSU100S 24 V / 5.0 A Stabilized Power Supply: Specifications, Alternatives and Selection Guide

When a controls engineer or panel builder searches for the Siemens 6EP1333-2BA20 by catalog number, the purchase decision is almost always already in motion. The question is not whether to use a SITOP PSU100S — it is whether the 5A variant is the right capacity, whether the input voltage range covers the site supply, and whether lead time supports the build schedule. This article answers all three and gives you the technical context to confirm or redirect your order before the PO is cut. The 6EP1333-2BA20 is a compact switched-mode DC power supply delivering 24V DC at 5A continuous output, with a 50mm DIN rail form factor, galvanic SELV isolation, and a 150% power boost function for transient inrush loads.

If you have already confirmed this is the right part, check current pricing and availability at LeadTime.ca — ships worldwide.

Who Should Buy the 6EP1333-2BA20 — and Who Shouldn't

The Siemens 6EP1333-2BA20 is the right choice for engineers building or maintaining a 24V DC control rail where continuous load falls between 3A and 5A and cabinet space is at a premium.

  • Your total connected load (PLC modules, solenoids, sensors, relays) does not exceed 5A continuous under normal ambient conditions
  • Your site AC supply is single-phase 120V or 230V (the PSU auto-ranges 85–132V and 170–264V)
  • Your enclosure uses 35mm DIN rail and can accommodate a 50mm wide module
  • You need SELV galvanic isolation for safety circuits or ATEX-rated installations in classified hazardous areas
  • You have transient inrush loads such as solenoid banks that benefit from the 7.5A boost for 5 seconds once per minute
  • Your system operates within -10 to +70°C ambient (with derating applied above +60°C at 3% per Kelvin)

If your confirmed continuous load is under 2.5A, the 6EP1332-2BA20 is the correct selection — smaller footprint, lower cost. If load exceeds 6A or future expansion is planned, step up to the 6EP1334-2BA20 (10A). Neither redundant nor hot-swap architectures are native to this single-unit PSU; an N+1 design requires a different product family.

On this page:

What the 6EP1333-2BA20 Actually Does in a Control System

The Siemens 6EP1333-2BA20 is a single-phase AC-to-DC switched-mode power supply that converts 120V or 230V AC from the panel supply into a regulated 24V DC rail for control logic, field devices, and safety circuits. It is not a general-purpose bench supply — it is a DIN rail module that lives inside an industrial enclosure and powers everything downstream of the main disconnect that operates on 24V: PLC digital I/O modules, transmitters, solenoid valve coils, safety relay coils, proximity sensors, and signal conditioning loops.

The output is adjustable from 22.8V to 28V via a panel-accessible potentiometer, which allows commissioning engineers to fine-tune rail voltage under load rather than accepting a fixed nominal. Galvanic isolation (SELV rated) is built in — this is not optional and is not an add-on module. The power boost function, which delivers 7.5A for 5 seconds once per minute, addresses one of the most common undersizing errors: solenoid pull-in inrush. A solenoid drawing 1A holding current may draw 2–3A during energization, and this PSU absorbs that transient without tripping or collapsing the 24V rail. The 5A continuous rating and 50mm physical width make the 6EP1333-2BA20 the mid-capacity workhorse of the SITOP PSU100S family, accounting for approximately 60% of the series install base across manufacturing and process automation installations worldwide.

Where the 6EP1333-2BA20 Sits in a Typical Control Cabinet

This PSU sits between the AC branch circuit — protected by a 6A Characteristic C circuit breaker — and the 24V DC control bus that feeds all downstream devices in the enclosure. It is the voltage translation and isolation boundary in the signal chain.

  • Upstream: Single-phase AC supply (120V or 230V) from main panel, through a 6A Characteristic C circuit breaker feeding the PSU input terminals (L, N, PE)
  • The 6EP1333-2BA20 performs AC-to-DC conversion with galvanic SELV isolation, clamping output to a regulated 24V DC rail (adjustable 22.8–28V)
  • Downstream on the 24V bus: PLC CPU and I/O modules, safety relay modules, solenoid valve coil drivers, and 2-wire and 3-wire sensors
  • Transient inrush loads such as solenoid banks or magnetic clutch coils are managed by the 7.5A boost function without additional buffering hardware
  • Status monitoring: The on-board LED indicator confirms 24V output is live; no external monitoring relay is included in this base model

Which Industries and Machine Types Use This PSU

The 6EP1333-2BA20 is the standard replacement and new-build choice for 24V rail power in discrete manufacturing control cabinets. Panel builders specifying cabinets for automotive assembly lines, packaging machinery, and conveyor systems reach for the 5A SITOP as the default mid-capacity PSU because it handles a mixed load of 4–6 I/O modules, 2–3 solenoids, and a bank of proximity sensors without margin anxiety.

In process automation — bottling, chemical dosing, water treatment — this PSU powers the 24V logic rail for PLC-based PID control loops, where SELV isolation is a compliance requirement, not a preference. The same isolation rating makes it directly applicable to safety relay circuits in machinery governed by IEC 61508 functional safety standards.

For installations in classified hazardous areas — petrochemical, grain handling, paint booths — the ATEX approval on the 6EP1333-2BA20 removes the need for a separate intrinsically safe barrier supply for the 24V logic rail, provided the PSU itself is housed in an enclosure with IP54 or better protection rating.

Maintenance teams in food and beverage or pharmaceutical plants also specify this model for emergency PSU swaps: the 50mm width and standard SITOP terminal layout mean a like-for-like replacement takes under 20 minutes without rewiring the output bus.

Application Typical Deployment
PLC control cabinet (discrete manufacturing) Main 24V DC rail powering CPU, digital I/O, and 2–3 solenoid coil drivers
Process automation (bottling / chemical) Isolated 24V supply for PID loop logic and transmitter power on DIN rail
Safety relay circuits (IEC 61508 applications) SELV-isolated 24V coil power for safety relays and emergency-stop logic chains
Hazardous area (ATEX Zone 2 / UL Class 1 Div 2) 24V logic power inside IP54+ enclosure in classified atmosphere without separate barrier supply
Machine replacement / emergency swap Direct like-for-like swap in existing SITOP PSU100S-based enclosure (same 50mm footprint)
Conveyor and logistics automation 24V sensor and solenoid bus for accumulation conveyor zone controls

6EP1333-2BA20 Key Specifications: What Matters at Purchase Time

Specification Value
Rated Input Voltage 1-phase AC 120/230V, 50–60 Hz (auto-ranging 85–132V / 170–264V)
Rated Output Voltage 24V DC nominal (adjustable 22.8–28V)
Rated Output Current 5A continuous
Peak Output Current 6A at 120% rating (-10 to +45°C)
Power Boost 7.5A for 5 seconds, once per minute (150%)
Output Isolation Galvanic SELV (Safety Extra Low Voltage)
Short-Circuit Protection Built-in, output short-circuit proof
Dimensions (W × H × D) 50 × 125 × 125 mm
Operating Temperature -10 to +70°C (derating 3% per Kelvin above +60°C)
Agency Approvals ATEX (Ex), UL Class 1 Division 2, EN 60079-0, EN 60079-15

Full technical specifications are available on the product page at LeadTime.ca.

6EP1333-2BA20 vs 6EP1332 and 6EP1334: Choosing the Right Capacity

The SITOP PSU100S family spans three current ratings. All three share the same 24V DC output, SELV isolation, and power boost architecture. The selection comes down entirely to load calculations and physical width.

Model Rated Current Boost (150% × 5s) Width Best For
6EP1332-2BA20 2.5A 3.75A 32.5mm Light loads, space-constrained cabinets, cost-sensitive applications
6EP1333-2BA20 5.0A 7.5A 50mm Standard mid-capacity (THIS MODEL) — mixed I/O, sensors, 2–3 solenoids
6EP1334-2BA20 10.0A 15A 70mm High-load applications, future growth headroom, multiple solenoid banks

The 2.5A variant (6EP1332-2BA20) is typically 15–25% less expensive; the 10A variant (6EP1334-2BA20) is typically 25–40% more expensive than this 5A model. If your load calculation lands between 4.5A and 6A continuous, choose the 10A variant — do not rely on the boost function as a permanent operating margin. If the 6EP1333-2BA20 matches your load profile, check current stock and pricing at LeadTime.ca.

Expert Verdict: Honest Assessment for Engineers and Buyers

The Siemens 6EP1333-2BA20 earns its position as the default 24V PSU in new panel builds and replacement orders for one straightforward reason: it solves the most common control cabinet power problem — mixed loads with transient peaks — without requiring external buffering hardware or oversizing to a 10A supply. The 7.5A boost function is a genuine engineering advantage for solenoid-heavy applications, not a marketing figure. The SELV isolation and ATEX approval mean a single SKU covers standard industrial and hazardous area requirements without additional certification paperwork. With over 500,000 SITOP PSU100S units installed across manufacturing automation since 2012 and a field replacement rate under 2% per annum, the reliability profile is not theoretical.

The honest limits: this is not a redundant architecture. If your system cannot tolerate a PSU failure without immediate process interruption, a single 6EP1333-2BA20 is not sufficient — you need N+1 design using a different product family. The on-board LED provides binary status (output live or not); it does not offer remote monitoring, current measurement output, or IO-Link diagnostics available on higher-tier SITOP variants. If ambient consistently exceeds +60°C, the 3% per Kelvin derating is real and measurable — a cabinet running at +65°C should budget the continuous load at roughly 3.5A, not 5A. And if your total load sits above 6A with no reduction path, the 6EP1334-2BA20 is the correct part regardless of physical preference.

From a procurement standpoint, the 6EP1333-2BA20 is a standard stock item. Lead times of 3–5 working days through established distributors are typical, and the SITOP PSU100S family has a minimum 7-year replacement availability horizon from current distribution. Volume pricing is available for panel builder and OEM quantities — the per-unit cost at 10-unit quantities can meaningfully reduce cabinet BOM cost relative to single-unit orders. If this matches your system requirements, view current stock and pricing at LeadTime.ca.

For volume pricing or to confirm lead time before committing to a build, contact the LeadTime.ca team directly — we ship worldwide.

Installation and Wiring Overview for the 6EP1333-2BA20

The following is an installation overview. Engineers requiring full wiring diagrams and step-by-step commissioning procedures should refer to the Siemens SITOP PSU100S operating instructions and applicable IEC 60364-3 / EN 50178 wiring standards.

  • Verify AC input supply is de-energized and confirmed dead with a multimeter before connecting terminals; wire input leads (L, N, PE) to the AC input terminals using copper cable rated minimum 65/75°C
  • Connect 24V DC output leads observing polarity — red to +24V, black or brown to GND — and confirm the upstream 6A Characteristic C circuit breaker is in place before energizing
  • On first power-up, adjust the output potentiometer with a small-slot screwdriver to desired voltage within the 22.8–28V range under no-load conditions, then verify with a multimeter; confirm LED status indicator illuminates before connecting downstream loads
  • In ATEX-classified atmospheres, do not adjust the voltage potentiometer while explosive atmosphere is present; ensure the PSU is housed in an enclosure providing IP54 or better protection per the ATEX installation requirements
  • Maintain clear convection paths above and below the PSU (minimum clearance as marked on the unit); do not pack adjacent modules tight against the convection openings, particularly in cabinets where ambient may approach +60°C

Compatible System Components and Expansion Considerations

The 6EP1333-2BA20 operates as a standalone supply on a standard 35mm DIN rail and is compatible with the broader SITOP ecosystem for load distribution and monitoring. The following components are relevant when building or expanding a system around this PSU.

  • 6EP1332-2BA20 — 2.5A SITOP PSU100S variant for secondary or auxiliary 24V rails in the same enclosure where load splitting is preferable to a single higher-capacity supply
  • 6EP1334-2BA20 — 10A SITOP PSU100S variant when total load at the design phase already approaches the 5A continuous ceiling of this model
  • SITOP selective current limiting modules — downstream current distribution protection, allow individual branch circuit protection on the 24V bus without additional fusing hardware
  • SITOP buffer modules — adds ride-through capacitance to the 24V bus for brief AC input interruptions, complementing the 6EP1333-2BA20 in applications with intermittent supply quality
  • 6A Characteristic C miniature circuit breaker (MCB) — required upstream protective device per the PSU input specification; must be same voltage rating as site AC supply

Wrong-Part Prevention: Six Checks Before You Order

Run through this checklist before submitting any order for the 6EP1333-2BA20 — these are the six most common points of specification mismatch that result in returns, rework, or field failures.

  1. Confirm input voltage: Is your site 120V or 230V single-phase AC? (This PSU auto-ranges 85–132V or 170–264V but verify)
  2. Verify continuous current draw: Add all connected loads (solenoids, transmitters, PLC modules, lighting). Does total not exceed 5A? (6A at cold temp, 3A under 150% boost)
  3. Check output voltage window: Does your system accept 22.8 to 28V DC? (This PSU is adjustable within this range only)
  4. Confirm DIN rail mounting: Is your enclosure equipped with DIN rail? (This PSU requires 35mm DIN rail)
  5. Verify isolation requirement: Do you need SELV (Safety Extra Low Voltage) galvanic isolation? (This PSU provides it; required for safety circuits)
  6. Check operating temperature: Will ambient stay in -10 to +70°C range? (Derating applies above +60°C; operation outside range voids spec)

If any item on this checklist raises a question about fit, contact the LeadTime.ca team before ordering — or review the full specification on the product page to confirm.

Frequently Asked Questions

Does the 6EP1333-2BA20 work on both 120V and 230V AC input without a switch?

Yes. The input is auto-ranging across 85–132V AC and 170–264V AC, 50–60 Hz. No manual voltage selection switch is required. Verify your actual site voltage falls within one of these two windows using a multimeter before installation — nominal 120V or 230V sites are both covered, but verify under-voltage conditions at the panel are not pulling the supply below 85V.

How do I calculate whether 5A is enough for my cabinet?

List every device drawing from the 24V rail and record its rated current in amperes. Sum the continuous holding currents, then separately estimate peak inrush — solenoid coils typically draw 2–3 times holding current during energization. If continuous sum stays under 5A and peak transients stay under 7.5A in duration under 5 seconds, the 6EP1333-2BA20 is sized correctly. If your continuous draw exceeds 4.5A, add the 6EP1334-2BA20 (10A) to your evaluation — the boost function is not intended to cover continuous overload.

What does the power boost function actually do and when does it reset?

The boost function allows the PSU to deliver 7.5A — 150% of rated output — for up to 5 seconds. After boost activation, the function resets once per minute, meaning if solenoids are cycling continuously at intervals shorter than 60 seconds, each energization cycle may not have a fully reset boost available. For applications with high-frequency solenoid cycling, calculate whether the continuous 5A rating alone can handle the load without relying on boost.

Is the 6EP1333-2BA20 suitable for use in hazardous (explosive) areas?

Yes, the 6EP1333-2BA20 carries ATEX approval (Ex) and UL Class 1 Division 2 certification, compliant with EN 60079-0 and EN 60079-15. However, it must be installed inside an enclosure rated IP54 or better for hazardous area use. Do not adjust the output voltage potentiometer while an explosive atmosphere is present.

How quickly can a failed unit be replaced and is the SITOP PSU100S still actively manufactured?

The SITOP PSU100S family remains an active product line with a minimum 7-year replacement availability horizon from current distribution. Standard stock lead times through established industrial distributors including LeadTime.ca are typically 3–5 working days. The 50mm DIN rail footprint and standard SITOP terminal layout allow a like-for-like swap in an existing enclosure without output bus rewiring.

What circuit breaker is required upstream of the 6EP1333-2BA20?

Siemens specifies a 6A circuit breaker with Characteristic C tripping curve as the recommended upstream protective device. Characteristic C is appropriate because switched-mode PSUs have inrush current on startup that a Characteristic B breaker might trip on. The breaker must be rated for the same voltage as your AC supply (120V or 230V) and installed per your applicable electrical code — NEC, CEC, or equivalent.

Why Source the 6EP1333-2BA20 Through LeadTime.ca

  • Ships worldwide — not limited to any single country or region; orders fulfilled from North American inventory with international logistics support
  • Specializes in industrial automation hardware including hard-to-source SITOP variants and current-production Siemens catalog items
  • Volume pricing available for OEM, panel builder, and multi-unit procurement quantities — contact for a quote before finalizing BOM cost
  • Response times suited to both emergency replacement orders and planned procurement cycles
  • Full product page with technical documentation links: Siemens 6EP1333-2BA20 at LeadTime.ca
  • Direct contact for lead time confirmation, volume quotes, and technical questions: LeadTime.ca contact page

At-a-Glance Summary

  • Catalog number: 6EP1333-2BA20 — SITOP PSU100S 24 V / 5.0 A Stabilized Power Supply
  • Output: 24V DC nominal, adjustable 22.8–28V, 5A continuous, 6A at 120% in -10 to +45°C
  • Power boost: 7.5A for 5 seconds once per minute (150% of rated output) for solenoid and inrush transients
  • Input: Auto-ranging 85–132V / 170–264V AC, single-phase, 50–60 Hz
  • Physical: 50mm wide, 125 × 125mm (H × D), 0.4 kg, 35mm DIN rail mount
  • Isolation: Galvanic SELV — suitable for safety circuits per EN 61131-2 and IEC 61508
  • Approvals: ATEX (Ex), UL Class 1 Division 2, EN 60079-0, EN 60079-15
  • Operating temperature: -10 to +70°C; derating applies at 3% per Kelvin above +60°C
  • Recommended upstream breaker: 6A Characteristic C
  • Family context: Mid-capacity between 6EP1332-2BA20 (2.5A / 32.5mm) and 6EP1334-2BA20 (10A / 70mm)
  • Typical lead time: 3–5 working days from stock through LeadTime.ca, ships worldwide