6ES7307-1EA00-0AA0 SIEMESN 6ES73O7-1EAOO-OAAO 6ES73071EA000AA0 POWER SUPPLY

Siemens 6ES7307-1EA00-0AA0 | SIMATIC S7-300 PS 307 Power Supply — 5A / 24VDC / 120W / 120/230VAC Auto / 87% Efficiency / 5ms Bridging

Every S7-300 Station Starts Here

The PS 307 is the electrical foundation of every standard SIMATIC S7-300 system. No CPU, no signal module, no communication processor operates until the PS 307 converts the facility's AC mains supply into the 24V DC that runs the backplane bus and powers the installed modules. It is not an option — it is the station's starting point.

A single PS 307 output rail serves both purposes simultaneously: it supplies the S7-300 system voltage to all installed modules through the rail bus connector and delivers 24V DC to field devices — proximity sensors, solenoid valve coils, contactor control circuits, indicator lamps — through the output terminals. No separate field power supply is needed provided the total current draw stays within the 5A limit.

The automatic voltage range switching eliminates a commissioning risk that exists with fixed-range supplies. The PS 307 detects the input voltage and adjusts its internal circuitry accordingly — the same module connects to 120VAC in North America, 230VAC in Europe, or any mains voltage within the permitted range, without a jumper, a selector switch, or a risk of applying the wrong voltage to a fixed-range supply.

Key Specifications

18W Power Loss — The Cabinet Thermal Budget

The 18W dissipated by the PS 307 as heat is a real number that must appear in every cabinet thermal calculation. Combined with the CPU (4–6W), signal modules (40–80mW each), and any function or communication modules in the rack, a mid-size S7-300 installation contributes 30–50W total to the cabinet's heat load. If natural convection cannot clear this fast enough, internal temperatures rise above module ratings and premature failures follow.

The 87% switching-mode efficiency is what keeps this heat contribution manageable. A linear supply delivering the same 120W would typically run at 50–60% efficiency, dissipating 40–60W — nearly three times the thermal load in the same panel space. The switch-mode design is not just a cost feature; it is a thermal management advantage in any densely built cabinet.

Parallel Operation — Extending to 10A

Two PS 307 5A modules can be wired in parallel on the same 24V rail to deliver a combined 10A when the station's power budget exceeds one module's capacity. Both modules share the load current. If one fails, the other continues at 5A — potentially enough to keep critical system functions running.

This is not a true hot-standby redundant supply (no output diodes or active load sharing, so a brief voltage perturbation occurs on failover). For applications where any 24V supply interruption is unacceptable, a dedicated redundant power supply module with load-sharing and hot-swap circuitry should be specified instead.

Inrush and MCB Selection

The 20A inrush at power-on — with I²t of 1.2 A²s — determines the required upstream circuit protection. Type B miniature circuit breakers (trip at 3–5× rated current instantaneously) will nuisance-trip when the PS 307 is energised. Siemens recommends a minimum 6A Type C MCB — Type C tolerates 10–15× rated current instantaneously before tripping, which is appropriate for the PS 307's inrush profile. For two parallel PS 307 modules, size the MCB for the combined inrush.

FAQ

Q1: Can the PS 307 supply both the S7-300 system voltage and field devices from one output rail?

Yes — this is the intended use. The backplane bus draws system voltage through the rail connector; field-wired loads draw from the output terminals. Calculate the current budget: add all S7-300 module 24V current draws from their datasheets plus field device currents (sensors, solenoids, lamps). Total must stay below 5A continuously. If the budget approaches 5A, add a second PS 307 for the field load rail or run both in parallel.

Q2: What upstream circuit protection does the PS 307 require?

A minimum 6A Type C MCB per PS 307. Type C breakers tolerate the 20A inrush at energisation without nuisance tripping. Type B breakers will trip on the inrush. The I²t of 1.2 A²s characterises the inrush energy — use this value to verify the MCB's I²t let-through rating when selecting protection for multiple PS 307 units or parallel configurations.

Q3: Is the EA01-0AA0 successor directly interchangeable?

Yes — a direct drop-in replacement. The 6ES7307-1EA01-0AA0 has identical physical dimensions, mounting geometry, output specification (24VDC, 5A), input specification (auto 120/230VAC), and connector placement as the EA00-0AA0. Internal component updates improve reliability; no user-visible specification changed. Install the successor without any cabinet modification or wiring change.

Q4: What is the 5ms bridging time and when is it useful?

The PS 307 continues delivering 24V DC output for at least 5ms after AC input fails, using energy stored in its internal filter capacitors. This covers brief supply dips from large motor starts, automatic transfer switching, and transient distribution disturbances — events common in industrial power distribution. It is not sufficient for extended outages; those require a UPS on the AC input. The 5ms is not adjustable.

Q5: Must the PS 307's 0V output be grounded?

Yes. Connect the 0V terminal to the cabinet's PE (protective earth) bus. An ungrounded (floating) 24V DC rail creates common-mode voltage conditions that cause measurement drift in analogue I/O modules and interference in RS-485 and PROFIBUS communication circuits. The PS 307 datasheet specifies the exact grounding connection and recommended wiring practice.