40A Power Supply for SIMATIC S5 Controllers
The Siemens 6ES5955-3LF12 power supply unit delivers reliable power to SIMATIC S5-135U, S5-150U, and S5-155U central controllers, as well as EU 185U expansion units . This high-capacity unit provides stable DC power for demanding industrial automation systems. It incorporates comprehensive monitoring and protection features for system reliability.
Technical Specifications
| Parameter | Specification |
|---|---|
| Model Number | 6ES5955-3LF12 |
| Brand | Siemens |
| Category | Power Supply Unit |
| Product Line | SIMATIC S5 955 |
| Input Voltage | 115/230 V AC (selectable) |
| Input Frequency | 48 to 63 Hz |
| Rated Output Voltage 1 | 5.1 V DC ±0.5% |
| Rated Output Current 1 | 40 A DC |
| Rated Output Voltage 2 | 24 V DC (+25%/-17%) |
| Rated Output Current 2 | 2.8 A DC |
| Rated Output Voltage 3 | 15 V DC ±5% (with supplementary module) |
| Rated Output Current 3 | 2 A DC |
| Rated Output Voltage 4 | 24 V DC (+6V/-5V) front terminals |
| Rated Output Current 4 | 0.4 A DC |
| Efficiency | Typical ≥70% with fan |
| Power Factor | 0.73 |
| Inrush Current (230V) | 200 A (peak) |
| Dimensions (HxWxD) | Approx. 180 x 120 x 90 mm |
| Weight | Approx. 5.3 kg |
| Mounting | Rack-mountable |
| Country of Origin | Austria |
Multi-Output Power Architecture
This power supply generates multiple DC outputs for different system requirements. The primary 5.1 V output delivers 40 A for the central controller logic. Two additional outputs provide 24 V and 15 V for peripheral modules. Moreover, front terminals supply 24 V at 0.4 A for convenient field connections .
Comprehensive Protection Features
Overvoltage protection shuts down the 5.1 V output when it exceeds 6 V ±5% . Current limiting activates during overload conditions at 1.05 to 1.15 times the rated current. The input fuse provides primary-side protection with a 6.3 A fast-blow fuse. Consequently, this unit protects both itself and connected modules effectively.
Integrated Cooling and Monitoring
Two axial fans provide active cooling for high-load operation . Fan monitoring detects any stoppage and signals the condition via LED and relay contacts. The system can optionally shut down output voltages 6 to 10 seconds after fan failure. This thermal management ensures reliable operation in demanding industrial environments.
Battery Backup Support
The unit supports external battery connection for data retention during power outages. The battery backup maintains memory contents in the central controller. This feature proves essential for critical automation processes that require continuous data integrity.
Application Suitability
This power supply serves S5-135U, S5-150U, and S5-155U central controllers. It also supports EU 185U expansion units in distributed automation systems. The unit delivers consistent power for large, high-demand configurations. Its proven reliability makes it a trusted component in legacy SIMATIC S5 installations.
Details
| Weight | 5.3 kg |
|---|---|
| Dimensions | 180 × 120 × 90 mm |
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