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Compact Energy Source for SIMATIC S5-95U Systems
The Siemens 6ES5951-7NB21 power supply unit provides regulated DC power to S5-95U programmable controllers and connected expansion modules. This compact unit converts 24V DC input to stable 5V DC output for logic circuits and backplane bus operation. It supports the CPU and up to 32 I/O modules, making it suitable for small to medium-scale applications.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Siemens |
| Model | 6ES5951-7NB21 |
| Series | SIMATIC S5-95U |
| Product Type | Power Supply Unit |
| Input Voltage | 24V DC |
| Input Voltage Range | 20.4V to 28.8V DC |
| Output Voltage | 5V DC |
| Output Current | 3A |
| Output Power | 15W |
| Efficiency | Approx. 80% |
| Voltage Tolerance | ±2% |
| Residual Ripple | < 20 mVpp |
| Protection Features | Short-circuit and overload protection |
| Operating Temperature | 0°C to 60°C |
| Weight | 0.35 kg |
| Dimensions (W x H x D) | 25 x 120 x 116.4 mm |
| Protection Rating | IP20 |
Stable Logic Power Delivery
The Siemens 6ES5951-7NB21 converts 24V DC field power into clean 5V DC for processor and backplane bus logic. This conversion ensures stable operation for CPU, I/O, and communication modules across the rack. Moreover, the unit’s 3A capacity supports the typical current draw of a fully populated system.
Protection and Reliability
This power supply incorporates short-circuit protection to prevent damage from wiring faults or module failures. The overload protection also maintains output stability during temporary current spikes. These safety features ensure continuous system operation and protect sensitive electronics.
Integration and Installation
The unit mounts directly onto the S5-95U base unit, eliminating separate mounting requirements. It fits within the standard 25mm single-width footprint, preserving rack space for other modules. The lightweight 0.35 kg design also simplifies handling and installation procedures.
Operating Environment
The module operates reliably across a temperature range of 0°C to 60°C for industrial automation settings. It suits applications in machinery, assembly lines, and process control systems. The IP20 rating also ensures safe indoor operation where protection against solid objects exceeding 12mm is sufficient.