Siemens 6ES5955-3NF42 Power Supply Unit

Engineered for SIMATIC S5 Backplane Power

This unit supplies stable DC power to the entire S5 rack. It provides reliable energy for the Siemens 6ES5955-3NF42 system. You will find this power supply in all SIMATIC S5 controller cabinets. Unlike basic PSUs, this version includes overload and short-circuit protection. It delivers up to 10 Amps at 24V DC for multiple modules.

Technical Specifications & Physical Dimensions

We designed this power supply for continuous industrial operation. The table below presents all verified technical specifications.

Parameter	Specification
Physical Dimensions (W x H x D)	250mm x 125mm x 130mm
Total Weight	2.8 kg (2800 grams)
Input Voltage Range	120V AC or 230V AC (selectable)
Input Frequency	50/60 Hz ±5%
Output Voltage	24V DC nominal (22.8V – 25.2V)
Output Current Rating	10 Amps continuous
Output Power	240 Watts maximum

Functional Architecture and Protection Features

This power supply connects to the S5 backplane via a dedicated connector. It uses a switching mode design for high efficiency. You can select 120V or 230V input using a slide switch. Moreover, the unit includes electronic current limiting on the output. This component prevents damage during overload conditions. Consequently, the PSU automatically recovers when the fault clears.

Installation and Operational Guidelines

The Siemens 6ES5955-3NF42 achieves 88% efficiency at full load. It requires 50mm clearance above and below for airflow. You must set the voltage selector before applying power. Always use a circuit breaker rated for 16 Amps on the input side. This practice protects the internal input fuses from damage. Furthermore, the unit includes a green LED for output status indication. This feature provides immediate visual confirmation of proper operation.

Physical Characteristics and Environmental Limits

This power supply has a rugged, ventilated metal housing. Its substantial 2.8 kg weight reflects the heavy-duty transformer design. The layout follows Siemens standard S5 rack specifications. Therefore, it fits securely into the leftmost slot of any S5 rack. The unit requires no additional mounting hardware for installation. In addition, it maintains stable operation between 0°C and 55°C ambient temperature. You can store this PSU safely between -25°C and 85°C.