SIEMENS 6ES5951-7LB12

Siemens SIMATIC S5 Power Supply 6ES5951-7LB12

Description

The Siemens 6ES5951-7LB12 is a power supply module for the obsolete but widely used SIMATIC S5-115U PLC series. It provides reliable and regulated DC power to the CPU and other modules within the S5 rack. This unit is essential for maintaining existing automation systems that rely on the S5 platform, offering a direct replacement for failed or aging units. With selectable input voltage and multiple DC outputs, it is a versatile component for S5-115U configurations.

Specifications

• Manufacturer: Siemens
• Product Series: SIMATIC S5
• Part Number: 6ES5951-7LB12
• Input Voltage: 115V / 230V AC (Selectable)
• Input Frequency: 47-63 Hz
• Output 1: +5V DC, 7A
• Output 2: +5.2V DC, 2.5A
• Output 3: +24V DC, 0.35A
• Total Current Capacity: 15A
• For use with: SIMATIC S5-115U systems

Application

This power supply is specifically designed for the main rack of a Siemens SIMATIC S5-115U programmable logic controller. It is commonly found in older manufacturing, process control, and automation applications that have not yet been upgraded to modern systems.

Country of Origin

This product is manufactured by Siemens in Germany.

CO2 Impact

Reusing this power supply module saves an estimated 60 kg of CO2 compared to producing a new one. This is equivalent to the emissions from driving a standard car for approximately 300 kilometers.

Availability

This is an obsolete item, available as a refurbished spare part. Stock is limited. Order now from spareparts2day for expert support and fast delivery.

FAQ

Question?

What is the purpose of the ‘Voltage Selector’ switch?

Answer?

The switch allows you to configure the module’s input voltage to match your local power grid, either 115V AC or 220/230V AC. Incorrectly setting this can damage the unit.

Question?

Is this power supply compatible with other SIMATIC S5 racks, like the S5-100U or S5-135U?

Answer?

No, the 6ES5951-7LB12 is specifically designed for the SIMATIC S5-115U PLC system rack. Using it with other S5 families is not recommended as the power ratings and backplane connectors may differ.

Question?

What does the ‘BATT LOW’ indicator mean, and what type of battery is required?

Answer?

The ‘BATT LOW’ LED indicates that the external backup battery, used for retaining the PLC program in RAM during a power outage, is depleted. It requires a 3.4V to 3.6V lithium battery, which connects to the ‘EXT BATT’ terminals.

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Last Update: Friday, March 13, 2026