Siemens 6ES5955-3LC12 Power Supply

Technical Specifications and Power Ratings

This power supply module provides regulated DC power for Siemens SIMATIC S5-155U PLC systems. The Siemens 6ES5955-3LC12 converts incoming AC voltage into stable outputs for backplane operation. You can mount this unit in the dedicated power supply slot of the main rack. Its robust design supports fully populated chassis configurations reliably. The module weighs approximately 3.2 kilograms. Its dimensions measure 30 cm in height, 25 cm in width, and 22 cm in depth.

Parameter	Specification
Brand	Siemens
Model	6ES5955-3LC12
Category	Power Supply Module / Rack Power Unit
Weight	3.2 kg
Height	30 cm
Width	25 cm
Depth	22 cm
Input Voltage	115/230V AC (selectable via jumper)
Input Frequency	47 to 63 Hz
Input Current	4.5 Amps at 115V AC / 2.2 Amps at 230V AC
Output +5V DC	120 Watts (24 Amps)
Output +15V DC	30 Watts (2 Amps)
Output -15V DC	15 Watts (1 Amp)
Output +24V DC	48 Watts (2 Amps)
Total Output Power	213 Watts
Hold-up Time	30 milliseconds at full load
Efficiency	85% typical
Energy Storage	Built-in DC bus electrolytic capacitors
Component Count	Transformer, switching regulator, filter capacitors, cooling fan

Output Distribution and Protection Features

The module generates four distinct DC outputs for different system components. The +5V supply powers all logic circuits and CPU modules primarily. The +15V and -15V supplies drive analog I/O circuitry exclusively. The +24V supply operates relays, solenoids, and field devices. Each output includes independent short-circuit and overvoltage protection circuits. The Siemens 6ES5955-3LC12 will shut down safely during overload conditions. Recovery requires a manual power reset after removing the fault completely.

Energy Storage and Ride-Through Capability

The built-in DC bus capacitors store energy for brief power interruptions. These capacitors provide 30 milliseconds of hold-up time at full rated load. Consequently, the PLC continues operating through momentary voltage sags or brownouts. The module contains no replaceable battery for long-term energy storage. An internal cooling fan maintains safe operating temperatures continuously. The fan activates as soon as the module receives input power. You should keep the fan intake vents clear of dust and debris.

Installation and Operational Guidelines

You must mount this module in the leftmost position of the S5-155U base rack. The module connects to the backplane through a dedicated high-current power bus. You must select the correct input voltage using the internal jumper before power-up. Operating the module on the wrong voltage will cause immediate damage. The unit operates efficiently across a wide ambient temperature range of 0°C to 50°C. Proper ventilation around the module ensures maximum thermal performance and longevity.