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The Siemens 6ES5955-3NC42 provides stable DC power to your S5-155U rack. This power supply module converts AC line voltage into regulated 24V DC. It feeds all backplane modules and connected field devices.
Technical specifications of Siemens 6ES5955-3NC42
| Parameter | Specification |
|---|---|
| Brand | Siemens |
| Model | Siemens 6ES5955-3NC42 |
| Product Family | SIMATIC S5 |
| Sub-Family | S5-155U |
| Category | Power Supply Module (PS 955) |
| Input Voltage | 120/230V AC (selectable) |
| Input Frequency | 47 to 63 Hz |
| Output Voltage | 24V DC regulated |
| Output Current | 15 Amps continuous |
| Output Power | 360 Watts maximum |
| Efficiency | Approximately 85% |
| Ripple | ≤ 50 mV peak-to-peak |
| Hold-up Time | 20 ms at full load |
| Internal Components | 1 transformer, 1 rectifier, 3 capacitors, 1 fan |
| Energy Storage | 3 x electrolytic capacitors (3300 µF each) |
| Cooling Method | Internal fan with front grille |
| Dimensions (L x W x H) | Approx. 35 cm x 15 cm x 10 cm |
| Weight | Approx. 2.8 kg |
| Operating Temperature | 0°C to 60°C |
Detailed Technical Analysis
The Siemens 6ES5955-3NC42 accepts either 120V or 230V AC input. You select the correct voltage using a switch on the side panel. The module then converts this AC power into stable 24V DC output. It delivers up to 15 amps for powering your entire rack.
Now let us examine its energy storage capabilities. The Siemens 6ES5955-3NC42 contains three large electrolytic capacitors. Each capacitor stores 3300 microfarads of electrical charge. Together they provide 20 milliseconds of hold-up time at full load. This feature bridges short power interruptions without resetting your PLC.
The module includes an internal cooling fan for thermal management. You will see the fan grille on the front panel. The Siemens 6ES5955-3NC42 achieves approximately 85% efficiency. It produces less than 50 millivolts of ripple at the output terminals. This clean power ensures stable operation of sensitive analog modules.
Installation and Wiring Guidelines
You mount the Siemens 6ES5955-3NC42 into the designated power supply slot. This position is typically on the far left of an S5-155U rack. Connect the AC input wires to the terminal block at the bottom. Use appropriate wire gauges for 15-amp current capacity.
The Siemens 6ES5955-3NC42 automatically distributes 24V DC to the backplane. You do not need any separate wiring to other modules. The internal fan requires adequate clearance for air intake. Leave at least 5 centimeters of space in front of the grille.
Practical Applications
Engineers use this power supply for large S5-155U systems. For example, a fully populated rack with 20 modules needs this 15A capacity. The Siemens 6ES5955-3NC42 also powers external sensors through the I/O modules. Its high hold-up time prevents nuisance shutdowns from grid fluctuations.
Summary
To conclude, the Siemens 6ES5955-3NC42 delivers 15 amps of regulated 24V DC power. It weighs 2.8 kilograms and includes three storage capacitors. Choose this power supply for reliable operation of your S5-155U system.