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The Siemens 6ES5 951-7LD21 (PS 951) is a robust power supply module engineered for the legacy SIMATIC S5-115U and S5-115H PLC systems. This unit converts 120-230 VAC input power into a stabilized 5 VDC output, supplying either 7 A or 15 A to the backplane bus to support central processing units and I/O modules. It is designed to maintain system stability in demanding industrial environments, such as automotive manufacturing, power generation, and metal processing, by protecting sensitive logic circuits from AC line fluctuations and voltage instability.
This power supply module is a critical component for maintaining uptime in legacy Siemens S5-115 series PLC installations. It is typically deployed in large-scale automation systems where consistent DC power is required for CPU operation and extensive I/O configurations.
| Model | 6ES5 951-7LD21 |
| Brand | Siemens |
| System Series | SIMATIC S5-115U / S5-115H |
| Module Type | Power Supply Module (PS 951) |
| Input Voltage | 120 VAC to 230 VAC |
| Output Voltage | 5 VDC |
| Output Current | 7 A / 15 A |
| Operating Temperature | 0 to 60 deg C |
| Status | Discontinued |
No, the 6ES5 951-7LD21 is specifically designed for the mechanical and electrical requirements of the S5-115U and S5-115H series. It is not intended for use in the larger S5-135U or S5-155U rack architectures.
No, this specific version does not include an integrated backup battery. It relies on internal capacitors for short-term ride-through capability during minor power interruptions.