The Siemens 6ES5951-7ND21 is a dedicated power supply module engineered for the Simatic S5-115U/H programmable logic controller (PLC) series. This unit serves as a critical component in legacy automation systems, converting an input voltage range of 19.2 to 30 VDC into a regulated 5 VDC output. Designed for high-availability industrial environments, it ensures stable power delivery to backplane components, effectively reducing the risk of system resets and unplanned downtime in critical control applications.
Features
Designed specifically for the Simatic S5-115U/H rack-based architecture.
Flexible output capacity: Delivers 7 A at 5 VDC as a standalone unit, or up to 15 A at 5 VDC when paired with a compatible fan subassembly.
Optimized for high-density cabinet mounting within standard S5 rail configurations.
Supports optional external battery integration for memory retention within the S5-115 rack environment.
Applications
This power supply module is primarily utilized in legacy industrial control systems where high-reliability power regulation is required. Common applications include petrochemical refineries, power generation plants, and large-scale mining operations where S5-115U/H systems remain in active service.
Technical Specifications
Model
6ES5951-7ND21
Product Family
Simatic S5-115
Input Voltage
19.2 to 30 VDC
Output Voltage
5 VDC
Output Current (Standalone)
7 A
Output Current (With Fan)
15 A
Weight
1.6 kg
Installation Guidelines
Ensure the PLC system is completely powered down before attempting to insert or remove the module from the rack.
Verify that the mounting rail is properly grounded to the cabinet chassis to maintain EMI shielding.
When high current demands are expected, ensure the appropriate fan subassembly is installed to reach the 15 A output capacity.
Maintain adequate clearance around the module to allow for proper thermal dissipation, especially when operating at higher current loads.
Handle with care to avoid damage to the backplane connector pins during insertion.
FAQ
Does this module include a backup battery?
No, the 6ES5951-7ND21 does not include an internal backup battery. However, it is designed to support the use of a standard size C lithium battery (such as the CA-6EW1000-7AA) for memory retention within the S5-115 rack.
Can I use this module without a fan?
Yes, the module functions as a standalone power supply providing 7 A at 5 VDC without an external fan. The fan is only required if the system configuration demands the increased 15 A output capacity.
