Siemens 353 PAC Case Study

Siemens 353 Process Automation Controller (PAC) Qualified for Safety-Related Operations by ATC Nuclear

Siemens 353 Process Automation Controller

The Model 353 Process Automation Controller (PAC) is designed for a broad range of process applications. It can serve as an advanced single-loop controller or as a multi-loop controller with complete control functions, including indication, control, logic or sequencing for small unit processes.

  • Analog I/O to support dual loop or cascade control applications
  • Discrete inputs and outputs
  • Configuration via faceplate or with the iConfig Graphical Configuration software.
  • Modbus RS-485 and Modbus Ethernet communications
  • Supports function block programming language - analog process control, Boolean logic, and specialty applications

Paragon Energy Solutions has teamed up with Siemens to qualify their 353 process automation controller for safety related operations.

Paragon certifies the Siemens 353 process automation controller to be in compliance with the following standards and guidance:

Commercial Grade Dedication: conducted in accordance with EPRI NP-5652 and EPRI TR-106439.

Environmental and Seismic Qualification: conducted in accordance with specific Qualification plans based on IEEE 323 and IEEE 344. Pre-Environmental and Seismic Aging included radiation exposure aging, operational aging, accelerated thermal aging and vibrational aging. An EMC NRC RG 1.180 and EPRI TR-102323 test regimen was also completed. The specimens were subjected to a seismic test regimen including Operational Basis Earthquakes and a Safe Shutdown Earthquake in accordance with IEEE 344.

Quality Assurance Requirements: The dedication and qualification programs were conducted under ATC Nuclear’s Quality Program Manual, which complies with 10 CFR 50, Appendix B, NQA-1, and ANSI N45.2. Defects are reportable in accordance with the requirements of 10 CFR Part 21.

Product Description & Specifications

Electrical and Environmental
Power Supply
Standard: 120/240 Vac (85 to 264 Vac); 47 to 63 Hz
Optional: 24 Vdc, +20%, -15%

Power Requirements
25 watts, 50 VA (max.)

2-Wire Transmitter Power
Voltage: 25 Vdc ±3V
Current: 120 mA, short circuit protected


Analog Inputs (non-isolated)
1-5 Vdc, 4-20 mA with included 250 resistor

Digital Inputs (isolated)
0-1 Vdc OFF, 15-30 Vdc ON

Analog Input, Universal (isolated)
Thermocouple, RTD, Ohms, Slidewire, Millivolt

Digital/Frequency Input, Universal (isolated)
Frequency Range: 0 to 25,000 Hz
Minimum Operating Frequency: 0.05 Hz
ON Voltage: 4-30 Vdc
OFF Voltage: 0-1 Vdc
Input Current: <5 mA @ 30 Vdc

Analog Outputs (non-isolated)
4-20 mA into 800 ohms (max.)

Digital Outputs (non-isolated)
Open Collector Transistor
(emitter@station common)
Load Voltage: 30 Vdc (max.)
Load Current: 100 mA (max.)

Relay Outputs (SPDT) Contact Rating: 5A @ 120 Vac, 2.5 A @ 230 Vac, Resistive Load


Seismic testing of the 353 Controller on Paragon Energy Solution's tri-axial table

Product descriptions and specifications by Siemens—information is subject to change without prior notice.