7 Key Benefits of Using Siemens Protection Relays in Modern Substations

The Siemens protection relays, belonging to the SIPROTEC and Reyrolle series, go beyond simple fault detection to become essential components of smart grid architecture, providing the reliability, flexibility, stability, and efficiency that are key to modern substations.

Modern infrastructure demands for uninterrupted power delivery, which calls for resilient and efficient electric substations. Siemens is a global leader in power grid technology and has an extensive portfolio of industrial protection relays designed to isolate faults and protect industrial machinery.

Here, we’ll take a look at what Siemens protection relays are and the benefits they offer to modern substations.

What Are Siemens Protection Relays

Belonging to either the SIPROTEC (latest) or Reyolle (robust legacy) series, Siemens protection relays are advanced systems that are designed to detect faults and trigger protective action for connected devices in electrical substations and modern industries. This ensures reliable, safe, efficient, and continuous operations in substations, industrial plants, and grids.

Designed as compact units, these integrate complex protection, control, monitoring, and automation into a single, user-friendly interface that translates over motors to entire transmission networks.

By function, the Siemens protection relays can be of the following types:

• Siemens overcurrent relay: Detects and responds to excessive current, protecting against overloads and short circuits.
• Siemens differential protection relay: Protects transmission lines and detects internal faults.
• Siemens feeder protection relay: Designed to protect power lines/feeders in MV/HV grids.
• Siemens overvoltage/undervoltage relay: Monitors for abnormally high or low voltage levels.
• Siemens distance relay: Used for transmission line protection and to determine the distance to a fault.
• Siemens frequency relay: Designed to detect the presence of abnormal frequencies.
• Siemens directional relay: Operates based on the direction of flow of the current and is used only in conjunction with other relays.

How Do Protection Relays Function in Substations?

When installed in substations, the Siemens relay protection systems work by following the steps below:

• Monitoring and Sensing: Relays constantly watch electrical values (I, V, F) using CTs/VTs as inputs.
• Detection: If any parameter (current, voltage, frequency, phase angle, temperature, and impedance) exceeds pre-set limits, the relay detects the fault.
• Decision: The internal logic (settings) of the relay decides if the condition is a genuine fault that requires action.
• Action (Tripping): If immediate action is required, the relay sends a signal to the circuit breaker’s trip coil.
• Isolation: Once tripped, the circuit breaker physically opens, which disconnects the faulty equipment or line from the rest of the grid, isolating the problem.

Importance of Protection Relays in Substations

Protection Relays are key to the industrial setup of substations since they provide:

• Fault Detection and Isolation by detecting abnormal conditions (overcurrent, overvoltage, under-frequency) and rapidly tripping breakers to isolate the faulted section to limit damage.
• Equipment Protection for assets like transformers, generators, and motors from damage caused by faults, surges, and overloads.
• System (Grid) Stability by preventing a local fault from spreading and causing widespread outages or cascading failures.
• Personnel Safety by minimizing hazards like arc flashes through quick de-energizing of faulty equipment.
• System Reliability and Continuity ensures a smooth, uninterrupted power supply by quickly clearing temporary faults.
• Redundancy through backup protection to ensure a fault is cleared even if the main protection fails.

Siemens Protection Relay Advantages in Today’s Substations

The seven benefits of Siemens Relay Systems for modern substations are as follows:

1. High-Speed Fault Detection and Isolation

The Siemens relay protection system, such as those in the SIPROTEC series, offers a wide range of integrated functions. These include parameters like overcurrent, differential, distance, and frequency. When detected, the fault is isolated within milliseconds, which minimizes damage to the key equipment and, in turn, maintains system stability.

Relays like the SIPROTEC 7SD87 (Siemens differential protection relay) and 7SA86 (line protection relay for distance protection) can detect faults fast and ensure rapid isolation of the problem area, mitigating process disruptions and system disturbances.

2. Enhanced System Reliability and Stability

The Siemens protection relays quickly isolate faults and provide comprehensive protection functions. By swiftly isolating faulty sections of the network, these relays prevent potential hazards like electrical fires and equipment damage. This significantly improves the overall system reliability and personnel safety.

Further, these relays prevent widespread outages and maintain a stable power supply, even in challenging conditions. Additionally, the conformal coating (polyurethane-based coating) option in SIPROTEC 5 and SIPROTEC Compact devices protects these modules against moisture, corrosive gases (like H2S), dust, and mechanical stress, enhancing durability in harsh environments.

3. Scalable, Modular, and Flexible Design

The modular design of the Siemens relays allows for easy customization, expansion, and integration into both new and existing systems. For instance, the SIPROTEC 5 platform features modular hardware and software. 

This flexible design allows users to customize the relay with the exact number of inputs/outputs and functions, as needed. Thus, these can easily adapt to various substation configurations and evolving grid conditions, providing future-proofing and adaptability.

4. Advanced Communication and Support for Redundant Communication

All Siemens protection relays, including the Siemens overcurrent relay, differential protection relay, and feeder protection relay, are equipped with industry-standard protocols like IEC 61850, DNP3, and Modbus. Thus, these facilitate seamless integration with Substation Automation (SAS) and SCADA systems, enabling remote monitoring, control, and data analysis.

Further, the devices support high-availability Ethernet redundancy protocols such as Parallel Redundancy Protocol (PRP) and High-Availability Seamless Redundancy (HSR). This ensures uninterrupted communication with the connected PLC/ DCS even if a link fails.

5. Advanced Monitoring and Diagnostics

The Siemens protection relays provide valuable insights into system performance through features like detailed event logging and fault recording. They also offer extensive real-time diagnostic functions that include circuit breaker wear monitoring and power quality analysis. 

This provides valuable insights into system performance and helps in proactive maintenance. Further, this also supports data-driven decision-making, proactive maintenance, and faster troubleshooting.

6. Reduced Investment and Operating Costs

The effective protection offered by the Siemens relay protection systems can help extend the lifespan of electrical equipment present in modern substations, reducing maintenance and replacement costs. Further, their multi-functional nature also means fewer physical devices are needed, which simplifies wiring and saves space.

For example, the universal protection relays within the SIPROTEC 5 series (7SX800, 7SX82, 7SX85) allow the user to buy the minimum required functions initially. Based on the demands of the industry, additional functionalities can be ordered later, which reduces initial investment and spare parts inventory.

7. Future-Proof Technology and Cybersecurity

Designed to meet evolving industry standards, Siemens protection relays incorporate advanced features like IoT connectivity and robust cybersecurity measures to protect critical infrastructure from modern threats and adapt to the needs of digital substations and smart grids.

Protection relays like those in the SIPROTEC 5 series include robust cybersecurity features such as secure communication, authenticated network access (IEEE 802.1X), and logged security events. These help the devices comply with strict industrial standards like NERC CIP.

How Do Siemens Protection Relays Compare to Other Brands?

With multiple brands available in the market for industrial protection relays, the question often comes up as to why Siemens is a better choice than other brands. To elaborate on this, here’s a quick comparison between Siemens protection relays and those provided by other top brands:

Feature	Siemens (SIPROTEC)	ABB (Relion)	Schneider Electric
Primary Focus	High-performance, highly customizable, integrated solutions.	Broad range, strong in electrification and motion control, and advanced communication.	Reliable, scalable, integrated automation solutions with a focus on smart, IoT-enabled systems.
Product Lines	SIPROTEC 5 (advanced digital), SIPROTEC 4 (legacy), Reyrolle (robust legacy)	Relion series (comprehensive range)	MiCOM, Easergy, and Sepam series
Engineering Software	DIGSI 5 (powerful, proprietary, unified platform)	PCM600, based on the IEC 61131 open standard	Easergy Studio/MiCOM S1 Agile
Modularity and Flexibility	High degree of modular hardware/software, custom fit for applications	Good flexibility and communication integration	Scalable, integrated designs for various industrial needs
Key Strengths	Highly integrated (TIA Portal), advanced software, cybersecurity features, and PMU functionality.	Strong in power industry processes, a comprehensive portfolio, and a focus on open standards.	Cost-effective solutions, ease of use, strong in building/industrial automation integration.
Target Applications	Utility and industrial environments, medium/high voltage networks, large-scale power generation.	Comprehensive applications across power generation, transmission, and distribution.	Industrial, commercial buildings, and smart grids.

Table 1: Comparison Between Siemens Protection Relays and Those From Other Top Brands.

Wrapping Up

Offering remote monitoring, complete digitalization, and predictive maintenance through scalable and modular hardware, Siemens protection relays are an essential part of modern substations. They also offer smart grid integration and are backed by global service and technical support, which makes them reliable devices.

Siemens Protection Relays as a Top Choice for Modern Substations

Establishing a new electrical substation or upgrading an existing one? Choose Siemens protection relays that deliver performance and safety. 

Frequently Asked Questions

How Do Siemens Relays Optimize Substation Performance in Substations?

Siemens protection relays combine protection, monitoring, control, and automation in a single device, which simplifies operations. The rapid fault detection and isolation, IoT compatibility, power quality monitoring, and predictive maintenance through data analytics (MindSphere) help optimize substation performance.

What Distinguishes Siemens Protection Relay Systems From Others?

Siemens devices offer high reliability, ultra-fast tripping times (e.g., <15 ms for busbar protection), comprehensive functionality within a single unit, along with advanced cybersecurity features and long-term support with backward compatibility. This gives the devices an edge over other industrial brands in the market.

How Do Siemens Protection Relays Enhance Substation Safety?

The Siemens relay protection systems provide rapid and reliable fault detection, device isolation, and monitoring. This prevents equipment damage, fire hazards, and cascading power outages.

Do the Relays Offer Remote Monitoring and Control Capabilities? 

The Siemens protection relays provide remote monitoring and control, supporting various communication protocols (e.g., Modbus TCP, DNP3, IEC 60870-5-104) to allow integration with Substation Automation Systems and remote operation centers.