Siemens SIPROTEC 5 Replacement and Upgrade Guide

Siemens SIPROTEC 5 Replacing Old Protective Devices: A Complete Guide to Migrating from SIPROTEC 4

Introduction: Why is it necessary to replace old protective devices

In the field of power system protection, the discontinuation of old protection devices, shortage of spare parts, and increasingly strict network security requirements are forcing operation and maintenance teams to seek modern upgrade solutions. The old modules of brands such as Woodward and Honeywell are facing the same dilemma, while the Siemens SIPROTEC 4 series is gradually being replaced by the new generation SIPROTEC 5. SIPROTEC 5 is based on a modular hardware and software platform, providing stronger protection functions, more flexible communication, and more comprehensive network security mechanisms. However, directly replacing the running SIPROTEC 4 device is not a simple "plug and play" - it is necessary to ensure that the line differential protection topology is not interrupted during the replacement process, and that the new and old devices can operate in a mixed manner. This article is based on Siemens' official technical documentation and elaborates on how to replace SIPROTEC 4 equipment with SIPROTEC 5, covering compatibility, hardware selection, engineering configuration, testing, and common troubleshooting.

Part 1: Compatibility Fundamentals of SIPROTEC 5 and SIPROTEC 4

1.1 Feasibility of Mixed Operations

Starting from firmware version V7.90, the SIPROTEC 5 line protection device supports mixed configuration with SIPROTEC 4 series devices for the first time. This means that during the replacement process, there is no need to replace all devices at once, and it can be gradually migrated. The two main application scenarios are as follows:

Scenario 1: Replace individual devices in the existing topology

Functionally remove an old SIPROTEC 4 device from the differential protection topology and upgrade it to SIPROTEC 5, while keeping the remaining devices in their original state, the entire differential protection can still operate normally.

Scenario 2: Expanding the existing SIPROTEC 4 topology

Add SIPROTEC 5 devices (supporting up to 6 endpoints) to the existing SIPROTEC 4 topology, enabling the system to have future scalability.

1.2 Supported Old Device Versions

According to Siemens technical documentation, the following SIPROTEC 4 models can be mixed with SIPROTEC 5 (V7.90 and above) for operation:

7SA522 / FF 4.70

7SA6 / EE 4.70

7SD52 / 53 / EE 4.70

7SD610 / DD 4.70

Earlier firmware versions are theoretically feasible, but have not been officially tested by Siemens. Therefore, before replacement, it is recommended to prioritize upgrading the SIPROTEC 4 device to the recommended version mentioned above.

1.3 Compatibility of Protection Interface Modules

Protection communication is the key to implementing differential protection and directional comparison protection for transmission lines. The existing communication converter on the SIPROTEC 4 side can be retained and only needs to be adapted on the SIPROTEC 5 side. The specific module requirements are as follows:

The SIPROTEC 5 side requires the use of USART-AD-1FO or USART-AE-2FO FOS modules, which can be directly connected via fiber optic cables.

For communication networks that comply with the IEEE C37.94 standard, subsequent versions will support the FO30 module.

When connecting long-distance modules FO17, FO18, and FO19, a suitable signal repeater should be used on the SIPROTEC 5 side.

This design allows users to utilize existing fiber infrastructure, significantly reducing replacement costs.

Part 2: Hardware Replacement Plan and Selection of Standard Variants

2.1 Understanding the modular hardware of SIPROTEC 5

SIPROTEC 5 equipment is divided into two categories:

Non modular devices (7xx82): such as 7SJ82, 7SA82, 7SD82, with a fixed width of 1/3 x 19 inches, cannot add expansion modules, but provide multiple pre configured standard variants.

Modular devices (7xx85/86/87 and 6MD8): such as 7SJ85, 7SA86, 7SD87, etc., support flexible increase in I/O volume through 1/6 width expansion modules, can configure up to 2 rows of hardware, and achieve up to 40 analog channels and over 200 binary I/O.

2.2 Standard variant selection for replacing SIPROTEC 4

For example, replacing the common SIPROTEC 4 line protection (such as 7SA6) with SIPROTEC 5 distance protection (7SA86), the following standard variants are recommended:

Recommended SIPROTEC 4 configuration: SIPROTEC 5 model standard variant binary input/output CT/VT quantity

Single CT, single VT, small amount of I/O 7SA86 Type 1 (1/3) 7 BI/14 BO 4I+4V

Multiple I/O requirements 7SA86 Type 8 (2/3) 31 BI/46 BO 4I+4V

Double circuit breaker wiring (breaker-a-half) 7SA86 Type 11 (5/6) 27 BI/33 BO 8I+8V

2.3 Current Transformer Terminals and Safe Replacement

SIPROTEC 5 adopts innovative "Safety CT Plug" technology. When replacing equipment, pulling out the current terminal will always keep the secondary circuit closed, completely avoiding the risk of CT open circuit. This feature is particularly important for uninterrupted replacement of old equipment. In addition, the rated value of the current transformer (1A/5A) can be electronically configured through software without the need to turn on the device or adjust jumpers.