Siemens SIPROTEC 5 7SL87 Line Differential and Distance Protection Relay

Siemens SIPROTEC 5 7SL87 Line Differential and Distance Protection Relay Suppliers,Exporters in India

ARP IMPEX is a supplier and exporter of Siemens SIPROTEC 5 7SL87 Line Differential and Distance Protection Relays in India. We supply against exact Siemens part-number requirements for transmission-line protection panels, utility substations, grid interconnections, power plants, panel upgrades and relay replacement projects.

The Siemens SIPROTEC 7SL87 is generally selected for important overhead lines and cable circuits where the protection scheme requires phase-selective operation. Unlike a relay limited to three-pole tripping, the 7SL87 supports both one-pole and three-pole tripping. This makes it especially relevant for transmission lines where the system needs to disconnect only the faulted phase during a single-phase fault and keep the healthy phases in service.

Line differential protection forms the main protection of the relay. Distance protection can work as backup protection or as a second main protection function. Both protection methods are available within the same platform, reducing the need for separate line differential and distance relays in the panel.

The 7SL87 can cover overhead lines, underground cables and routes containing both cable and overhead sections. It supports single-ended and multi-ended networks with up to six line terminals. Transformers and compensating coils can also remain within the protected zone when required by the scheme.

Its differential algorithm takes into account current-transformer errors, CT saturation and capacitive charging current. This is important on long cable circuits and high-voltage lines, where charging current and different CT conditions at each line end can affect protection measurements.

The minimum tripping time is 9 ms. One-pole automatic reclosing with secondary arc detection is also available, making the relay well suited to overhead transmission lines where temporary phase-to-earth faults occur.

For Siemens SIPROTEC 7SL87 price and availability, send the complete Siemens MLFB, required quantity and destination country.

Technical Specifications

• Brand: Siemens
• Product range: SIPROTEC 5
• Model: 7SL87
• Relay type: Combined line differential and distance protection relay
• Protected equipment: Overhead lines, underground cables and mixed circuits
• Main protection: Phase-selective line differential protection
• Secondary protection: Distance and directional backup protection
• Line configuration: Single-ended and multi-ended lines
• Maximum line terminals: Up to six
• Tripping: One-pole and three-pole
• Minimum tripping time: 9 ms
• Standard hardware variants: 12 predefined arrangements
• Analogue inputs: 4/4 or 8/8 current and voltage transformer inputs
• Binary inputs: 5 to 31
• Binary outputs: 8 to 46
• Hardware structure: Modular and expandable
• Housing width: From one-third to two full 19-inch rack widths
• Engineering software: Siemens DIGSI 5
• Communication: Ethernet, fibre-optic, two-wire and network options
• Communication modules: Up to four optional plug-in modules
• IEC 61850: Reporting and GOOSE communication
• Control: Circuit-breaker control, synchrocheck and interlocking
• Records: Fault, event and disturbance recording

The final I/O arrangement, housing size, communication ports and enabled protection functions depend on the complete Siemens article number.

Protection Functions

• The protection package can include:
• Phase-selective line differential protection
• Classic distance protection
• Reactance-method distance protection
• Directional overcurrent backup protection
• Phase and earth-fault protection
• Power-swing blocking
• Out-of-step protection
• Current-transformer saturation detection
• Fault location for mixed line sections
• One-pole and three-pole automatic reclosing
• Secondary arc detection
• Circuit-breaker failure protection
• Arc protection
• Voltage and frequency protection
• Underfrequency load shedding
• Directional reactive-power undervoltage protection
• Synchrocheck and switching supervision
• Trip, alarm and interlocking logic

The exact function package must be checked from the Siemens ordering code. Two 7SL87 relays can have different I/O, communication and protection arrangements even though the model name is the same.

Features

One-Pole Tripping for Transmission Lines

The 7SL87 can trip only the affected phase during a single-phase fault. This is one of the main reasons it is selected for important overhead transmission lines where system stability and continuity matter.

Differential and Distance Protection Together

Line differential protection provides fast and selective protection for the complete line section. Distance protection provides an independent backup method if differential communication is interrupted or the protection scheme requires two main principles.

Protection for Up to Six Line Ends

The relay is not restricted to a normal two-terminal circuit. It can cover tapped lines, multi-terminal transmission networks and grid interconnections with as many as six line ends.

Suitable for Long Cables

Capacitive charging-current compensation makes the relay suitable for long underground cable circuits. It can also protect mixed routes containing cable and overhead-line sections.

Accurate Fault Location

The fault-location function can calculate faults on lines with different conductor sections. This helps the maintenance team identify the affected area and reduce the time spent checking the full route.

Flexible Protection Communication

Protection data can be exchanged through optical fibre, two-wire connections and communication networks. Automatic switching between ring and chain communication arrangements is also supported.

Works in Existing Siemens Schemes

Applicable SIPROTEC 4 and SIPROTEC 5 devices can communicate within the line-protection scheme. This can help utilities that are replacing relays in stages rather than changing every line end at the same time.

Expandable Panel Hardware

The modular construction allows the relay hardware to match the actual panel. Additional inputs, output contacts and communication modules can be included for breaker control, alarms, interlocking and substation communication.

Built for Substation Automation

DIGSI 5 handles relay configuration and commissioning. IEC 61850, GOOSE messaging and optional redundant communication arrangements allow the 7SL87 to work in modern station-control systems.

Applications

• Siemens SIPROTEC 5 7SL87 Relays are used for:
• High-voltage overhead transmission lines
• Extra-high-voltage transmission lines
• Underground power cable circuits
• Mixed overhead-line and cable routes
• Single-pole transmission-line protection
• Three-pole line protection schemes
• Two-terminal transmission lines
• Multi-terminal and tapped lines
• Lines with up to six ends
• Grid interconnection lines
• Cross-country transmission lines
• Utility transmission substations
• Breaker-and-a-half substations
• Ring and meshed power networks
• Renewable-energy evacuation lines
• Wind and solar grid connections
• Lines with transformers in the differential zone
• Lines containing compensating coils
• Isolated and compensated-neutral networks
• Substation extension projects
• Line protection-panel modernisation
• Replacement of older Siemens line differential relays

The 7SL87 is mainly suited to lines where fast phase-selective fault clearing, one-pole reclosing and dependable protection communication are required. It can also provide PMU measurements and basic power-quality recording when these functions form part of the ordered configuration.

Siemens SIPROTEC 7SL86 vs 7SL87

Both relays combine line differential and distance protection and use modular SIPROTEC 5 hardware.
The key difference is the tripping arrangement:

• SIPROTEC 7SL86: Three-pole tripping
• SIPROTEC 7SL87: One-pole and three-pole tripping

The 7SL87 is therefore normally selected for overhead transmission-line schemes requiring phase-selective tripping and single-pole automatic reclosing.

The 7SL86 may be sufficient for cable circuits and applications where the scheme always trips all three phases. Selection should follow the approved protection drawing and utility specification rather than only the voltage level.

Ordering and Replacement Requirements

A quotation cannot be prepared accurately from the description “Siemens 7SL87 Relay” alone. Siemens offers different hardware and communication arrangements under this model.

Please share:

• Complete Siemens MLFB or article number
• Required quantity
• Destination country
• Required communication interface, where specified

For an existing relay replacement, send a clear photograph of the front nameplate and rear terminal arrangement. It is also important to confirm whether the relay at the opposite line end is SIPROTEC 4 or SIPROTEC 5.

If the article number is unavailable, share the existing relay model and basic line arrangement, including the number of line ends and whether one-pole tripping is required.

Siemens SIPROTEC 5 7SL87 Supplier and Exporter in India

ARP IMPEX supplies Siemens SIPROTEC 5 7SL87 Line Differential and Distance Protection Relays for utilities, transmission companies, EPC contractors, switchgear manufacturers, panel builders and industrial power projects.

We handle enquiries for Siemens 7SL87 one-pole line protection relays, multi-terminal line differential relays, overhead transmission-line protection, cable protection, IEC 61850 line relays and replacement of existing Siemens numerical relays.

The Siemens SIPROTEC 7SL87 price depends on the complete article number, I/O arrangement, communication modules, enabled protection functions and ordered quantity.

Send the Siemens part number, quantity and destination country for price, availability and export quotation.