Description
Schneider Electric SEPAM G87 Generator Protection Relay
Product Overview
The Schneider Electric SEPAM G87 is a Series 80 numerical protection relay designed specifically for generator protection. Unlike a general feeder relay, the G87 combines generator-specific protection functions with measurement, breaker control, event recording, waveform capture, communications, and programmable logic capabilities. Schneider identifies G87 as one of the Series 80 generator protection models alongside G88. The platform is intended for generator applications where current and voltage protection must be coordinated with generator operating conditions and breaker control.
The SEPAM G87 can provide current, voltage, frequency, differential, directional power, underimpedance, volts-per-hertz, synch-check, and multiple earth-fault functions. Schneider’s Series 80 documentation also identifies native breaker control, zone-selective interlocking, waveform capture, event recording, load shedding/motor restart functions, and optional Logipam programmable logic.
A critical procurement point is that G87 is an application designation, not a complete hardware configuration. Schneider’s ordering structure begins with SQ1G87 and then specifies display, CT input arrangement, I/O, communications, analog output, Logipam, and synch-check options. A documented example is SQ1G87P1J5A0B0, which specifies a G87 generator relay with MimicBus display, 1/5 A CT inputs, a 14-input/11-output digital module, two RJ-45 ports, and Logipam firmware.
Product Introduction
Generator protection requires more than conventional phase overcurrent. The SEPAM G87 combines differential, voltage, frequency, power, impedance, and synchronization-related functions within the Series 80 architecture, allowing one protection IED to cover a broad generator protection scheme.
For a legacy replacement, do not order solely from the words “G87.” Match the complete SQ1G87... order code, CT arrangement, digital I/O module, communication option, display, Logipam configuration, synch-check option, and existing protection settings.
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Product Model | SEPAM G87 |
| Manufacturer | Schneider Electric |
| Product Family | Easergy Sepam Series 80 |
| Application | Generator protection |
| Product Type | Numerical generator protection relay |
| Main Protection | Generator current, voltage, frequency and differential protection |
| Differential Protection | Generator differential protection available |
| Current Inputs | 1 A / 5 A configurations available |
| Voltage Inputs | Available according to G87 configuration |
| Digital Inputs | Series 80 architecture supports up to 42 logic inputs |
| Relay Outputs | Series 80 architecture supports up to 23 relay outputs |
| Temperature Inputs | Up to 16 with applicable Series 80 modules |
| Communications | Modbus RTU, Modbus TCP/IP, IEC 61850 options |
| IEC 61850 | MMS; GOOSE available with applicable configuration |
| Ethernet | RJ-45 communication interfaces on applicable configurations |
| Display | Standard, advanced, or MimicBus options depending on order code |
| Programming | Logipam optional |
| Synch-Check | Optional module for ANSI 25 |
| Memory | Removable memory cartridge for parameters/settings |
| Installation | Protection-panel / switchgear application |
| Firmware | Configuration-dependent |
| Lifecycle | Legacy Series 80 platform; individual catalog references may be discontinued |
Schneider states that the Series 80 platform provides 12 analog inputs in configurable current/voltage arrangements, 42 logic inputs, 23 relay outputs, two Modbus communication ports, and up to 16 temperature-sensor inputs when the applicable modules are installed. These should be regarded as Series 80 architecture capabilities rather than guaranteed I/O on every G87 unit.
The G87 protection-function set includes ANSI functions such as 21B underimpedance, 24 volts/hertz, 25 synch-check, 27 undervoltage, 32P directional power, 46 negative-sequence current, 50/51 phase overcurrent, 50N/51N ground overcurrent, 59 overvoltage, 67/67N directional overcurrent, 81H/81L over/underfrequency, and related generator functions. Exact availability can depend on configuration and application settings.
SEPAM G87
Major Features and Practical Advantages
1. Generator-specific protection architecture
The G87 is purpose-configured for generator applications rather than being a feeder relay with a generator label. Schneider’s published function matrix includes generator-relevant differential, underimpedance, volts-per-hertz, directional power, synch-check, voltage, frequency, and current protection.
That makes the relay particularly relevant to medium-voltage generator switchgear where multiple protection elements must coordinate around generator operating characteristics.
2. Generator differential protection
Differential protection is one of the important distinctions between the G87 and more basic overcurrent relays. The G87 configuration can provide generator differential protection, allowing internal generator faults to be distinguished from external network faults when the CT scheme is correctly engineered.
CT ratio, polarity, wiring, saturation performance, and protection settings must all be checked during replacement. A relay with the correct model number but incorrect CT configuration is not a valid commissioning result.
3. Voltage and frequency protection
Generator protection frequently requires supervision of operating conditions beyond current magnitude. The G87 function set includes phase and sequence voltage protection together with overfrequency, underfrequency, and rate-of-change-of-frequency functions.
These functions can participate in generator trip, alarm, load-shedding, or control schemes depending on the application logic.
4. Volts-per-hertz protection
The G87 includes ANSI 24 volts-per-hertz protection. This is relevant to generator and transformer overexcitation conditions where excessive V/Hz can produce damaging magnetic flux levels.
The actual pickup, delay, and trip logic should always be taken from the site’s approved protection study rather than copied from a generic G87 template.
5. Synch-check capability
ANSI 25 synch-check is available through the applicable G87 configuration. Schneider’s ordering guide identifies an MCS025 Sync-Check Module for the ANSI-25 function.
This is an optional hardware/configuration point, so do not assume every G87 has synch-check installed merely because the function appears in the family documentation.
6. Generator breaker control
Schneider identifies built-in circuit-breaker control as a G87 feature. The relay can therefore participate in the generator breaker operating scheme rather than serving solely as a passive trip device.
During a replacement, document breaker-control outputs and interlocking logic before removing the existing relay. This is particularly important when Logipam or custom logic is installed.
7. Event and waveform recording
The G87 supports event recording and waveform capture, providing useful information for post-trip analysis. Schneider also identifies onboard data logging within the Series 80 generator application.
For maintenance teams, the old relay’s disturbance records can be valuable evidence. Export required records before replacement when the relay remains accessible and operational.
8. Flexible communications
Series 80 supports Modbus RTU, Modbus TCP/IP, and IEC 61850 communications, with IEC 61850 configurations supporting MMS and, where configured, GOOSE.
The communication protocol is not determined by the word “G87” alone. The complete catalog number and installed communication option must be checked before assuming Ethernet or IEC 61850 functionality.
9. Removable memory cartridge
Schneider identifies a removable memory cartridge containing parameters and settings as part of the Series 80 architecture. This can simplify replacement and commissioning when the correct configuration is transferred according to the manufacturer’s procedure.
Do not treat memory-cartridge transfer as a substitute for verifying CT/VT wiring, protection settings, logic, communications, and firmware after replacement.
Related Products
- SEPAM G88 — Advanced generator protection model in the same Series 80 family, with additional generator/transformer application capability.
- SEPAM G82 — Earlier Series 80 generator protection model for generator applications.
- SEPAM M87 — Motor protection relay in the Series 80 family; shares the high-level platform architecture but is configured for motor protection.
- SEPAM M88 — Advanced motor protection relay with broader motor/application capability.
- SEPAM T87 — Transformer differential and protection relay in the Series 80 family.
- SEPAM S84 — Advanced substation/feeder protection relay using the same Series 80 architecture.
- SEPAM B80 — Busbar protection relay for Series 80 applications.
- SEPAM B83 — Busbar protection model with broader protection functions.
- MCS025 — Synch-check module identified by Schneider for applicable Series 80 ANSI-25 configurations.
- MET1482 — Temperature-input module used in applicable Series 80 configurations.
FAQ
What is SEPAM G87?
SEPAM G87 is a Schneider Electric Easergy Sepam Series 80 generator protection relay. It is designed for generator protection and control, with functions covering current, voltage, frequency, differential, power, impedance, and synchronization-related protection.
Is G87 a PLC or DCS I/O module?
No. It is a power-system protection IED. It can contain programmable logic and communicate with supervisory systems, but its primary role is generator protection, measurement, monitoring, and breaker/control functions.
Does every G87 have IEC 61850?
No. IEC 61850 is an available communications option/configuration. Schneider’s ordering information shows that the exact communication hardware and protocol depend on the complete SQ1G87... configuration.
Does every G87 include synch-check?
No. Schneider identifies the MCS025 module as the module required for ANSI-25 synch-check in applicable configurations. Therefore, verify the complete order code and installed hardware before assuming synch-check is available.
Can I hot-swap a SEPAM G87?
Do not assume hot-swap operation. This is a protection relay connected to CT, VT, breaker-trip, and potentially generator control circuits. Proper electrical isolation and the approved switchgear maintenance procedure are required before removing the relay.
Does G87 support generator differential protection?
Yes. Schneider’s G87 documentation identifies generator differential protection as a core application function, and the published typical catalog configuration is explicitly described as Generator Differential Protection G87.
Can I replace an old G87 with any SQ1G87 relay?
Not safely based on the G87 designation alone. Compare the complete SQ1G87... catalog number, CT inputs, display, digital I/O module, communication hardware, Logipam option, synch-check module, and protection settings. Schneider’s ordering table demonstrates that these options can differ substantially between G87 configurations.
Does G87 retain the protection settings after replacement?
The Series 80 architecture uses a removable memory cartridge containing parameters and settings. However, replacement should still include verification of all protection parameters, logic, CT/VT ratios, communication settings, and breaker-control configuration rather than assuming a memory transfer is sufficient.
Is SEPAM G87 still commercially available?
Schneider’s catalog shows legacy G87 references as discontinued. For example, Schneider lists catalog reference 59741 as discontinued and states that after-sales services such as repair and spare-parts support continue until the applicable end-of-life point. The exact status depends on the catalog reference.
Procurement Note
The Schneider Electric SEPAM G87 is a specialized generator protection IED, and the short designation does not define the complete hardware. Schneider’s Series 80 ordering structure uses SQ1G87 followed by configuration characters for display, CT input type, I/O, temperature inputs, analog output, Logipam, and synch-check.
For a replacement purchase, record the complete catalog number from the relay nameplate before ordering. Also capture the installed firmware, memory-cartridge configuration, CT/VT ratios, protection settings, communication protocol, IEC 61850 configuration if present, breaker-control logic, and any Logipam application.
For New Surplus or previously installed equipment, inspect the current transformer and voltage transformer terminals, digital I/O connectors, communication ports, display, memory cartridge, and front-panel condition. A clean housing does not establish that the relay contains the correct application or firmware.
One particularly important point: do not substitute a G88, M87, T87, or another Sepam 80 model simply because the physical platform looks similar. Schneider assigns each Series 80 model to a defined protection application. The G87 is specifically the generator relay.
For legacy generator protection, the correct procurement strategy is to match SEPAM G87 + complete order code + hardware options + firmware/configuration + protection settings, then validate the replacement through the site’s approved relay-testing procedure.
