GE 750-P5-G5-HI-A1-R-E Protection Relay – Multilin 750 Series

GE Multilin 750-P5-G5-HI-A1-R-E: Feeder Management Relay for Medium-Voltage Protection Systems

The GE Multilin 750-P5-G5-HI-A1-R-E is a full-function feeder management IED (Intelligent Electronic Device) engineered for medium-voltage distribution networks operating between 1 kV and 38 kV. Within a protection control loop, this relay occupies the primary decision layer: it continuously samples current and voltage waveforms at 64 samples per cycle, applies configurable ANSI protection algorithms in firmware, and issues trip or reclose commands to the associated circuit breaker within 8–16 ms of fault detection — well within the sub-cycle response window demanded by modern arc-flash mitigation schemes.

The suffix string P5-G5-HI-A1-R-E encodes the hardware build precisely. P5 designates 5 A nominal phase CT inputs; G5 designates a dedicated 5 A ground CT input channel with independent burden and saturation characteristics. HI is the high-speed communications daughterboard, providing RS-485 physical layer with simultaneous Modbus RTU and DNP3 Level 2 protocol support. A1 is the standard output relay matrix — four Form-C trip/close contacts rated at 10 A continuous, 30 A make. R is the wide-range redundant auxiliary power supply accepting 24–250 V DC or 100–240 V AC without jumper changes. E specifies English-language firmware and HMI labeling.

This relay is stocked and dispatched from Xiamen, China, with full export documentation. All units pass a structured incoming inspection before listing. 12-month warranty is included as standard.

📧 Real-time Stock & RFQ: [email protected] | WhatsApp: +86 18359268345

Technical Parameters

Hardware Logical Analysis

The 750-P5-G5-HI-A1-R-E is built on a modular backplane architecture that separates analog signal conditioning, digital processing, and communications into discrete PCB layers — a design discipline that directly reduces inter-subsystem noise coupling.

Analog Front-End & Optical Isolation: Phase and ground CT inputs pass through dedicated burden resistors and anti-aliasing filters before entering a 16-bit sigma-delta ADC array. Each analog channel is galvanically isolated from the digital processing domain via optocoupler barriers rated at 2.5 kV RMS, preventing CT saturation transients or ground potential rise events from propagating into the microprocessor bus. This isolation architecture meets IEC 60255-27 insulation class III requirements.

Dual-Processor Architecture: Protection algorithms execute on a dedicated real-time DSP core clocked independently from the HMI and communications processor. This hard partitioning ensures that a communications bus collision or HMI polling event cannot introduce latency jitter into the protection execution cycle — a critical requirement for 50-element instantaneous overcurrent functions where pickup-to-trip latency must remain deterministic at ≤ 16 ms.

EMC Design: The chassis employs a multi-layer ground plane strategy with separate analog and digital ground domains joined at a single star point. All I/O terminals are filtered with common-mode chokes and transient voltage suppressors (TVS) rated to IEC 61000-4-5 Level 4 (4 kV surge). The enclosure achieves IEC 61000-4-3 radiated immunity at 10 V/m across 80 MHz–1 GHz — sufficient for installation adjacent to high-frequency switching drives and arc-flash detection systems.

Wide-Range Power Supply (R Suffix): The auxiliary supply module uses an active power factor correction (PFC) front-end followed by a flyback converter with galvanic isolation. The 24–250 V DC acceptance range is achieved without mechanical jumpers by an auto-ranging input stage, eliminating field configuration errors during substation commissioning. Hold-up time exceeds 50 ms at full load, bridging momentary auxiliary supply interruptions without relay reset.

Output Relay Contact Architecture: Trip contacts use bifurcated silver-alloy contacts with gold flash on the contact surface, maintaining reliable make/break performance at low-current dry-circuit levels (1 mA, 5 V DC) while retaining the 30 A make rating required for direct breaker trip coil driving. This dual-rating design eliminates the need for interposing relays in most applications.

System Integration Benefits

• Deterministic Protection Execution: Hard-partitioned DSP architecture guarantees ≤ 16 ms pickup-to-trip latency for 50-element functions, independent of communications or HMI load — a prerequisite for arc-flash mitigation zone selectivity.
• Simultaneous Dual-Protocol SCADA: The HI module runs Modbus RTU and DNP3 Level 2 concurrently on the same RS-485 port, allowing legacy SCADA masters and modern DNP3 RTUs to coexist on the same communications segment without protocol gateways.
• Directional Earth Fault Detection (67N): Polarized ground overcurrent element uses zero-sequence voltage reference, enabling selective fault clearance on compensated (Petersen coil) or high-impedance earthed networks where non-directional relays produce nuisance trips.
• Integrated Reclosing Logic (79): Configurable 4-shot reclosing with independent dead-time and reclaim-time settings per shot, reducing sustained outage duration on overhead feeder networks by automatically restoring supply after transient faults.
• Sync-Check (25) for Automatic Bus Transfer: Built-in synchrocheck element monitors voltage magnitude, phase angle, and frequency differential across the breaker, enabling safe automatic bus transfer without external sync-check relays.
• High-Resolution Oscillography for Post-Fault Analysis: 15 fault records at 64 samples/cycle provide waveform data sufficient for CT saturation analysis, fault impedance calculation, and protection coordination review — reducing post-fault investigation time from days to hours.
• IRIG-B Time Synchronization: Microsecond-accurate event timestamping via IRIG-B input enables precise sequence-of-events reconstruction across multiple IEDs in a substation, critical for protection coordination audits and regulatory reporting.
• Breaker Failure Detection (50BF): Integrated breaker failure element monitors trip coil current continuity and initiates backup trip to upstream breaker within a configurable timer (typically 150–200 ms), eliminating the need for a separate 50BF relay in most feeder protection schemes.

Quality Assurance & Global Logistics

Every GE Multilin 750-P5-G5-HI-A1-R-E unit dispatched from our Xiamen facility has passed a structured incoming inspection covering physical authenticity verification (label, holographic seal, PCB markings cross-referenced against GE Multilin reference documentation GEK-106310), functional power-on test including communications handshake and output relay actuation, and documentation assembly including Certificate of Conformance and high-resolution pre-shipment photographs.

Units are packed in anti-static foam inserts inside double-wall corrugated cartons, with the relay secured against 6-face drop per ISTA 2A transit testing protocol. Original GE Multilin factory packaging is preserved where available. Export documentation includes commercial invoice, packing list, country-of-origin declaration, and HS code 8536.49 classification for smooth customs clearance in all major import markets.

Shipping options from Xiamen: DHL Express (3–5 business days globally), FedEx International Priority, and sea freight consolidation for multi-unit orders. EXW and FOB Xiamen Incoterms are available for freight-forwarder customers. In-stock units ship within 1–2 business days of order confirmation. A 12-month warranty against defects in materials and workmanship is included with every unit, with replacement or full refund processed within 5 business days of fault confirmation — no dispute process required.

Contact Information

📧 Email: [email protected]
💬 WhatsApp: +86 18359268345
🌐 Web: siemensplc.com
📍 Location: Xiamen, China
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