Product Overview

The GE Multilin 750-P5-G5-S5-HI-A1-R-E-H​ is a microprocessor-based feeder management relay from the well-known 750/760 Feeder Management Relay​ platform (also referenced as the SR750 series), designed to deliver complete protection, control, metering and monitoring for medium-voltage utility and industrial distribution feeders. In a single drawout case, the 750-P5-G5-S5-HI-A1-R-E-H​ combines phase, ground and sensitive ground overcurrent elements with voltage, frequency, directional, breaker-failure and synchronism-check functions, so a single device replaces what used to require a panel full of discrete electromechanical relays. By continuously sampling the current and voltage waveforms and executing high-speed trip logic, it isolates faulted cable sections and transformers before thermal damage accumulates, and it records what happened so engineers can prove it afterwards.The order code of the 750-P5-G5-S5-HI-A1-R-E-H​ defines its exact factory build, and reading that code is the fastest way to understand the device. P5 specifies 5 A phase current inputs, G5 specifies 5 A zero-sequence (ground) current inputs, and S5 specifies a 5 A sensitive ground input — the third channel being the one that makes low-magnitude, high-impedance earth faults on cable feeders detectable at all. HI defines the wide-range control power supply (88 to 300 V DC, 70 to 265 V AC at 48 to 62 Hz), which lets the same unit run from a 125 V or 250 V station battery or from an AC auxiliary supply without a variant change. A1 provides the analog output channel set (0–1 mA class), R gives a red breaker-closed LED for unambiguous local status, E denotes the enhanced display — the larger backlit LCD and improved keypad introduced with the V6.00 generation — and H is the harsh-environment option, meaning the internal boards carry a factory-applied conformal coating.In system terms, the 750-P5-G5-S5-HI-A1-R-E-H​ sits at the primary protection layer of a feeder bay and doubles as an intelligent electronic device (IED) for SCADA. It presents measured values, breaker status, trip counters, sequence-of-events records and oscillography over RS232, RS485 and Ethernet using Modbus RTU/TCP and DNP 3.0, and it is configured and commissioned through GE’s EnerVista 750/760 Setup software. Because it communicates as comfortably as it protects, it is equally at home in a utility substation, an industrial switchgear lineup, or a brownfield panel where an ageing electromechanical scheme is being upgraded one bay at a time.

Technical Specifications

Main Features and Advantages

Three independent current channels, including a genuinely sensitive ground path: The P5, G5 and S5 options on the 750-P5-G5-S5-HI-A1-R-E-H​ are not redundant copies of the same input. Phase currents feed overcurrent, negative-sequence and directional elements; the standard ground input handles solid and low-impedance earth faults; and the sensitive ground channel is what detects the low-level, often intermittent earth faults typical of high-impedance grounded and cable-heavy networks. In practice, this is the difference between a relay that trips on a fault and a relay that sees the fault developing — arcing insulation, moisture ingress, a deteriorating cable joint — before it escalates into a feeder outage.One relay, an entire protection panel: The 750-P5-G5-S5-HI-A1-R-E-H​ carries an unusually broad ANSI function set — 50/51 phase, ground and sensitive ground, 67 directional variants, 46 negative sequence, 27/59 voltage, 81 frequency, 32 reverse power, 25 synchronism check and 50 breaker failure — plus metering, demand logging, breaker wear monitoring and programmable logic. Consolidating these functions into one IED reduces panel wiring, removes inter-relay coordination wiring errors, and gives protection engineers a single settings file to manage, version and audit instead of a dozen dial-setting sheets.Engineering and commissioning features that save real hours: With the E option, the 750-P5-G5-S5-HI-A1-R-E-H​ presents a 40-character backlit display and a logically grouped keypad, so a technician can read measured values, actual setpoints and fault messages without a laptop. Through EnerVista 750/760 Setup, the same engineer gets dual-cursor oscillography with delta measurement, zoom and playback for precise post-fault analysis, quick-connect serial setup, and the ability to configure multiple relays from one workspace. Four independent setting groups allow the same hardware to cover normal, emergency, seasonal and maintenance operating modes without re-downloading settings.Built for the environment it actually lives in: The H suffix on the 750-P5-G5-S5-HI-A1-R-E-H​ means the internal assemblies are conformal coated at the factory. That transparent polymer barrier protects against conductive dust, humidity, salt spray and the mildly corrosive atmospheres found in chemical plants, pulp and paper mills, wastewater facilities, mines and offshore platforms — environments where an unprotected relay board slowly loses reliability long before it visibly fails. Combined with the wide-range HI control supply, which tolerates the full span of a station battery from equalise charge down to end-of-discharge, and a −40 °C to +60 °C operating range, the unit is specified for the real conditions of outdoor switchgear and industrial substations rather than for a laboratory bench.