GE Multilin 350‑L‑P5‑G5‑H‑E‑E‑N‑N‑SN‑D‑N Feeder Protection Relay

Product Description

350‑L‑P5‑G5‑H‑E‑E‑N‑N‑SN‑D‑N is a member of GE Multilin 350 series intelligent feeder protection relay, configured for 5A phase current input, 5A ground current input, draw‑out housing, standard power supply, enhanced I/O set, without local HMI display, SN suffix indicates standard hardware build, D‑N defines communication and option configuration. This multifunctional device integrates protection, metering, control, event recording and fault oscillography functions, designed for medium‑voltage switchgear feeder circuits, providing ANSI‑standard protection elements for overcurrent, earth‑fault, phase‑to‑phase short‑circuit and breaker failure conditions. It supports Modbus RTU, Ethernet communication for SCADA integration, and operates in harsh substation cabinet environments with wide temperature tolerance.

Product Features

• Complete ANSI protection function suite: phase overcurrent, neutral ground overcurrent, negative‑sequence overcurrent, breaker failure protection, voltage‑based protection elements
• 5A secondary current input for phase and ground channels, compatible with standard instrument current transformers
• Draw‑out pluggable housing design, support hot‑removal for convenient maintenance and spare‑part replacement without cabinet wiring modification
• Rich digital input / relay output resources for breaker status acquisition, trip‑close control, alarm output and interlock logic
• Fault oscillography, sequence‑of‑events (SOE) recording, fault‑report storage for post‑fault analysis
• Metering function for three‑phase current, voltage, power, energy, demand value, supporting local and remote reading
• Multi‑protocol communication: Modbus TCP/IP, Modbus RTU for connection to DCS and substation SCADA system
• No front‑panel local display variant; configuration and monitoring completed via front port or network software
• Wide operating temperature range ‑40 °C ~ +60 °C, meets IEC‑61000 series EMC anti‑interference requirements for power‑substation
• Breaker control logic, configurable 86 lock‑out function, programmable logic for user‑defined interlock conditions

Application Scenarios

• Medium‑voltage 6‑35kV switchgear feeder protection for power plant auxiliary system and industrial substation
• Distribution network substation incoming‑feeder and outgoing‑feeder overcurrent & earth‑fault protection
• Motor feeder and transformer backup protection for petrochemical, chemical and mining industrial power system
• Indoor MV switch‑cabinet installation where local HMI display is not required, centralized remote monitoring mode adopted
• Retrofit project for legacy GE Multilin protection devices, spare‑part replacement of existing 350‑series installed base
• Power system requiring fault waveform recording, SOE event log and remote SCADA data uploading function

Common Problems & Troubleshooting

• Relay cannot power‑on after insertion: Check rated control power supply voltage (AC/DC range); inspect draw‑out back‑plane connector full engagement; clean gold‑finger contacts; check cabinet power circuit fuse status.
• No communication with configuration software: Verify communication port parameter, baud‑rate, slave address match setting; check Ethernet cable or RS485 wiring; confirm no duplicate address within same network segment.
• False tripping or unwanted protection operation: Review protection setting group; check CT wiring polarity and secondary‑circuit grounding condition; inspect transient interference in substation environment; verify negative‑sequence and ground‑current setting value.
• Metering value obviously deviate actual value: Confirm CT ratio and VT ratio parameter setting; inspect loose wiring at CT secondary terminal; check open‑circuit risk on current‑transformer secondary loop.
• SOE or fault oscillography cannot be read: Confirm relay internal time synchronization; check storage resource status; upgrade firmware version if file parsing error occurs.
• Digital input status not updated: Check field loop power supply; inspect dry‑contact wiring continuity; verify input threshold setting matches field signal level.
• Spare‑part replacement mismatch risk: Strictly match full ordering code 350‑L‑P5‑G5‑H‑E‑E‑N‑N‑SN‑D‑N; different suffix letters represent different I/O, power‑supply and communication options; wrong variant will cause function missing.