Description

Key Technical Specifications

Parameter	Specification
Product family	GE MIF-II digital feeder relay
Protection scope	Feeder, transformer, bus, generator, motor backup
Rated voltage	AC rated voltage
Rated current	AC rated current
Auxiliary supply	DC auxiliary supply
Outputs	Configurable outputs (trip, service, auxiliary)
Communication	RS-232 front, RS-485 rear, Modbus RTU
Configuration software	EnerVista compatible
Display	Character LCD with configurable LEDs
Protection functions	Phase/ground TOC & IOC, thermal overload, cold load pickup, auto-recloser
Environment	Wide operating temperature range; non-condensing humidity
Dimensions	Compact DIN/panel-mount form factor

Product Introduction

MIFIIPI55E10HI00 is one of those GE MIF-II relays you still see sitting in older switchgear rooms where nobody wants to touch the protection settings unless absolutely necessary. It handles feeder overcurrent, ground fault, thermal overload, and breaker control without needing a full modern IED retrofit. I’ve seen these used on feeder circuits where the plant just needed reliable TOC/IOC protection and Modbus RTU visibility back to the SCADA server.Engineers keep these in stock because they are simple, configurable, and don’t require a full system migration. The wide-range DC supply helps it survive rough auxiliary power conditions, and the EnerVista software makes setting changes tolerable. Just don’t assume every suffix code means the same I/O set; the option portion can carry option-dependent features, so always confirm the exact trip outputs and communication ports on the physical label.

Quality SOP & Tech Pitfalls

The Lab Report (SOP)

Visual and counterfeit check: nameplate, model code, serial number, mounting clips, terminal condition.
Live test on test rack: apply DC auxiliary supply and verify LCD/LED boot sequence.
Meter checks: verify RS-232/RS-485 port presence, output contact continuity, and insulation resistance with a Fluke 115 or equivalent.
Firmware and settings review: confirm EnerVista communication, firmware readability, and stored fault records.
Final seal: anti-static bag, desiccant, and reinforced carton with photos of nameplate and test results.

The Engineer’s Warning (Pitfalls)

Wrong suffix assumption. MIF-II relays ship with different option codes. If you order MIFIIPI55E10HI00 without confirming the output count and communication ports, you can end up with a relay that physically fits but doesn’t match the trip matrix.
Lost settings. I once saw a plant swap a feeder relay, power it up, and realize nobody saved the old pickup values, time curves, or Modbus address. The relay booted fine. The feeder did not. Always export the EnerVista file and photograph the front-panel settings before removal.

Installation & Configuration Guide

Pre-Installation: ️ De-energize the feeder and auxiliary supply. Wait for capacitor discharge. Photograph the existing relay settings, wiring labels, Modbus address, and trip assignments.
Removal: Label every trip, alarm, CT, VT, and communication wire. Remove terminal blocks carefully. Release the mounting clips without forcing the panel cutout.
Installation: Copy all old settings into the new relay before energizing. Confirm CT ratio, pickup current, time curve, auto-reclose mode, Modbus address, baud rate, and output assignments. Seat the relay firmly and reconnect labeled wires.
Power-On & Testing: Apply DC auxiliary supply. Check LCD startup, LED indicators, and fault memory. Verify RS-485 communication with EnerVista or the SCADA master. Perform secondary injection or functional trip testing before returning the feeder to service.

Compatible Replacement Models

Drop-in Replacement: Another GE MIF-II relay with identical suffix code and option set. Same mounting, I/O, and EnerVista configuration.
️ Software Compatible: Other MIF-II variants with different suffix codes. Hardware may match, but settings, output mapping, and firmware may need reconfiguration in EnerVista. Plan engineering review time for validation.
Hardware Mod Required: Modern GE Multilin or third-party IEDs. These may offer better protection features but usually require new wiring, CT/VT scaling, communication mapping, and panel modification. Do not attempt unless a full upgrade is approved.

Frequently Asked Questions (FAQ)

Q: Can I hot-swap this relay on a live feeder?
No. Treat it as a de-energized replacement unless your site has an approved live-work procedure and redundant protection. Trip outputs can energize during power-up if settings are wrong.Q: Is MIFIIPI55E10HI00 still in production?
It is generally considered a legacy GE MIF-II relay. Most available units are new surplus or inventory stock. Confirm condition and firmware before purchase.Q: Does it work with EnerVista?
Yes. The MIF-II family is compatible with EnerVista for configuration, monitoring, and setting management.Q: What supply voltage does it accept?
The relay supports a wide-range DC auxiliary power supply. Do not apply AC auxiliary voltage unless the OEM nameplate explicitly allows it.Q: Can I use it for motor or transformer protection?
It can serve as backup protection for motors, transformers, buses, and generators, but it is primarily a feeder relay. For dedicated motor or transformer schemes, verify thermal models and CT requirements.Q: What communication does it support?
Front RS-232 and rear RS-485 with Modbus RTU. Confirm the physical port layout on your unit before running communication cables.