onfigured for feeder overcurrent protection and circuit breaker control in electrical distribution networks, the GE Multilin MIFIIPI11E1RHI00 (MIF II Feeder Protection Relay) provides direct physical/electrical execution for phase and ground current monitoring, trip logic, and autoreclosing functions.

Suffix Breakdown & Model MatrixHardware Specifications

Process Control & Communication Interfaces

The MIF II unit processes phase and ground AC signals through internal precision current transformers to calculate true RMS values for thermal overload, instantaneous overcurrent, and time-delayed overcurrent tripping functions. Channel-to-channel isolation between internal digital signal processing circuits, auxiliary power supply rails, and field current inputs ensures immunity to severe electromagnetic interference. Serial communication via the isolated rear RS-485 interface utilizes Modbus RTU protocol for remote integration with DCS and SCADA networks.

Frequently Asked Questions

Q: How is the front RS-232 port used during commissioning and maintenance?

A: The front panel RS-232 port provides galvanic isolation for direct point-to-point connection with a PC running EnerVista M II setup software. It allows real-time telemetry monitoring, fault wave retrieval, and field firmware flashing.

Q: Can setting groups be switched remotely during grid reconfiguration?

A: Yes, the relay supports two distinct setting groups that can be toggled locally via the keypad or remotely via digital input status and Modbus RTU communication commands.

Field Installation Guidelines

• Mechanical Installation: Mount the relay flush into a cut-out panel using the standard mounting brackets. Ensure adequate ventilation clearance around the top and bottom chassis heatsink channels.
• Grounding Connection: Connect the rear chassis grounding stud directly to the main station earth grid using a short, low-impedance braided copper strap (minimum 4 mm sq).
• CT Wiring Isolation: Wire secondary current transformer leads to shorting terminal blocks before connecting to the relay CT inputs. Maintain tight screw torque settings to prevent open-circuit CT hazards.
• Serial Shielding: Use twisted-pair shielded cable for the rear RS-485 bus. Ground the cable shield at a single point at the master station end to avoid ground loop circulating currents.