Overview
The IES-311 is a microprocessor-based device designed for protection, control, and monitoring of primary equipment in various grounding systems. It offers flexible configuration and high investment security with low operating costs.

Specifications
- Automatic switch over of backup power supply with flexible PLC logic.
- Unique phase selection element for reliable phase determination.
- CB failure protection with dropout time less than 12ms.
- GOOSE function for simple busbar protection and reduced fault clearing time.
- Supports multiple inverse-time characteristic curves in IEC and ANSI standards.
- Phase broken protection using current ratio criterion.
- Single-ended fault location with less than 5% error.
- Up to 10 remote-control outputs for controlling breakers and switches.
- Device restart time is less than 10 seconds.
- RAM supports ECC and parity check for reliability.
- Dual AD real-time sampling for mutual verification and error detection.

Features
- Modular design for software and hardware with flexible configuration.
- Secondary rated current support for 1A & 5A.
- High-capacity relay for direct tripping.
- Dust-proof and moisture-proof chassis with IP54 protection grade.
- Various mounting methods supported.
- Configuration tool for user flexibility and reduced debugging workload.
- Decoupling of software and hardware for rapid diagnosis.
- Multiple time-synchronization methods supported.
- Compliance with IED cyber security standards.
- Large capacity data recording in COMTRADE format.

Protection Functions
- Includes phase overcurrent, directional and non-directional overcurrent, earth fault overcurrent, negative-sequence overcurrent, sensitive earth fault, phase overvoltage, residual overvoltage, negative-sequence overvoltage, positive-sequence overvoltage, phase undervoltage, overfrequency, underfrequency, undercurrent, breaker failure, thermal overload, restricted earth fault, current unbalance, voltage unbalance, and automatic reclosure protections.

User Interfaces
- Friendly HMI interface with LCD and easy-to-use keypad.
- Push buttons for open/close and local/remote control selection.
- Programmable operator push buttons and target LEDs.

Control Functions
- Switchgear control, double point status synthesis, remote/local control mode switch, interlocking logic, direct control, and closing synchronism check.

Communication Functions
- Supports Modbus, DNP3.0, IEC 60870-5-103/104, IEC 61850 ED1/ED2.0/ED2.1, IEC 62439 PRP/HSR, IEEE 802.1w RSTP.
- Up to four 10Base-T/100Base-TX copper ethernet ports and four 100Base-FX optical ethernet ports.
- Two RS-485 serial ports.