GE Multilin 345 | 345-E-P1-G1-H-E-S-N-N-1E-D-N Transformer Protection System

The GE Multilin 345 is a high-speed, microprocessor-based relay designed for the protection and management of small-to-medium sized power transformers. Part of the SR (Standard Relay) family, the 345 provides comprehensive protection against internal and external faults, ensuring the longevity of expensive transformer assets. This specific configuration (345-E-P1-G1-H-E-S-N-N-1E-D-N) includes advanced features such as differential protection, restricted earth fault (REF), and integrated communication protocols for modern smart grid environments.

Part Number Breakdown (Configuration)

The alphanumeric string defines the specific hardware and software features of the relay:

  • 345: Base Model (Transformer Protection System)

  • E: English Language Display

  • P1: 1A Phase Current Input

  • G1: 1A Ground Current Input

  • H: High Voltage Control Power (88–300 VDC / 70–265 VAC)

  • E: Ethernet Communication (10Base-T)

  • S: Standard Functional Package (includes 87T Differential)

  • 1E: Enhanced Front Panel (with display and keypad)

  • D: Conformal Coating (for protection against moisture/corrosion)

GE MULTILIN 345 345-E-P1-G1-H-E-S-N-N-1E-D-N TRANSFORMER PROTECTION

Product Specifications

  • Protection Functions: 87T (Transformer Differential), 50/51 (Instantaneous/Time Overcurrent), 50G/51G (Ground Overcurrent), 87N (Restricted Earth Fault), 49 (Thermal Overload), 2nd Harmonic Inrush Restraint.

  • Monitoring: High-accuracy metering (I, V, P, Q, S, Hz), Percent Differential/Restraint currents, Transformer life usage/health monitoring.

  • Communications: Modbus RTU, Modbus TCP, DNP 3.0, and IEC 61850 (optional).

  • Data Logging: 1024 Event Records, 32-sample Oscillography (waveform capture).

  • Display: 20-character x 4-line backlit LCD.

  • Dimensions: 1/2 size 19-inch rack mount (4U height).

  • Environment: Conformal coating included for enhanced chemical and moisture resistance.

Application Fields

The Multilin 345 is primarily used in Substation Automation, Industrial Power Plants, and Renewable Energy Sites. It is specifically designed to protect two-winding transformers against short circuits, winding-to-winding faults, and overloads. By utilizing 2nd harmonic restraint logic, it can distinguish between a dangerous internal fault and a normal “inrush” current that occurs when a transformer is first energized, preventing nuisance trips.

Product Instructions

  1. Mounting: Install the relay in a standard switchgear panel or relay rack. Because this model includes the -D (Conformal Coating) option, it is better suited for environments with high humidity or atmospheric contaminants.

  2. CT Ratio Configuration: It is critical to program the correct Current Transformer (CT) ratios into the relay settings. The 345 uses these ratios to perform internal vector compensation and magnitude balancing, which is necessary for the differential protection (87T) to function without tripping under normal load.

  3. Wiring: Connect the phase CTs from both the High Voltage (HV) and Low Voltage (LV) sides of the transformer to the relay’s rear terminal blocks. Ensure proper polarity (dot convention) to maintain the integrity of the differential zone.

  4. Software Setup: Use the EnerVista 3 Series Setup software for configuration. Download the existing settings from the relay before making changes to ensure a baseline configuration is saved.

FAQ: Common Questions and Answers

Q: What is the purpose of the 87N (Restricted Earth Fault) function? A: REF protection provides very sensitive detection for ground faults near the star-point (neutral) of the transformer winding, where standard differential protection might not be sensitive enough to trigger.

Q: Can I use this relay for a three-winding transformer? A: No, the Multilin 345 is designed for two-winding transformer applications. For three-winding transformers, the Multilin 745 or 845 series would be the appropriate choice.

Q: Does the “H” power supply option support DC battery banks? A: Yes, the “H” option is a universal power supply that operates on common substation battery voltages, including 110V DC and 220V DC.

For high-resolution technical data and availability regarding the GE Multilin 345, please visit our technical portal.

Recommended Similar Models

  • GE Multilin 745 (High-end Transformer Protection)

  • GE Multilin 845 (Next-Gen Transformer Protection System)

  • GE Multilin 350 (Feeder Protection System)

  • GE Multilin SR469 (Motor Management Relay)

  • GE Multilin SR489 (Generator Management Relay)

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