Configured for high-speed current transformer signal evaluation in 125 to 250 VDC or 120 to 240 VAC power distribution networks, the GE Multilin 345-E-P1-G1-H-E-M-N-N-3E-D-N (345 Transformer Protection Relay) provides direct physical/electrical execution. This drawout unit monitors primary and secondary transformer windings, processing protective functions including differential protection (87T), instant and time overcurrent element calculations (50/51), and thermal replica overload modeling (49P). The hardware architecture routes raw analog input streams from current transformers into solid-state digital processing engines while hosting local English interface elements and serialized rear RS485 communication loops.

Suffix Breakdown & Model Matrix

Hardware Specifications

• Note: Saved preferences applied — data presented in list format instead of standard tables.
• Model: 345-E-P1-G1-H-E-M-N-N-3E-D-N
• Brand: GE Multilin
• Origin: Canada
• Weight: 3.9 kg (8.6 lbs)
• Dimensions: Standard 345 Drawout Case Architecture (3U/4U Rack Height Profile)
• Operating Temp: -40 deg C to +60 deg C
• Power Consumption: 125 to 250 VDC / 120 to 240 VAC Nominal Range (15 W typical)
• Enclosure Style: Drawout Chassis Design with internal CT Shorting Switches
• Local Interface: English Display Front Panel with Fixed Diagnostic Status LEDs
• Serial Protocols: Modbus RTU, DNP 3.0, IEC 60870-5-103 over RS485 / Front USB
• Protection Functions: 87T, 87T-50, 51P, 51N, 51G, 50P, 50G, 50N, 49P, 46, 86

Backplane Bus Communication Velocity & Network Features

The GE Multilin 345 internal processing pipeline handles high-speed analog-to-digital conversions on phase and ground current channels to maintain deterministic trip decision latency. Firmware execution drives backplane bus data exchange across internal I/O modules with high temporal accuracy, preventing internal bus saturation during high-magnitude fault conditions. Serial communication paths via the front USB and rear RS485 interface support Modbus RTU, DNP 3.0, and IEC 60870-5-103 protocols without altering the core protection engine execution priority. Backplane bus timing routines enforce firmware flash compatibility checks during boot cycles, protecting hardware registers from corrupt parameter uploads.

Frequently Asked Questions

Q: What safety mechanism prevents open CT circuits when removing the 345 drawout unit?

A: The drawout chassis incorporates automatic internal CT shorting mechanisms. When the inner relay unit is withdrawn from the outer case, the current transformer secondary terminals automatically short-circuit before physical contact pin disengagement occurs.

Q: What are the input voltage tolerances for the 'H' power supply option?

A: The high-voltage power supply accepts continuous operating inputs from 125 to 250 VDC or 120 to 240 VAC at standard 50/60 Hz frequencies, providing ride-through capability during short-term station supply voltage dips.

Field Installation Guidelines

1. Ensure the drawout case grounding terminal connects directly to the main station earth ground bus using braided copper strap rated for low impedance at high frequencies.
2. Verify all current transformer secondary circuits maintain correct polarity marking (H1/X1 alignment) prior to landing wire terminations on the rear screw blocks.
3. Keep RS485 communication cables segregated from high-voltage AC power wiring and terminate shielded twisted-pair runs with a 120 ohm resistor at each physical end node.
4. Mount the drawout case in vertical cutouts, verifying panel cutout dimensions allow adequate clearance for drawout handle swing and rear cable strain relief.