745-W2-P5-G5-HI-A-E 745 GE Multilin Transformer Protection Relays

GE Multilin 745-W2-P5-G5-HI-A-E Transformer Protection System

Configured for two-winding transformer protection in power distribution networks, the GE Multilin 745-W2-P5-G5-HI-A-E (745 Transformer Protection System) provides direct physical/electrical execution. The relay evaluates secondary phase currents and residual ground currents, executing dual-slope percent differential trip equations, restricted ground fault logic, and harmonic restraint algorithm processing to isolate primary grid faults.

Hardware Specifications

Backplane Bus Communication Velocity & Deterministic Logic Execution

The system executes high-speed current transformer signal sampling across dedicated analog conditioning channels, passing digitized values across internal bus backplanes to maintain protection trip calculations without phase lag. Microprocessor execution pipelines evaluate 2nd and 5th harmonic content to block differential tripping during transformer magnetizing inrush and overexcitation conditions. Firmware flash compatibility ensures synchronized register mapping across internal memory banks, enabling high-density data logging, event recorder logging, and oscillography telemetry polling without consuming main protection CPU processing capacity.

Frequently Asked Questions

Q: How does the 745-W2-P5-G5-HI-A-E prevent false differential tripping during transformer energization?

A: The relay uses microprocessor-based 2nd harmonic restraint algorithms to detect magnetizing inrush current and temporarily inhibit differential trip contact output state changes.

Q: What primary control power supply ranges are supported on the HI voltage model?

A: The HI control power supply board accepts an input range of 90-300 VDC or 70-265 VAC at 48-62 Hz.

Q: What grounding procedure must be executed prior to applying primary AC current inputs?

A: The rear chassis copper ground lug must connect directly to the substation earth bus via a low-impedance copper conductor before terminating current transformer secondary connections.

Field Installation Guidelines

1. Isolate high-voltage power lines and verify complete primary transformer de-energization using verified potential indicators prior to installing hardware.
2. Short-circuit all CT secondary leads at the panel test switch block before attaching wiring harnesses to the relay backplane terminal blocks.
3. Secure the relay frame into the panel cutout using standard mounting hardware, ensuring solid metal-to-metal contact to establish local cabinet frame bonding.
4. Route ground conductors directly from the chassis grounding stud to the main panel earth rail, maintaining minimal lead length to reduce RF ground loop impedance.
5. Connect control power wiring, verify input voltage limits with a digital multimeter, and energize the relay to complete hardware self-test diagnostic routines before opening CT shorting links.