Model Interpretation

SR750: 750 series feeder management relay

P5: 5 A phase CT secondary input

G1: 1 A ground/zero‑sequence CT input

S1: Standard sensitivity for ground fault protection

HI: High‑impedance control power (70–265 VAC / 88–300 VDC, 48–62 Hz)

A20: 8 analog outputs (4–20 mA)

Technical Parameters

Input & Power

Phase CT Input: 5 A (standard)

Ground/Zero‑Sequence CT Input: 1 A

VT Input: 60–120 V phase‑neutral

Control Power: 70–265 VAC / 88–300 VDC, 48–62 Hz

Power Consumption: ≤15 VA typical

Protection Functions

Overcurrent: Phase/ground, IEC/ANSI inverse/time‑definite, 0.1–20×In

Ground Fault: Sensitive earth fault (1 A input), restricted earth fault (REF)

Voltage/Frequency: Over/undervoltage, over/underfrequency, loss of voltage

Directional Protection: Directional overcurrent/ground fault (for loop/grid feeders)

Breaker Failure: Local/remote breaker failure protection

Trip Time: ≤15 ms (instantaneous overcurrent); ≤30 ms (ground fault)

I/O & Interfaces

Analog Outputs: 8 × 4–20 mA, isolated, 600 Ω max burden

Digital Inputs: 16 opto‑isolated (dry/wet, ≤1 ms response)

Relay Outputs: 8 Form C (5 A / 250 VAC); 3 dedicated (trip, close, self‑test) + 5 configurable

Communication: RS‑232 (front), RS‑485 (Modbus RTU/DNP3), optional Ethernet (IEC 61850)

Display & User Interface

Display: 40‑character backlit LCD (enhanced)

Indicators: 12 LED (RUN, TRIP, ALARM, FAULT, BREAKER STATUS)

Keypad: Numeric/navigation for local programming; password protection

Mechanical & Environmental

Dimensions: 228.6 mm H × 177.8 mm W × 180.9 mm D (9”×7”×7.125”)

Mounting: Panel mount (19” rack compatible), drawout chassis

Enclosure: Flame‑retardant plastic; IP50 (front), IP20 (overall)

Operating Temp: -40°C to +60°C

Humidity: 5–95% non‑condensing

Certifications: UL, CE, CSA, IEC 60255

Metering & Diagnostics

Metering: 3‑phase current/voltage, power, energy, frequency, PF, demand (0.2% accuracy)

Diagnostics: Event log (1024 events), fault recorder (256‑cycle oscillography)

Breaker Monitoring: Trip count, contact wear, coil current monitoring

Core Functions

Comprehensive Feeder Protection: Fast, selective protection for phase/ground faults in distribution feeders.

Sensitive Ground Fault Detection: 1 A ground input detects high‑impedance faults to reduce unplanned outages.

Wide‑Range HI Power: Compatible with 70–265 VAC / 88–300 VDC for flexible substation integration。

8 Analog Outputs: Isolated 4–20 mA outputs for direct connection to SCADA/DCS。

Advanced Fault Diagnostics: Oscillography and event logs enable root‑cause analysis。

Applications

Power Utilities: Distribution substations, overhead/underground feeders, loop networks

Industrial Plants: Petrochemical, metallurgy, mining, water treatment (MV feeders)

Renewables: Wind/solar farm collector feeders, grid interconnection points

Commercial Buildings: Large‑scale MV distribution systems

Usage & Maintenance

Installation: Panel‑mount; wire CT/VT, HI control power, and communications.

Programming: Use front keypad or EnerVista 750 software via RS‑232/Ethernet.

Configuration: Set CT/VT ratios, protection curves, and I/O mapping.

Maintenance: Inspect terminals annually; update firmware; verify settings after system changes.