# SEL-387 Current Differential & Overcurrent Relay

> transformer-protection - Transformer differential (up to 4 restraint inputs), restricted earth fault, thermal overload and breaker failure protection for utility substations

**Voltformer canonical:** https://voltformer.com/product/sel-387-current-differential-overcurrent-relay - markdown version: https://voltformer.com/product/sel-387-current-differential-overcurrent-relay.md

## Overview

- **Brand:** SEL
- **Product family:** SEL-300 Series
- **Application:** Transformer differential (up to 4 restraint inputs), restricted earth fault, thermal overload and breaker failure protection for utility substations
- **Product type:** transformer-protection

## Protection & Control Functions

- **ANSI Functions:** 87T, REF/87N, 49, 50/51, 50N/51N, 50BF
- **Transformer Windings:** 2, 3, 4
- **Supports Transformer:** Yes
- **Supports Feeder:** No
- **Supports Breaker Control:** Yes
- **Arc Flash Protection:** No

## Digital Integration & Protocols

- **IEC 61850 Edition:** Ed1
- **GOOSE:** Yes
- **Sampled Values (SV):** No
- **Redundancy (PRP/HSR):** No / Optional
- **Protocols:** DNP3, Modbus, SEL Fast Meter, Mirrored Bits
- **Engineering Software:** acSELerator QuickSet

## Electrical Interface

- **Frequency:** 50/60 Hz
- **Nominal Current:** 1 A / 5 A
- **Auxiliary Supply:** 110-250 Vdc / 110-240 Vac
- **Operating Temperature:** -40 to +85 °C

## Standards

- IEC 60255
- IEEE C37.90

## Sources

- https://selinc.com/products/387/

- **Source scope:** manufacturer-family
- **Last reviewed:** 2026-09-13

Manufacturer portfolio/family source. Confirm the exact order code, guaranteed ratings and project-specific options against the current OEM datasheet before procurement or an SLD study.

Technical ratings are configuration-dependent where stated by the manufacturer. Request project-specific verification before procurement.