GE IAC77B User Manual

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GE IAC77B Specifications

General

Brand	GE
Model	IAC77B
Category	Relays
Language	English

Summary

Relay Description and Application

Detailed Relay Description

Explains IAC77/IAC78 relays, their extremely inverse characteristics, components, and case.

Application in Distribution Circuits

Construction and Components

Induction Unit Construction

Details the induction disk construction, wattmetric element, phase-shifting circuit, and moving contact.

Relay Ratings and Specifications

Time Overcurrent Unit Ratings

Presents pickup ranges and available taps (50/60 Hz) for the time overcurrent unit.

Instantaneous Unit Ratings

Provides continuous and one-second ratings for the instantaneous unit, including range selection.

Target Seal-in and Contact Ratings

Servicing and Adjustments

Time Overcurrent Unit Adjustment

Details adjusting the stationary contact brush and ensuring proper contact wipe for the time overcurrent unit.

Pickup and Time Tests

Instantaneous Unit Setting

Explains setting instantaneous unit pickup by adjusting the pole piece, with operational cautions.

Detailed Testing Procedures

Target and Seal-in Unit Tests

Installation Time Overcurrent Unit Tests

Installation Target Unit Tests

Periodic Maintenance and System Tests

Periodic Unit Checks

Recommends periodic checks for Time, Instantaneous, and Target/Seal-in units at 1-2 year intervals.

Contact Cleaning

Unit-Specific Testing and Calibration

Instantaneous Unit Calibration

Details testing instantaneous unit pickup and compensation, checking current against specified limits.

Time Overcurrent Unit Calibration