RV4146

The RV4146 has the following features including Built-in grounded neutral oscillator;Direct interface to SCR;1 mA quiescent current;Precision sense amplifier;Adjustable time delay;Minimum external components;Meets UL 943 requirements;For use with 110V or 220V systems;Available in 8 pin DIP or SOIC package;Differential circuitry for noise immunity;Trip time dependent on fault magnitude.

The RV4146 is a low power controller for AC receptacle ground fault circuit interrupters. These devices detect hazardous current paths to ground and ground to neutral faults. The circuit interrupter then disconnects the load from the line before a harmful or lethal shock occurs.Internally, the RV4146 contains an oscillator, shunt regulator, precision sense amplifier, current reference time delay circuit, and SCR driver.Two sense transformers, SCR, solenoid, four diodes, three resistors and four capacitors complete the design of the basic circuit interrupter. The simple layout and minimum component count insure ease of application and long term reliability.Features not found in other GFCI controllers include a low offset voltage sense amplifier, eliminating the need for a coupling capacitor between the sense transformer and sense amplifier, and an internal oscillator to eliminate the sensitivities of the dormant
oscillator.

The RV4146 senses current faults independent of its phase relative to the line voltage. The gate of the SCR is driven during both cycles of the line voltage. Noise immunity is maximized on the RVxxxx, but the use of differential circuitry with 3 times the discharge current as charge, and low output impedance on the SCR driver.The sense and ground/neutral transformer cores are usually fabricated using high permeability laminated steel rings. Their single turn primary is created by passing the line and neutral wires through the center of its core. The secondary is usually from 200 to 1500 turns.This formula assumes an ideal sense transformer is used. The calculated value of RSET may have to be changed up to 30% to when using a non-ideal transformer.