The thyristor dimmer electromagnetism interference suppression ability is depending on its choke's comprehensive electromagnetism characteristic. The CODE PD series dimmers exhibit good EMC performance with their choke outstanding material quality and the fine craft.

The thyristor dimmer use "phaser chopper" the way work, its output voltage waveform profile is extremely steep also has "overshoot", therefore in dimming process to cause the filament vibration noise.

At the same time, the steep rise profile also produces the abundant higher harmonics, these frequency spectrum very wide chirp waves induct can have the electromagnetism interference the electrical network or the radiation to the space to other equipment, the high power dimmer is very serious especially.

In order to improve above situations, usually inserts the "choke"; into the circuit. The thyristor dimmer early product generally adopts the cheapness choke which made of the flaky material.

This type of choke can act on the leading edge of the output voltage with approximately 200uS-400uS delay, has suppressed a mass of higher harmonics component, causes the output voltage noise wave band width drop from more than ten MHz while no choke to more than ten kHz, has weakened to other equipment electromagnetism interferences and the lamp filament vibration noise.

However, this type of choke hysteresis coefficient big, magnetostriction coefficient big, eddy current loss big thus causes the filter efficiency lowly, and the electromagnetism noise is big, working temperature rise higher. This type of choke is being gradually eliminated.

The CODE new PD series dimmers use the choke which made of the powder alloy material. This kind of material has small hysteresis coefficient, small magnetostriction coefficient, small eddy current loss, strong anti-saturation capacity and so on characteristic, thus the transient response is quick, the filter efficiency is high, the electromagnetism noise is small, and the working temperature rise is low.

Actual test indicated that, this type of choke can act on the leading edge of the output voltage with 400uS(10A)~700uS(30A) slowly delay, also the voltage rise very "smooth", causes the output noise wave band width drop from more than ten kHz to 6kHz (10A) or 3kHz (30A), has suppressed the dimmer disturb to other equipments and to electrical network effectively.

At the same time, the electromagnetism noise, the working temperature rise, the lamp filament vibration noise and so on greatly for reduces compared to the early choke.

The powder alloy material choke application greatly enhanced CODE the PD series dimmer whole electromagnetic compatibility performance and the comprehensive technical specification.