Effect of harmonics from SCR drive on other components

How much harmonic depends on your scr equipment quality.

this will interference on computer, chrger etc electronic facilities. some times, electronic ballast of tube and hlidelamjpe are also interferenced it.

although now they are not connect to a same transformer, but the harmonic wave can go throgh electric net.

so the best bet is adding a filter, shield and good chases to reduce the interference.

"The increased use of computers and solid state electronics in the modern workplace has been accompanied by an increase in the presence of destructive harmonics within electrical distribution systems. Symptoms of destructive harmonics include, but are not limited to: nuisance tripping of circuit breakers, blown fuses, failed motors, and overheated transformer windings and neutral conductors. Since harmonics are often accompanied by a temperature rise, thermography can be used to detect evidence of their presence. This paper will discuss the causes, effects, and symptoms of harmonics as well as techniques for dealing with harmonics"

"Sites that utilize electronic drives and power transmission systems with six and twelve pulse SCR's commonly have similar problems. These types of SCR drive systems also cause distorted currents which in turn cause overheating on cabling and transformer windings"

Source:

www.irinfo.org/Articles/02_01_2007_handlin.html

There is some very good info in that paper!

I work in a data center, we had a terrible time with harmonics from EMF.

The company finally had to have the intire raised floor area grounded at the SRGs and to the main building ground.

They also added electrical protection from lightening as they were doing this.

The bleeding of electrical harmonics and EMF was so bad, you could change a defective fluorescent bulb, as I touched the bulb, the bleeding surge would cause the nearest emergency door alarm to ring.

They have now cut back on the problems of blade servers and cabinet power supplies from frying. I hope this helps.

That problem is often seen in office buildings. It is typically caused by bad wiring of the neutral conductor. Incompetent electricians do not keep the line and the corresponding neutral together from the breaker box up to the load. This usually happens during wiring modifications where branches are pulled from existing wiring almost randomly. They often tap on the first neutral they find even if it doesn't corresponds to the line they are using. This created large inductive loops in the electrical supply. Inductive loops are antennas, and you know what they do. Also, the inductive loops produce unwanted voltage drops which can affect the loads.

Adding grounds can minimize this effect but is it the wrong way to do it as it encourage the ground wires to become neutral conductors conducting the imbalanced current between the line and the neutral(s) wires.

If you really want to solve this problem, re-wire the area properly with three conductors cables (L,N,G) and minimize branching.