Types of Corona Discharge Static Removal Devices

Among the various Types of Static Removal Devices available, corona discharge static removal devices are the most commonly used.
For static removal devices, there are also various types available based on the method of voltage application to the electrode needles. Examples are explained below.

DC System

A system that continuously applies either + or - DC voltage to the electrode needles.

Advantages
Fast static removal
Disadvantages
Can only remove static for one polarity. Satisfactory ion balance.

AC System

A system that continuously applies AC voltage to the electrode needles.
Because it boosts commercial power sources, the ± ion production cycle is 50 or 60 Hz.

Advantages
Because it alternately produces + and - ions, it has a good ion balance.
Disadvantages
Produces a low amount of ions and static removal is slow. Because the ion production cycle often recombines generated ions quickly, long distance mounting is not possible.

High-frequency Wave AC System

A system that uses a piezo element to boost the AC voltage ±2 kV and applies that to the electrode needles at high-frequency.

Advantages
Good ion balance
Disadvantages
Because the voltage values of the piezo elements are low and therefore the amount of ions are low, static removal is slow. Dirt or abrasions on the electrode needles will cause it to quickly become unable to produce ions. Because the ion production cycle often recombines generated ions quickly, long distance mounting is not possible.

Pulse DC System

DC voltage is alternately applied to a + and ? electrode. The + and ? electrodes are generally spaced evenly throughout the static eliminator.

Advantages
Produces a large amount of ions and static removal is fast.
Disadvantages
When using bar type static removal devices, ions in the longitudinal direction will have poor ion balance. Dirt or abrasions on the electrode needles will largely affect the speed of static removal and ion balance.

Pulse AC System

Alternately switches between + and - DC voltage to each single electrode needle.

Advantages
Produces a large amount of ions and static removal is fast. Because it alternately produces + and - ions, it has a good ion balance.
Disadvantages
None

Here follows a collection of features, separated by voltage application system.
Below is a chart comparing the different voltage applications methods discussed above.

Item		DC	Pulse DC	AC	High-frequency Wave AC	Pulse AC
Discharge Frequency		Stationary/Continuous	Pulse 0.1 to 60 Hz	50/60Hz	up to 70 KHz	Pulse 0.1 to 60 Hz
Static removal speed	Short distance	Good	Good	Good	Very Good	Very Good
Static removal speed	Long distance	Good	Very Good	Satisfactory	Satisfactory	Very Good
Ion balance	Short distance	N/A	Satisfactory	Very Good	Very Good	Very Good
Ion balance	Long distance	Good	Good	Good	Good	Very Good