Ionisation is one of the best methods of removing charges from insulators and as a result plays an important role in controlling ESD. Remember though: an ioniser is a secondary form of defence and does not eliminate the need for standard ESD control devices such as wrist straps, heel grounders and work surface mats. It is only one element in an effective ESD programme.
Why Use Ionisers?
The video below highlights why Ionisers are important in eliminating ESD charges on a workbench.
What type of Ioniser to choose?
Types of Ionisers
Electrical ionisers generate air ions by a process known as corona discharge. A high voltage is applied to one or more sharp points and quantities of air ions are created. Fans or blowers may be incorporated in the ioniser to assist the movement of the ions and enhance performance.
- AC Ionisers
AC Ionisers use a transformer to multiply the AC power line voltage. AC stands for Alternating Current, which means that the power cycles from positive to negative sixty times per second. The AC ioniser, therefore, produces both positive and negative ions from the same points or emitters. The drawback with this approach is that many ions recombine because the cycle frequency is too fast. For this reason, most AC ionisers rely on fans or blowers to be effective.
- Pulsed DC Ionisers
Pulsed DC ionisers utilise separate power supplies to generate positive and negative voltages and usually each power supply has it’s own dedicated emitters. The power supply alternates between positive and negative, but usually at a lower frequency than AC units. In this way, ion recombination is reduced and performance is increased. Airflow may then be reduced for operator comfort without sacrificing much performance. With pulsed DC, it is important to cycle at least two or three times per second to prevent harmful voltage swings on the object being protected.
- Steady-state DC Ionisers
Steady-state DC ionisers also employ separate power supplies and emitters, but instead of alternating positive and negative, both supplies are on all the time as the name implies. As would be expected, there is some degree of recombination, however, the ion density is still greater because of continuous operation of both supplies. The offset or balance voltage at the output will normally be more consistent than pulse units.
There are also nuclear types of ionisers which are non-electric. They are more frequently used in flammable or explosive environments for applications other than electronics.
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