The relationship between static electricity and humidity
Static electricity changes depending on humidity. We will explain in an easy-to-understand manner using graphs and formulas how it changes specifically.
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The higher the absolute humidity and relative humidity, the faster static electricity will decrease
When examining the relationship between static electricity and humidity, it is found that the higher the absolute humidity and the higher the relative humidity, the faster static electricity decreases.
This is thought to be because high humidity increases the electrical conductivity of the surface of a material, accelerating the rate at which charges leak.
The higher the absolute humidity, the faster static electricity will decrease.
The vertical axis (y) of the graph below is the scattering time (time constant), and the horizontal axis is the absolute humidity. The scattering time can be considered as the time it takes for static electricity to decrease.
The higher the absolute humidity, the less likely it is that static electricity will build up. The degree of difficulty in accumulating static electricity in relation to the degree of humidity is extremely large.
- *"Absolute humidity": the weight of water vapor contained in 1m³ of air
- *The graph above shows the results of measuring the potential by fixing a potential probe 5 cm from the surface of charged Japanese paper.
Even at the same absolute humidity, static electricity disappears in a short time if the temperature is lowered.
It is known that γ (scattering time) = R (electrical resistance) × C (capacitance).
In this case, R (electrical resistance) decreases exponentially as the relative humidity increases, as shown in the graph below.
This means that the higher the relative humidity, the greater the decrease in scattering time.
- * "Relative humidity" is the ratio of the amount of water vapor contained in a unit volume of air at a certain temperature to the amount of saturated water vapor.
Relationship between electrical resistance of Japanese paper and discharge time
| R:電気抵抗(Ω) | Discharge time (s) |
|---|---|
| 1011 | 50 |
| 1010 | 5 |
| 109 | 0.5 |
*Static electricity discharge time calculated when electrical resistance changes according to graph 2 under the conditions of graph 1.
Effective humidification measures dramatically reduce static electricity
The key to preventing static electricity is to prevent it from occurring in the first place. Apiste 's PAU series precision air conditioner (TCU/ECU) offer environment that is less susceptible to static electricity.
- Prevents contamination when laminating films, etc.
I want to prevent - Ionizers alone cannot completely eliminate static electricity
- I want to take measures against electrostatic discharge (ESD).
