Thursday, 30 April 2015

Measure A Positive Static Charge

Static electricity can make hair stand on end.

Cold, dry days produce conditions ideal for static electricity in the home. Nearly everyone has experienced a quick static discharge while reaching for a doorknob. Thousands of volts are behind these sparks -- enough to damage sensitive electronics. Identifying and safely eliminating static electricity is essential in electronics, manufacturing and aviation. Electrostatic discharges (ESD) can arise from friction between two materials, like film pulled across a roller, shoes on the carpet or even air traveling over an aircraft wing. Identifying the problem is the first step to mitigating or eliminating it.


1. Measure electrostatic potential with an electrostatic voltmeter. These meters have extremely high input impedance to prevent a static discharge through the meter. Their sensors need to be near a potential ESD material, but not in contact with it. The charge is induced in the sensor and applied to a capacitor and a buffer amplifier before measurement. These meters use auto-ranging and automatically display voltage polarity,

2. Measure the electrostatic charge on a small object with a nanocoulomb meter equipped with a Faraday cup. The charge transfers to the cup and the nanocoulomb meter will measure it down to 0.01 nanocoulombs. A Coulomb is the charge necessary to deliver one ampere of current in one second, so a nanocoulomb is one-billionth of that charge. A nanocoulomb meter measures charges far smaller than the electrostatic voltmeter.

3. Use an electrostatic field meter for precise measurements of an ESD field. Sometimes called static meters or static locators, these meters must be placed within a known distance of the surface to be measured. For instance, if the meter is calibrated with a 1-foot square plate charged to 1-kilovolt and the sensor is placed 1 inch away, subsequent measurements must be performed at the same distance.

Tags: nanocoulomb meter, electrostatic voltmeter, Measure electrostatic, static discharge, static electricity, These meters