Provided by the ESD Association

Specifying Electrostatic Measurement Tools

With many instruments available for program evaluation, how does one choose effectively?

Q: There are many instruments available for making electrostatic measurements. What types of equipment do I need to audit and evaluate my program?

A: Because most material and procedure evaluations involve charge or voltage generation, resistance or resistivity, or ground connections, the typical minimum instrumentation requirements include an electrostatic field meter, a charge plate monitor, a wide-range resistance meter, a ground/circuit tester, and the appropriate electrodes and accessories.

Because resistance and resistivity are key parameters in evaluating many ESD control materials, a wide-range resistance meter is one of the most critical instruments. It should be capable of applying both 10 V and 100 V to the materials being tested. The meter must also be capable of measuring resistance ranges of 10³ to 10¹² , depending on the resistance range of the materials you typically use.

Many standard test methods specify test instruments with open circuit voltages (OCVs). The actual applied voltage of these instruments may vary with the resistance of the material depending upon the short-circuit current of the instrument. Be sure you know the actual applied voltage of the instrument.

For measuring electrostatic charge or voltage, you will need a handheld electrostatic field meter or a charge plate monitor. Many field meters simply measure the gross level of electrostatic charge, and are used as general indicators of the presence of a charge and its approximate level. A charge plate monitor can be attached to some field meters for greater precision in facility measurements or connected to a voltmeter for laboratory evaluation.

Finally you'll need a simple ground/circuit tester. With this device you can measure the continuity of your ESD grounds and check the impedance and neutral-to-ground shorts.

Your specific needs are determined by what you are trying to measure, the required precision, and the sophistication of your program. Instrumentation requirements for laboratory evaluation of materials are usually different from those for auditing or monitoring your program on the factory floor. While some meters are designed for very precise measurements and typically would be used for laboratory evaluations, others are less precise, usually designed for portability and implemented for auditing and monitoring.

In selecting your instrumentation, remember this: you want the right tool for the job.

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