Protecting data loggers from electrical discharge (ESD)
A discharge of static electricity may cause a running data logger to stop recording. Precautions should be taken to prevent this while handling the data logger. Discharges may occur in the following situations when there is a charge difference between the data logger and a cable being connected to it or when a person touches an exposed jack.
Precautions to take:
- Equalize the charge between yourself and the data logger before contact. Charge build-up often occurs from walking across a carpet, especially when the humidity is low. Wool, nylon, or polyester clothing increases the charge build-up. Touching a grounded metal object such as a water pipe will dissipate the charge and prevent sparking. When plugging in a cable, handle the plug by the insulated part to reduce charge transfer to the data logger. Do not touch the exposed metal connector shell of the data logger. When using external voltage or current cables, connect the cable to the sensor circuit first before plugging into the data logger.
- On outdoor/industrial data loggers, minimize contact with the board when installing cables. (When outdoors, shoe charge build-up is probably less of a problem, but touching the ground first is a good idea.)
- When changing the battery, ground yourself before opening the data logger and maintain contact with the board during the whole process.
- Keep in mind that static discharge may not appear right away; it could affect the data logger anytime during deployment.
- Be careful when transporting data loggers. When data loggers are launched and transported in bags (especially plastic and nylon), a static electrical charge can be generated and discharged to a data logger. To avoid this, use anti-static bags to transport the data loggers and prevent the introduction of static to the data loggers.
Although we do not have the facilities for testing all environments where static electricity can interfere with data logger operation, feedback from customers has assisted us in developing the following list of potential issues:
- X-Ray machine
- Exposure to an extremely strong magnetic field / overhead power lines
- Electrical/lightning storms
It is always important to check the status of the LED on the data logger to verify operation and to have the equipment and software available to relaunch the data loggers if necessary.