Managing the Testing Process: Practical Tools and Techniques for Managing Hardware and Software Testing

A.3. Electrical Testing

This is one type of testing that, unlike almost all software tests, poses an actual risk of physical danger to the test and the system under test. Even a system that is not powered up can have potentially deadly electrical charges stored in capacitors or batteries. Only qualified professionals should perform any type of test, but in running electrical tests, this fact is especially critical.

Electrical tests come in many flavors. One type of electrical test is making sure the signal waveforms are correct on running systems. This type of testing, called "signal quality" testing, also includes checking for inappropriate voltages or potential current flows in various places, especially externally accessible ports. With systems supplying power to external devices such as USB ports and peripherals, the possibility exists for dangerous (to the hardware) situations.

Another type of electrical testing is checking to see how the system responds to various types of power conditions. In the United States, Canada, and Taiwan, 120 volts and 60 hertz are the nominal voltage and frequency coming out of the wall, but in Europe and much of Asia, 240 volts and 50 hertz are the norm. Temporary losses in voltage ("sags" or "brownouts") happen in various locations around the world, including even the high-tech state of California in 2001. How will voltage spikes affect your system? The best software in the world doesn't do any good if the host system crashes every 15 minutes ...