For two AC power systems to be interconnected (paralleled), they must be synchronized. This means they must be operating at the same voltage, the same frequency, and the same phase angle. Only when all three parameters match is it safe to connect the two systems. Paralleling two unsynchronized AC systems will cause a sudden current surge and mechanical stress on rotating equipment. (more...)

Frequency is an important parameter for an ac waveform. The frequency, in Hertz, is defined as the number of cycles per second. It can also be expressed as 1/T, where T is the time for one cycle. One period is the duration of one complete cycle, in seconds. (more...)

Most of us are familiar with Bluetooth as the connection from a cell phone to wireless earbuds or a remote speaker. This low-power communication protocol is simple to set up and use. It operates in the globally unlicensed industrial, scientific and medical (ISM) band from 2.40-2.48 GHz. (more...)

Current loops are a popular method for monitoring equipment and processes in industrial environments. Some of their advantages were discussed in an earlier posting. Additional advantages of the 4-20mA loop are:
– easy detection of an open loop, since the signal zero is represented by 4mA.
– the offset zero allows use of loop-powered devices that don’t require a separate power connection. (more...)

In residential applications, ground fault sensing is used to protect a building’s occupants from electric shock. Everyone is familiar with the ground fault interrupter (GFI), incorporated into a duplex outlet, that quickly opens the circuit when a fault is detected. The National Electric Code mandates their use in kitchens, bathrooms and other wet locations. (more...)