Advanced Marine Electrics and Electronics Troubleshooting A Manual for Boatowners and Marine Technicians

75

Unfortunately, some of the electronic equip-
ment routinely installed on boats can deliver less
than satisfactory performance when powered by
distorted AC sine waves. For example:

• flat-screen televisions—may display
  diagonal lines


• some audio systems—may generate
  annoying background noise


• regular TV screens—may develop an
  audible “hum” and display diagonal lines


• some computer systems, especially sys-
  tems using a UPS (uninterruptible power
  supply)—may work but run too hot; may
  try to turn on and off; or may not work at
  all (note that all the laptops I’ve tried
  work fine with an inverter; some desktops
  may be affected)

analyzing harmonic distortion

printer or PC connection

line or battery power

hard keys

soft keys

rotary selector

test leads

The Fluke 867B graphical multimeter is a full-feature multimeter and oscillo-

scope. It also has the ability to log data over time, and upload it to a PC

for further analysis, something we’ll address in Chapter 8.

A classic symptom of a faulty waveform is

a piece of gear that functions perfectly when

run from the shore-power supply, but acts up

when run from an inverter or generator.

The good news is that with an oscilloscope

you can see and analyze the AC waveform to

detect harmonic distortion (see below).

AC Loads

Let’s look again at the part of the power factor

definition in Chapter 6 that stated “a unity

power factor (1.0) indicates that the current is

in phase with the voltage.” To understand

this, we need to look at some additional defi-

nitions and take a closer look at what happens

in an AC circuit depending upon AC load

characteristics.