Voltage Measurement

• What Is Voltage?
• How to Measure Voltage
• Effect of Inter-channel Insulation
• Triggers

• How to Select a Data Logger for Voltage Measurement
• Key Points in Selecting the Sampling Cycle
• Thinking about Resolution and Accuracy

• Applications and Examples of Analog (Current/Voltage) Measurement

Electrical voltage is referred to as a difference in the electric potential or electromotive force between two points. It’s a fundamental concept in electricity, and for those who aren’t familiar with the field, the voltage can be thought of as a force that drives the flow of electrons—the electric current—from the point of higher electric potential toward the point of lower potential or ground.

Think of voltage as a pressure in the water pipe; just as water pressure pushes water through a pipe, voltage pushes the electric current through an electrical circuit. In simplest terms, voltage is a measure of potential energy per unit charge between two points within an electric field.

The voltage causes current to flow, and the higher the voltage, the more potential energy can be pushed through the circuit. Here’s an example. Currents above 30 mA are potentially lethal for humans, and 3 A (3,000 mA) at 110 V is considered exceptionally dangerous.

However, 3,000 mA at 5 V isn’t nearly as dangerous because 5 V isn’t typically enough to overcome the natural electrical resistance of the human body and is less likely to cause damage or fatality.

Please note that we still highly advise against touching any electrical or electronic circuits with your bare hands, regardless of current and voltage levels. With that said, for measuring voltage, it’s important to differentiate between direct and alternating voltage.

Voltage measurement is typically done with a voltmeter, though multimeters are much more common nowadays. When measuring DC voltage between two points, connect your multimeter or measuring device’s probes to the appropriate points.

The device will measure a difference in potential between two points or measure voltage levels relative to the reference point. Assuming you’re measuring 5 V, the measuring device, such as a data logger or data acquisition system, will either output 5 V or -5 V. If you get a reading of -5 V, that means that the polarity of your probes doesn’t correspond to the polarity of the points you’re measuring.

Switching the probe placement solves this problem and indicates which point is 0 V (ground) and which carries a charge, in this case, 5 V.