When it comes to measuring electrical parameters, there are two essential tools to consider: clamp meters and multimeters. While they share some similarities, they serve different purposes and offer distinct advantages.
Multimeters, also known as digital multimeters (DMMs), excel at voltage measurements and possess limited current capabilities. They provide high resolution, measuring in millivolts, milliamps, and milliohms. Although their current measurement range typically goes up to 20 amps, attaching a plug-in clamp accessory allows for measurements of higher currents.
On the other hand, clamp meters primarily focus on current measurements and offer limited voltage capabilities. They generally measure to the nearest tenth or hundredth of a unit, which is usually sufficient for most electrical tasks.
Traditionally, electricians used test probes for current measurements, which required breaking the circuit. Clamp meters, however, enable current measurements without interrupting the circuit, providing real-time readings. Furthermore, newer clamp meters employ flexible current probes like Fluke's iFlex®, which can navigate through tightly packed wires or around large conductors. These probes prove useful in various scenarios, such as measuring conveyor speed and motor current simultaneously or troubleshooting voltage fluctuations at a motor drive.
Troubleshooting often necessitates simultaneous voltage and current measurements. While a single meter cannot accomplish this, higher-priced equipment designed for power quality work can handle such tasks. For electricians, a clamp meter serves as a versatile diagnostic tool, whereas industrial troubleshooters benefit from having separate clamp meters and DMMs.
A cost-effective approach for many technicians is to invest in a quality DMM primarily designed for voltage measurements and a separate clamp meter primarily used for current measurements. The specific combination of test equipment depends on the nature of the work and the required measurements. In some cases, using a low-pass filter with a clamp meter can help eliminate electronic interference that might distort readings.
To determine the right meter for your needs, consider the following guidelines:
- Basic meter: If your work mainly involves basic voltage and continuity measurements.
- High-end digital multimeter: If your job entails power quality work and requires high resolution and advanced features not found in clamp meters.
- Basic clamp meter: If you only require basic current measurements, such as ensuring uniform current across three phases.
- Logging clamp meter: If you need to address intermittent breaker trips.
- Multimeter or clamp meter with a detachable display: If you want the convenience of taking remote readings safely without assistance.
- Advanced clamp meter: If you need to accurately measure motor inrush current or if you require a clamp meter with advanced signal processing to measure the output of a variable frequency drive.
Ultimately, the choice between clamp meters and multimeters depends on the specific equipment you work with and the measurements you need to make.