05-05 2023
What You Need To Know Before Buying A Digital Multimeter
In the field of solar photovoltaics, digital multimeters are the most commonly used tool for troubleshooting, verifying diagnostics, and confirming repairs by solar contractors. With hundreds of options, how do you know which DMM is right for you? First, let’s look at what a digital multimeter is.
A digital multimeter is a test instrument used to measure two or more electrical quantities (mainly voltage, resistance, and continuity). It is the standard diagnostic tool for technicians in the electrical/electronics industry.
The digital multimeter combines the control functions of a single-purpose meter – a voltmeter (for measuring volts), an ammeter (for measuring amperes), and an ohmmeter (for measuring ohms). They usually include some additional specialized features or advanced options. Technicians with special needs, such as those working in the solar industry, can find a model that suits their needs.
DMMs are best for installing and troubleshooting combiner boxes and inverters, for quick voltage readings, and in environments where AC, DC, or phantom voltage is present.
The increase in the frequency and level of transient overvoltages in modern power systems has led to tougher safety standards for electrical measuring equipment. Transients occurring at the power source (mains, feeder, or branch circuit) can trigger a chain of events that could result in serious injury. Test equipment must be designed to protect personnel working in high voltage and high current environments. What you should pay attention to when choosing test equipment:
To determine the correct overvoltage category of an installation (CAT II, CAT III or CAT IV), it is important to always select tools rated for the highest category and choose a voltage rating that meets or exceeds these conditions. Meters with a CAT rating are designed to minimize or reduce the possibility of arc flash inside the meter. Denominations are usually located near the input socket.
Every application that uses a DMM presents a potential safety hazard that must be considered when making electrical measurements. Before using any electrical test equipment, the user manual should always be consulted first for proper operating procedures, precautions and limitations.
There are basically three types of DMMs with varying degrees of CAT rating, safety features, resolution, and accuracy. Below are the details of each option.
Finding the right DMM for the job requires many considerations. Choose carefully to ensure that the tool has a long service life when evaluating solar projects.
Sean Sylvie has been a Fluke Applications Specialist for the past five years. Prior to that, he was a Residential/Commercial HVAC Technician and most recently a Field Service Manager. Sean’s focus is on application awareness and product education.
