Why Use a CAT Level III Clamp Meter in a Solar PV Installation?

Globally, solar installations (also known as photovoltaic or PV installations) continue to grow rapidly, driven by the extremely attractive economics of utility-scale solar power generation and efforts to decarbonize the grid. As solar power distribution systems and loads become larger and more complex, the potential for transient overvoltages increases, and its impact on safety becomes more important than ever.

When you're taking measurements on a solar installation, these transients are invisible and largely unavoidable hazards, meaning that your protection depends on the safety margin already built into the tool. This is where the "Measurement Category Safety Level" comes in: it is designed to tell the user what type of electrical installation the measuring device can safely measure.

However, a voltage rating alone doesn't tell you how well a handheld tool is designed to withstand high transient pulses – its category safety rating also needs to be appropriate for the environment you're working in.

Information on the safety level of the overvoltage category

The standards that specify the safety level of the measurement category are all in order to ensure safety. The International Electrotechnical Commission (IEC) has developed safety standards for measuring equipment to ensure that instruments and operators are never the weak link in the system, and if voltage transients occur, they are not a point of failure. Measurement categories are defined as follows.

Why Use a CAT Level III Clamp Meter in a Solar PV Installation?

Distribution systems are classified based on the fact that dangerous high-energy transients (e.g., lightning strikes, switching transients) will attenuate or dampen as they pass through the impedance (AC resistance) of the system. The higher the measurement category, the greater the expected fault current available and the higher the voltage transients – measuring power supplies at less than 1500 V in a CAT III environment and peaking up to 10000 V.

The solar installation is a CAT III environment

IEC 61730-1 defines a photovoltaic module as a permanently wired electrical installation (CAT III) rather than using a point electrical outlet (CAT II).

In addition to performing actual overvoltage transient value testing, the handheld measurement tool needs to have a minimum level of insulation (a combination of solid insulation, clearance, and creepage) between internal components and circuit nodes to comply with the appropriate category safety level. Insulation protects internal circuitry from fire/arc failures and also protects the operator from electric shock. The higher the safety level of the operating voltage and measurement category, the higher the insulation required.

In the measurement category, a higher voltage rating indicates a higher transient withstand rating. For example, a CAT III 1500 V meter can withstand higher energy transients and therefore provides superior protection compared to a CAT III 1000 V meter.

The voltage of the solar installation is constantly rising

The overvoltage CAT III 1500 V system is becoming the new normal in solar energy, providing cost savings and increased efficiency for facility owners. Each inverter can handle more energy, and more panels can be connected in series into longer strings, which reduces the number of wires and inverters required.

To ensure safety and accuracy, measurements in an overvoltage CAT III environment require the use of CAT III safety class tools.

The Fluke 393 FC Solar Clamp Meter is the only CAT III 1500 V/CAT IV 600 V TRMS Clamp Meter that meets the insulation requirements of CAT III environments such as solar installations and measures voltages up to 1500 V dc.

The CAT III 1000 V current clamp has a dielectric test of 8000 V pk/7000 V rms. For CAT III 1500 V, 10000 V pk/9700 V rms.

When choosing a measuring tool for a PV panel, it's worth considering the worst-case scenario of the job. First, choose a meter with a safety rating that fits the highest category you may measure. Then, look for the voltage rating that meets your needs. Choosing the right CAT safety rating tool for your environment can help you and your team make reliable measurements while reducing risk.

The 393 FC meets the test equipment safety requirements (IEC 61010-2-032) corresponding to the overvoltage category level (IEC 61730-1) for the electrical installation of photovoltaic arrays. It provides safe, accurate voltage measurement up to 1500 V dc in solar and battery applications, with features that help simplify work:

Its jaws are 25% thinner than those of the Fluke 37x clamp meter, making it easier and faster to measure in tight and crowded spaces

IP 54 protection for dusty and rainy outdoor environments

Fluke Connect™ collects data and stores it in the cloud for anytime, anywhere access

CAT III 1500 V insulated test leads are included

Carries Fluke's proven commitment to safety, durability, and reliability

Why use CAT Class III tools in solar installations? It comes down to security: keeping you safe. Don't entrust your (or your team's) protection to any tool that doesn't have the right level of security.

Why Use a CAT Level III Clamp Meter in a Solar PV Installation?

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