This rapid expansion is accelerating the search for ways to reduce the risks involved in commissioning and installing photovoltaic systems. The resulting demand for highly accurate portable devices capable of taking safe and reliable measurements in these applications is now being met with the introduction of the first CAT III 1500 V true RMS clamp meter: the Fluke 393 FC.
In photovoltaic applications, the current is very high and not limited by electronics, making it vital to choose the right solar installation testing equipment to protect workers and the photovoltaic system itself from a range of potential electrical hazards.
1. Electrocution.
The Fluke 393 FC helps provide protection against the three major electrical hazards: electric shock from live conductors, and electrical arcs and flashes that cause fires and explosions. Control measures and best practices to mitigate these risks differ when working with photovoltaic systems compared to working with any other type of power source. Therefore, it is important that multimeters, test leads, and fuses are of the appropriate rating for the application.
Electric shock or electrocution from live conductors can occur when current accidentally passes through the human body, with lethal results from as little as 50 milliamperes (mA) over the heart. Electric shocks are often caused by improper wiring insulation, deteriorated insulation on safety covers, or inadequate grounding. In a photovoltaic system, these situations are most likely to occur at the combiner box, the equipment grounding conductor, the photovoltaic array, and the output circuit conductors.
2. Electrical Arcs.
Electrical arcs that trigger fires are high-power electrical discharges between two or more conductors; the discharge generates heat that can damage or even burn the insulation of the wiring. Photovoltaic systems are especially vulnerable to electrical arcs caused by a break in conductor continuity or by an unexpected current between two conductors, often due to a grounding failure.
Arcing is a phenomenon common in large photovoltaic installations with medium and high voltage levels. Arcing has become a DC problem since the development of large-scale solar power systems; therefore, arc flash risk analysis must now be performed on DC systems above 120 V. This issue arises particularly when testing voltage combiner boxes, when using photovoltaic supply circuits in parallel to increase current, or when testing switching equipment and medium- and high-voltage transformers. An arc flash occurs when a significant level of energy is available in DC and AC conductors. The flash emits hot gases and radiant energy on the order of 19,500°C (or four times the temperature of the sun's surface). The greatest risk is concentrated in residential inverters with an input voltage up to 500 V and in large inverters up to 1500 V. It is essential to use an instrument with the appropriate measurement category (CAT) and voltage level for the application. In this way the instrument will be able to handle medium voltage levels and high voltage peaks and transients that can generate electrical discharges or arcs.
3. Switching to 1500 V
Major inverter and solar module manufacturers are moving from 1000 V to 1500 V systems to achieve significantly higher efficiency. CAT III 1500 V systems are becoming increasingly common in solar installations, while CAT III and CAT IV equipment is essential for high-altitude photovoltaic systems. Only the Fluke 393 FC True RMS Solar Clamp Meter meets the insulation requirements of these CAT III environments.
This instrument is specifically designed for use by photovoltaic system installation and maintenance technicians working in high-voltage DC environments. The clamp can measure up to 1500 V DC, 1000 V AC, DC power, and current up to 999.9 A DC or AC through a slim jaw that is ideal for the tight spaces often found in combiner boxes or inverters. Another notable feature of the clamp, which has a three-year warranty and IP54 protection (making it suitable for outdoor use), is its acoustic polarity indicator, which helps prevent accidental wiring errors, thus ensuring the correct installation of the photovoltaic panels.
Polarity functions and audible and visual polarity checks are essential during the commissioning of a new installation, whether it involves a combiner box or an inverter. Checking DC polarity makes it easy to identify the polarity of the strings if they have been accidentally reversed, thus preventing the risk of fire in the combiner box, as well as potential damage to equipment and danger to personnel.
Safe, reliable, and rugged.
All test results are recorded and transmitted via Fluke Connect software installed on the Fluke 393 FC True-RMS Solar Clamp Meter. Using just a mobile phone, engineers can quickly take and save measurements; the phone can record for 10 minutes and send the readings to colleagues. This safe, reliable, and rugged instrument, capable of measuring and recording for up to two weeks, also comes with an 18-inch iFlex flexible current probe to extend the AC current measurement range up to 2500 A. The test leads are also CAT III 1500 V DC rated.
Hans-Dieter Schuessele, Fluke's EMEA Applications and Technology Expert, stated: “Safety is paramount in the commissioning and installation of photovoltaic systems. The electrical power of the future requires instruments capable of keeping you safe in harsh environments; risk is unacceptable, and you must literally rely on your instrument to protect your life. That's why the world's first CAT III 1500 V true-RMS clamp meter has been designed to offer enhanced protection to users in demanding CAT III environments. It is crucial to have a robust instrument that incorporates numerous features capable of operating at these levels: the solar industry urgently needs a solution like the Fluke 393 FC.”
