Page 46 - EngineerIT September 2022

NEW PRODUCTS AND SERVICES

Troubleshooting solar installations

F luke, locally represented by COMTEST, is experiencing increasing demand for

high-precision handheld devices which can measure photovoltaic (PV) systems.
The new-to-market Fluke 393 FC is the world’s only CAT III 1500 V rated
true-RMS clamp meter which enables technicians to take measurements in DC
environments, such as industrial solar farms. The tool was tailormade to test and
measure solar PV applications with key functions including: IP54 rating, which is
ideal for working outdoors on solar arrays and wind power systems, DC power
measurement with readings displayed in kVA, an audio polarity indicator, and logging
and reporting of test results via Fluke Connect software.
As solar distribution systems and loads become larger and more complex, the
implications for the safety of a technician become more important. It is critical
for technicians to understand the level of protection built into a tool and how to
use it when completing maintenance and troubleshooting. According to Fluke,
troubleshooting a PV system typically focuses on four parts of the system: the PV
panels, load, inverter and combiner boxes.
you can use the voltage and current to
1. Troubleshooting PV panels measure and record the power output in
A technician should first check the output of the entire system at the metering system kilowatt (kW). If possible, use the inverter
or inverter. Before commencing troubleshooting, also check and record the inverter’s display to show the current total energy
input voltage and current level from the array. in kilowatt-hours (kWh) and compare
The combiner box can be a great place to troubleshoot the system because the it to the one recorded during the last
individual wires from the modules return to it. Each module may have a fuse that inspection. When troubleshooting the DC
should be checked with the Fluke 393 FC. side, use the Fluke 393 FC to check the DC
Wiring problems and loose connections may cause a module to produce a voltage power and save the reading to the Fluke
that is too low. These can be traced out using the Fluke 393 FC to check wiring Connect™ app on your phone.
connections at the junction boxes. If the inverter does not produce
The Fluke 393 FC provides an audio polarity warning when testing Voc. If the right amount of power, there may
the polarity is reversed, it may mean that other circuits in the combiner box are be a blown fuse, tripped breaker or
unintentionally connected in series, resulting in voltages over the maximum inverter broken wires — all of which can easily be
input voltage. checked with the Fluke 393 FC.

2. Troubleshooting PV loads 4. Troubleshooting Combiner
Start by checking the load switches, fuses and breakers with the Fluke 393 FC to Boxes
see if the correct voltage is present at the load’s connection. Next, check the fuses When troubleshooting combiner
and circuit breakers. Find and replace blown fuses or tripped breakers. If the load boxes, amperage measurements and
is a motor, an internal thermal breaker might be tripped or there might be an open calculations are crucial to establishing
winding in the motor. For testing purposes, plug in another load and see if it operates whether the PV arrays are operating
properly. correctly. Measuring current on
As with any electrical system, check for broken wires and any loose connections. individual arrays or combining current
Clean all dirty connections and replace all bad wiring. With the power off, check for measurements will help determine if a
and repair any ground faults. If any fuses blow or breakers trip again, there will be a module has malfunctioned.
short that will need to be located and repaired. The thinner jaw design of the Fluke
If the load still does not operate properly, use the Fluke 393 FC to check the 393 FC clamp meter ensures several
system’s voltage at the load’s connection. The wire size may be too small and need conductors are used in the jaw for
to be increased. This will show up as a low voltage at the load and to resolve either combined current measurements, even
reduce the load on the circuit or run a larger wire. in tight or crowded spaces like inverter or
combiner boxes.
3. Troubleshooting PV inverters
The inverter converts DC from the PV system into AC power for building use. For Contact COMTEST on + 010 595 1821,
troubleshooting the AC side, use the Fluke 393 FC to check the inverter’s output sales@comtest.co.za or
voltage and current levels. Many of these systems have a display that indicates current www.comtest.co.za,
inverter and system performance. As the Fluke 393 FC produces a true-RMS reading, https://bit.ly/3J3vro3

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