Clamp Meter - How to Diagnose PV System Faults? Do you know the three typical questions?
In many factories and facilities today, there is a need for HVAC technicians who know how to troubleshoot and troubleshoot photovoltaic (PV) systems. Factories are looking for ways to reduce energy dependence, and they are increasingly turning to renewable energy sources, such as solar PV.
The three most common types of PV system problems that require troubleshooting and troubleshooting are related to panels, loads, and inverters. For the HVAC technician, the most handy tool is a true rms AC/DC clamp meter.
Fault diagnosis and troubleshooting of PV panels
First check the output of the entire system at the metering system or inverter. Before climbing on the roof, check and record the array's inverter input voltage and current levels. You may encounter the following two situations:
1. The entire PV system is paralyzed/no power generation; this may be related to inverter problems.
2. The output of the PV system is lower than expected; this may be related to an array problem or a module problem.
Beginning at the concentrator, trace the individual branch wiring upwards. Once you are on the roof, visually inspect the entire system for any obvious damage. (Wires may have been accidentally disconnected while servicing another piece of equipment.) Once you've located the faulty module or array, check all wires, switches, fuses, and circuit breakers. Replace blown fuses; reset circuit breakers and switches. (Because the PV system is on the roof, a lightning strike or power surge could affect it.) Check for broken wires and loose or dirty connections. Replace and clean as needed. Note the wire nuts of the connection modules. May loosen and cause poor contact.
The concentrator is a good place to troubleshoot the system because the wiring from the various modules returns here. Each module may have a fuse which should be checked with a Fluke 376 FC.
Wiring problems and loose connections can also cause the module to produce too low a voltage. All wiring connections should be checked. If the output of the module is too low, it may mean that some part of the battery is bad. You can use a trace at the junction box until you find the faulty part.
Dirt on the modules or modules that are in the shade may cause reduced output. Although modules are generally designed to be maintenance-free for many years, cleaning may be required.
Fault Diagnosis and Elimination of PV Loads
The PV system is used to drive the building's electrical loads, and any problems with the loads will also affect the system. The first step is to check the load switch fuse and circuit breaker with a clamp meter to see that the correct voltage is present at the load connection. Then check the fuse and circuit breaker with the clamp meter FC. If a fuse blows or a circuit breaker trips, locate the cause and repair or replace the faulty part. If the load is a motor, the internal thermal circuit breaker may have tripped, or there may be an open winding inside the motor. For testing, plug in another load to see if it works.
As with any other electrical system, check for broken wires or loose connections. Clean any dirty connections and replace any bad wires. Turn off the power, check and repair any ground faults. If any fuses or circuit breakers blow or trip again, there may be a short circuit that must be located and repaired.
If the load still does not work properly, check the system voltage at the load connection with the clamp meter FC. The wire gauge may be too small and need to be increased. It is also possible that the cable connected to the load is too long, which also causes the voltage at the load to be low. In this case, reduce the load on the circuit or use a larger cable.
Fault Diagnosis and Elimination of PV Inverters
You probably deal with variable speed drives on a daily basis, so check AC and DC power frequently. Inverters in PV systems can also fail and cause malfunctions. The inverter converts the DC power from the PV system to AC power for the building. If the output from the inverter is incorrect, first check and record the DC input voltage and current levels of the inverter. On the AC side, check the output voltage and current level of the inverter with a clamp meter FC. Many of these systems have display screens that indicate current inverter and system performance. Because the FC produces true rms readings, you can measure and record power (kW) output in voltage and current. If possible, use the inverter screen to display the current total kilowatt-hour (kWh). Then record that value and compare it to the value recorded the last time you checked.
