Technical library

This application note looks at what you should check when analysing the power quality data from a solar panel application.

When examining potential power quality issues associated with solar panels, your power quality analyser should be programmed to examine a variety of different parameters outlined in this application note.

Renewable energy sources can include solar photovoltaic (PV), solar hot water, geothermal, wind and biomass. Of all of them, solar prices are dropping the quickest, so we are seeing this industry grow the quickest. This is most notably true in the residential and small commercial markets.

The most significant danger facing wind turbines is damage from lightning strikes. Lightning faults cause more loss in wind turbine availability and production than the average fault. The number of failures due to lightning strikes is known to increase with tower height and a growing number of studies speculate that rotating wind turbines may be more susceptible to lightning strikes than stationary structures.

Megger provide a range of lead sets and clips of different sizes and electrical characteristics for use with Megger 5 kV and 10 kV insulation resistance testers, enabling the user to choose the most applicable lead set for the work in hand.

 Harmonics are caused by non-linear loads. Linear loads draw a linear current that follows the changing voltage of the AC waveform. Non-linear loads draw current pulses periodically, which creates distorted waveforms.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 10.0px Times} span.s1 {font: 10.0px Helvetica} Since there is no such thing as perfect insulation, if any conductor is raised to a potential above that of earth some current is bound to flow to earth from that conductor. The amount of current that flows is dependent on:Voltage on the conductorThe capacitive reactance between the conductor and earthResistance between conductor and earthCurrents that flow to earth are called leakage currents and are usually very small values, typically < 1 mA. However the amount of current that is required to cause distress or harm to a human being or animal is also small, these currents must be limited by circuit design to safe values.If this is not possible, then a 30 mA RCD (residual current device) or 30 mA RCBO (residual current device with overload protection) should be fitted for personal protection.

A Portable Appliance Tester (PAT) is an instrument that is dedicated solely to the safety testing of portable electrical equipment in accordance with recognized national and local standards. Depending on locale, these standards may have been enacted into law. They may be requirements of specific industries or trade organizations, or just a good idea. In many cases, manufacturers of electrical consumer products who wish to export to foreign markets will be required, sometimes by national law, to assure the products have been safety tested. If testing is performed at time of manufacture, it will save money, aggravation and ill will that could result from having the products fail in the destination country. 

When testing appliances with long power cords, usually longer than 5m, it can be necessary to allow for the additional cord resistance. Most modern Portable Appliance Testers have pre programmed pass limits. These are based on the limits specified in the Code of Practise for In-Service Inspection and Testing of Electrical Equipment. However, the true pass limit depends on the appliance to be tested. The pre-programmed limit may not be suitable for all appliances. Moving the goal posts can be justified in particular circumstances when a test initially fails.

A comprehensive guide to testing power quality.