Electronic Loads, Surge Protectors and Radio Interference explained

Solar Inverters

Solar inverters are devices which take in DC from a battery (or other DC source), and put out AC. Currently, all inverters are electronic devices, but mechanical inverters, e.g., a DC motor driving a generator are possible. An inverter is essential for using solar energy for mains driven devices. Inverters can be ‘pure sine wave’, ‘modified sine wave’, or ‘square wave’ types, in decreasing order of efficiency, complexity, and cost.

Electronic Loads

A load is anything which draws energy from a source. For example, an inverter is a load on the battery which is supplying it, while, the house-hold items driven off the inverter are loads on the inverter. The term ‘electronic’ will be normally applied to describe devices which are almost purely of semiconductor nature, e.g., stereos, computers, and LCDs. [caption id="attachment_6000" align="aligncenter" width="640"] Inside solar inverter - inverter quality inspection of components[/caption]

Surge Protection

All semiconductor devices have maximum allowable ratings in terms of voltage, current, and power dissipation. Power surges may occur on the grid due to transients caused by switching of high power machines, or due to grid faults, or lightening. Lightening can cause surges in a line even if it does not fall directly on that line. Inverters are regulated devices and will not cause any surges except when faulty. Most electronics equipment being designed currently has a built in protection against overvoltage (almost like a sacrificial animal!). Internally protected electronic devices, (and those which are of rather low cost) will not need any extra surge protection, except against lightening. When buying any sensitive (and costly) equipment one should check whether an external surge protector is required. Surge protector rating will depend on the equipment specifications. However, it will be a good practice to install a lightening protector in each household because no surge protector used in the household devices is likely to protect against nearby lightening..

Radio Interference

Radio interference is interference in the operation of radio devices. The term radio now includes all wireless transmitting and receiving devices, although the ‘ancient’ radio had a very limited bandwidth and application. Radio interference is generated because of the very laws which permit radio transmission and operation. It is very simple, and universal: Whenever current flows, it creates a magnetic flux around. And, whenever magnetic flux changes in the vicinity of a wire, it will cause a voltage in that wire. If the ends of the wire are connected across a device, e.g., a radio, it will apply a voltage on the device, and may cause an interference current through it. Hence, any sharp pulse of current has the potential to cause electromagnetic, or radio interference. With well protected circuits, lightening is the major source of radio interference. Localized interference may also be caused by overhead high power transmission lines, operation of faulty relays, and arcing.