Solar power is the conversion of energy from the sun to usable electricity. The most common source of solar power utilizes photovoltaic cells to convert sunlight into electricity. Photovoltaics utilize a semi-conductor to absorb the radiation from the sun. When the semi-conductor absorbs this radiation, it emits electrons, which are harnessed as electricity.
Advantages of Solar
Solar energy is a resource that is not only sustainable for energy consumption, it is indefinitely renewable (at least until the sun runs out in billions of years). Solar power can be used to generate electricity, it is also used in relatively simple technology to heat water (solar water heaters). Solar panels also require little maintenance. After installation and optimization they are very reliable, due to the fact that they actively create electricity in just a few millimeters and do not require any type of mechanical parts that can fail. Solar panels are also a silent producer of energy, a necessity if dealing with picky neighbors.
Disadvantages of Solar
Let’s start with the different types of solar panels currently on the market (mono-, polycrystalline and thin film) and list their benefits and downsides.
The term “solar panels” will be used to describe photovoltaic solar panels (the type that generates electricity), not solar thermal collectors.
How On-Grid or Grid-Tied Solar Energy Systems Work
What’s the difference between GRID TIE and OFF GRID solar systems?
Grid Tie means that your solar system is hooked into the utility company. Off the grid means you are not connected to the utility company.
It’s more efficient to be hooked to the utility grid because off grid systems must store the energy, as in batteries. If you are on the grid, the utility company stores the energy. The utility company keeps track of the kilowatts you use on an hourly basis. During a sunny day, you can produce more energy than you are using so your electric meter goes backwards and you build up energy credits. The goal of your solar power system on the grid is to produce as much power over a twelve month period as you use.
A revolution is taking place in how water is being pumped in remote locations beyond the reach of electric power lines. Solar-electric, or Photovoltaic, power has proven to be an ideal way to lift water for drinking, sanitation, stock tanks, and irrigation. Photovoltaic pumps have been on the market since 1980 and are in use all over the world.
It has been known for many years that some substances give off electrons when light strikes them and these electrons may be used to form a current. The development of photovoltaic (PV) technology began in 1955 and came of age in the 1980's. PV technology was initially regarded as "space age" because the use was limited to satellites, but in 1980 the cost was reduced by two-thirds making PV modules more affordable to the general public. PV technology is built on the solar cell. This small, paper-thin disc is made of silicon, an inert crystalline material refined from sand. Exposing the solar cell to sunlight causes electrons to jump from the positive to the negative side of the cell. Thus generating direct current. Solar cells are assembled into panels called modules. A solar panel will produce about 250 watts of power.
Solar water pumping provides a welcome alternative to fuel-burning generators for pumping and irrigation applications. The advantages of solar water pumping systems are many and some of the important ones are listed below.
· Solar pumping systems require no fuel. They are quiet, pollution-free and require little or no maintenance. Various facilities are available for automating the starting and stopping of water flow.
· Solar systems are expandable. A pump may be installed with the minimum number of modules. Later when economics allow, the system may be expanded to full flow capacity.
· Pumping systems are available and can be designed for small, medium and large scale water requirements. Many of the smaller sized systems cost little more than their fuel-powered equivalents.
· Solar electric powered pumping is extremely efficient. Maximum pumping power is available on sunny days when water is needed most.
· Low volume solar pumps offer the benefit of using slow water seeps in marginal wells.
· Solar pumps are very useful for lifting water from wells and pushing through pipelines that may be several kilometers long.
· When selecting a solar pumping system, the most important factors to take into account are well or borehole depth, yield of well, total vertical lift and total water requirements per day.
· A small solar system is comparable in cost to an engine powered system.
· Most larger solar systems initially cost more than fuel- powered systems but tend to be far more economic in the long run. For example, when determining the life cycle of a fuel-powered system, items such as the cost of fuel, parts, transportation and maintenance should be considered.
· A solar system minimizes future costs and cost uncertainties. The fuel is free and there is only one moving part.
How LED Streetlights Work
Amidst all the hubbub about tackling global warming and cultivating green energy, one subject receives little coverage: streetlights. While an important public service, streetlights are expensive to maintain and taken together, suck down a lot of energy. So when a city like Los Angeles announces that it's converting 140,000 streetlights to light emitting diodes or LEDs, and Pittsburgh states that it's considering doing the same with 40,000 lights, it's time to take notice.
LEDs are gaining traction as a great alternative to traditional lighting because they are relatively environmentally friendly, don't consume much electricity and have long life spans. They last so long 14 years or more in some cases that they can be considered "semi-permanent".
Some of the world's biggest electronics firms are now touting LEDs as the next big thing in lighting, whether in a small appliance or the biggest skyscrapers. By 2013, the LED market, which covers anything from holiday lights to those on the Empire State Building, was expected to be worth $1 billion.
Input protection is implemented in power supplies and DC/DC converters to ensure safe operation. The input fuse fitted within a power supply is not intended to be field-replaceable, it is rated such that only a catastrophic failure of the power supply will cause it to fail. It will not be cleared by an overload as the power supply will have some other form of overload protection, usually electronic. The fuse will often be soldered into the PCB rather than being a replaceable cartridge type fuse.
The power supply fuse is listed as a critical part of the safety approval process and is used to ensure that the power supply does not catch fire under a fault condition. If the fuse clears the most likely cause is that the converter has failed presenting a short circuit to the mains supply. In this event the fuse will clear very quickly.
As previously discussed, the fuse in the power supply is not intended to be field-replaceable, and should only be replaced by competent service personnel following repair. When using a component power supply, there will be additional mains wiring within the enclosure before the power supply and its fuse. This is where an additional fuse or circuit breaker as a protection device is fitted, to ensure that the wiring and associated components do not present a hazard.
With the convergence of information technology equipment (ITE), communication technology equipment (CTE) and audio/video equipment using common technology, cross platform architecture and use in similar environments, a new safety standard has been developed to replace the familiar 60950-1 and 60065 standards. The new standard is hazard based and in several years time will be mandatory to use in demonstrating conformity to the Low Voltage Directive when the current standards are withdrawn in 2019.
62368-1 has been developed by the international standards organisation IEC and has already been adopted by the US and Canada for several years as CSA/UL62368-1. The adoption in Europe has been delayed due to changes required by some member states however it now appears in the Official Journal of the European Union as a harmonised standard under the LVD, 2014/35/EU as EN62368-1:2014. This means that it can optionally be used from now to demonstrate compliance with the Directive but will be mandatory on 20th June, 2019. At that date, EN60950-1:2006 + A2:2013 and EN60065:2014/AC:2016 will be withdrawn and will no longer be available for use. It should be noted that Asian countries are still considering the new standard and for the time being it has not been adopted resulting in the need to still use the old standards for approval of equipment destined to Asia or which will require CCC for China, or KT for Korea, PSE of Japan or BSMI for Taiwan approval etc.
62368-1 is a hazard based standard and not a risk based one such as the medical 3rd edition of 60601-1 so will not require risk analysis reports to be prepared. It allows for ‘prescriptive construction’ in the same manner as 60950-1 but also allows for performance orientated results based on testing to demonstrate compliance which should simplify the certification of new technologies.
Rail applications demand that equipment is able to withstand the harsh climatic, mechanical and electrical environments encountered on traction vehicles and rolling stock. Electronic equipment, from lighting through passenger information and entertainment, to control, safety & engine management systems require DC/DC power conversion and must perform safely and reliably.
Within Europe, many countries historically developed their own national rail standards such as the BRB/RIA standards commonly used in the UK and the NF F 01-510 for applications in France. With the privatization of national rail companies, and the general move to harmonization of national standards within the European Union, two standards for electronic equipment (EN50155 & EN50121) have largely replaced the older national standards, though the older national standards are still occasionally required and cannot be entirely dismissed.
The most frequently cited design specification is the European Norm EN50155 “Electronic Equipment used on Rolling Stock”. The key elements when considering the selection of DC/DC converters and power sub-assemblies are:
Medical electrical equipment : General requirements for basic safety and essential performance – Collateral Standard: Electromagnetic disturbances – Requirements and tests
A new version of the medical EMC standard IEC60601-1-2 was published in 2014, widely referred to as the 4th Edition.
There are two main aims of the revisions. One is to improve immunity of equipment partly due to the proliferation of wireless communication devices operating within the local proximity of what may essentially be life critical equipment. These wireless devices may take the form of mobile phones, blue-tooth, WiFi, Tetra, RFID or paging system products.
The second aim is to introduce an element of risk analysis into deciding which levels of immunity are suitable for the equipment, its intended operating environment and foreseeable levels of disturbances. This is due to the inclusion into the standard of equipment intended to operate outside of hospital environments in which there is less supervision of equipment and less control over the electro-magnetic phenomena present. Part of the risk approach is that manufacturers must be clear about the essential operation of their product and mitigate the risk of failure or abnormal or unexpected operation by choosing the appropriate immunity levels which may be higher than indicated in the following table.
“My 10 kV power supply has an isolation rating of only 3500V, why is that?” This is a common initial reaction when reviewing the data sheet of a high voltage power supply. This note intends to explain why.
First, an explanation of the basic function blocks of the supply should help. In a typical DC to high voltage DC converter, the DC input feeds an inverter, which drives a step-up high voltage transformer, which drives a rectifier. See Fig. 1
If this was the extent of the circuit, then the isolation rating of the supply should be higher than the high voltage output of the supply. However, here’s where things get a little more interesting. The high voltage output of the transformer is then typically used to drive a Cockroft-Walton voltage multiplier circuit, which does just that; it multiplies the output of the transformer. See Fig. 2.
Demand for power supplies that can withstand harsh environmental conditions does not only come from defense applications. Telecommunications base stations and infrastructure for the smart electricity grid of the future place steep demands on power supplies. These systems are subject to the extremes of temperature, dust and humidity.
Equipment needs to operate continuously as well as reliably, since performing maintenance at remote locations can be difficult, expensive and downtime is unacceptable. Sealed enclosures to prevent dust and moisture ingress are often used to protect the system from its environment, but this poses a problem for thermal management of power supplies.
A common power supply cooling solution when using a sealed enclosure is to use a small convection cooled power supply and over-rate it. For example, if you take a power supply that is rated for full power at 50°C ambient temperature, it might derate by 50% at 70 °C. So for operation at the elevated temperature, a power supply rated for twice the actual output power would be needed.
For the high power levels that are required for smart grid infrastructure or a telecoms base station, it’s not feasible – in this example, a system that requires 500 W would need a 1000 W convection cooled power supply, which is impractical from a size and cost point of view. If high power requirements have ruled out convection cooling, another of getting heat out of the box must be considered.
Sealed enclosures prohibit forced air cooling as fans can suck in dirt and dust. Filtering is possible but this cuts down the air flow significantly, meaning a larger fan is needed, and they are susceptible to blockages.
This affects the reliability and maintenance demands of the system. An alternative solution is therefore required to get the heat from the power supply out of the box; using a baseplate cooled unit is a simple and inexpensive way of doing this.
Automation - Industry term commonly used to describe the mechanization of various aspects of die casting process.
Biscuit - Excess of ladled metal remaining in the shot sleeve of a cold chamber die casting machine. It is part of a cast shot and is removed from the die with the casting.
Blister - A surface bubble caused by gas expansion (usually from heating) which was trapped within the die casting or beneath the plating.
Die cast tooling called insert die, die casting dies, or die casting molds, comes in many styles, sizes, and values. Die cast tooling comes in single cavities (one part each cycle) or multiple cavities (more than one part each cycle). INOVIA Technologies only uses cold chamber die casting machine tooling dies or molds for aluminum die cast parts. Die cast tooling costs from as little as a few hundred dollars for trim dies, a few thousand for cavity inserts, to several thousand dollars for a large part complete die cast die tool package.
Die casting is a manufacturing process in which molten metal is injected, under pressure, into a hardened steel die or also called mold. Dies are often water-cooled. Dies are then opened, and the die castings are ejected (many times thousands of parts each day, sometimes only a few hundred). Once the tooling is paid for, die casting is a very inexpensive aluminum part manufacturing process.
When someone asks “what is draft angle in a box?” or “why do I need a draft angle on my aluminum die casting box part?” The technical answer is, all aluminum die castings require a draft angle on the walls of die cast box parts perpendicular to the parting plane or parallel to the slide interfaces. Since INOVIA Technologies have been selling die cast parts for over 20 years, We find a simple answers and provide simple calculations for our customers. What does that mean to the typical engineer (any engineer other than tooling or mechanical) or professional buyer?
Plastic moulding is the process of shaping plastic using a rigid frame or mould. The technique allows for the creation of objects of all shapes and sizes with huge design flexibility for both simple and highly complex designs. A popular manufacturing option, plastic moulding techniques are responsible for many car parts, containers, signs and other high volume items.
Plastic Moulding Techniques
While there are many plastic moulding processes and techniques, here we will discuss only the techniques of rotational moulding, injection moulding, blow moulding, and compression moulding. However, the following article entitled "Your Guide to Plastic Molding" is a good overview for the various plastic moulding processes.