Raspberry Pi Helps a Hexapod Robot Walk

Roland Pelayo has used the single board computer, the famous Raspberry Pi or RBPi to help a hexapod robot learn to walk. The RBPi allows the robot to run in an autonomous mode, so it walks without assistance, avoiding obstacles. Alternately, it can also operate in a manual mode, whereby a user with a smartphone can control the robot. Most interestingly, the hexapod walker follows the tripod gait, just as most six-legged insects do.

Roland prefers to use servomotors to control the gait of the hexapod robot. According to Roland, using three servomotors to control the movement of the six legs of the robot, strikes a balance between performance and price. He added another servomotor for moving the eyes of the robot.

The servomotors allow the robot to move in four directions, forward, backward, left turn, and right turn. The robot moves by tilting itself to the left or the right, and then moving the leg lifted by its tilt. Roland has drawn diagrams explaining the movements of the robot. The backward and turn right movement of the robot is basically the reverse of its forward and turn right movement respectively.

Therefore, the front and corresponding back legs of the robot are interconnected to two servomotors, one to the left pair and the other to the right. The third servomotor helps to tilt the robot.

The RBPi allows the hexapod walker to operate in two modes. The first is the autonomous mode, which allows the robot to roam around freely, avoiding obstacles in its path. For instance, if it detects an obstacle in front, the robot walker takes two steps backwards, turns right, and then moves forward again. The second mode is for allowing the user control the movements of the hexapod robot using a smartphone on the same network as the robot is.

Roland has designed the program to allow the RBPi control four servos simultaneously, while reading inputs from a sensor detecting obstacles. The RBPi also connects to a network for the remote wireless control. Using an RBPi for the project was simpler for Roland, as the RBPi features on-board wireless connectivity.

Roland uses three Tower Pro SG-5010 servomotors, two for moving the legs and the third for tilting the hexapod walker. A fourth micro servo motor, a Tower Pro SG-90, helps to move the head and the eyes. An RBPi2 fitted with a USB Wi-Fi dongle helps to control the four servomotors. While the RBPi runs on a small power bank, the servomotors have their own separate power source. An ultrasonic sensor, HC-SR04, performs the obstacle detection.

As the echo produced by the ultrasonic sensor may cross the 3.3 V levels, Roland placed a voltage divider in between to connect to the RBPi, as its GPIO pins cannot accept voltages above 3.3 V.

As Python is already installed on the RBPi, Roland used it to write the program for the Hexapod walker. However, he also needed an extra library called pigpio, mainly for controlling the servomotors. He used SSH to access the RBPi remotely and installed the extra library.

Wash Your Solar Cells

To augment the energy supply, many are installing solar energy systems or residential solar panels. In general, these are flat units, placed at an angle on the rooftop. That naturally leads to the question of keeping them clean, which people equate to cleaning the roof itself. As this cleaning is usually left to the rainwaters, the next question comes as whether we should depend on the rains for cleaning the surface of the installed solar cells as well. Moreover, some also worry about whether water is good for the cells and will not damage them.

For these skeptics, scientists have a new type of waterproof solar cell that generates electricity even when compressed, stretched, or soaked in water. This is good news for those in the wearable solar cell industry. Wearable solar cells provide power to devices for monitoring health, usually as sensors incorporated into clothing, recording heartbeats, body temperature, and other parameters, for providing early warning of medical problems.

These extremely thin and flexible organic solar cells, or photovoltaic cells as scientists call them, are a result of research in the University of Tokyo. A material, by name PNTz4T, coats both sides of the cells with a stretchable and waterproof film. The researchers then deposit the cells within an inverse architecture of a one-micrometer-thick parylene film. After this process, the researchers applied an acrylic-based elastomer coating to both sides of the cell, which prevents water infiltration.

The elastomer is transparent and allows light to enter the cell, but does not allow air and water from leaking into it. This makes the solar cells longer lasting compared to conventional photovoltaic cells. The researchers decided to test the effectiveness of the coating by immersing the coated cells in water for two hours. They found the cells’ resistance to water to be high, as its efficiency to convert from light to electricity dropped by only 5.4 percent.

Next, the researchers tested the durability of the coated cell by subjecting it to compression. They compressed the cell by half for twenty cycles while placing drops of water on it. Even after surviving this brutal test, the researchers found the cell still had more than 80% of its original efficiency still intact. The above tests confirmed the cells’ mechanical robustness, high efficiency, and great environmental stability.

Not only as wearable sensors, these new washable, stretchable, and lightweight organic photovoltaic cells will also be suitable as long-term power sources as rooftop solar panels. Most experts do not recommend washing solar cells regularly for keeping the dust and debris from collecting on the surface. Since these new solar panels have the additional feature of being waterproof, there is no danger from giving them a frequent wash.

Experts feel it is best to let the rain take care of washing the solar panel. By monitoring the system functionality such as checking the energy bills and usage on monthly basis, the user can detect changes in the electricity bill. Another check can be made by visually inspecting the surface of the panels. If cleaning is necessary, washing it with a hose of water will do the job.

What is Optane Memory?

Optane is a revolutionary class of memory from Intel creating a bridge between dynamic RAM and storage for delivering an intelligent and amazingly responsive computing experience. For instance, Intel claims an increase of 28% in overall system performance, 14 times faster hard drive access, and two times increase in responsiveness in everyday tasks.

However, this revolution is not for everyone. It works only on the 7th generation Intel Core processor based systems that affordably maintain their capacity in mega-storage. For those using the above processor-based system, Intel promises Optane will deliver shorter boot times, faster application launching, extraordinarily fast gaming experience, and responsive browsing. However, there is a farther catch; you need to be running the latest Windows 10 operating system to take full advantage of Optane.

According to Intel, Windows 10 users on the 7th gen Intel Core processing systems can expect their computers to boot up twice as fast as earlier, with web browsers launching five times faster, and games launching up to 67% faster. Intel claims their Optane memory to be an adaptable system accelerator adjusting the tasks of the computer on which it is installed to run them more easily, smoothly, and faster. Intel provides an intelligent software for automatically learning the computing behavior and thereby accelerating frequent tasks and customizing the computer experience.

Intel’s new system acceleration solution places the new memory media module between the controller and other SATA-based storage devices that are slower. This includes SSHD, HDD, or SATA SSD. Based on 3D XPoint memory media, the module format stores commonly used programs and data close to the processor. This allows the processor to access information more quickly and thereby, improves the responsiveness of the overall system.

However, the Intel Optane memory module is not a replacement for the system Dynamic RAM. For instance, if a game requires X GB of DRAM, it cannot be divided between DRAM and Optane memory to meet the game requirements. Regular PC functioning will continue to require the necessary amount of DRAM.

For those who already have installed a solid-state disk or SSD in their computer systems can also install the Intel Optane memory for additional speed benefits. As such, the Intel Optane memory can extend acceleration to any type of SATA SSDs. However, the performance benefits are observed to be greater when the Intel Optane memory is used on slower magnetic HDDs, rather than when installed in systems with faster SSD-SATA.

Although other caching solutions exist, such as those using NAND technology, Intel’s Optane memory is entirely different. This new technology is a high performance, high endurance solution with low latency and quality of service or QoS. Optane uses the revolutionary new 3D XPoint memory media that performs well not only in low capacities, but also has the necessary endurance for withstanding multiple reading and writing cycles to the module.

In addition, Intel’s new Rapid Storage Technology driver, with its leading-edge algorithm, creates a compelling high-performance solution for a user-friendly, intuitive installation with easy to use setup process that automates the configuration to match the needs of the user.

Why do you need a Good Grounding?

Grounding is a safety measure for electrical and electronic systems whereby the user is protected from accidentally coming in contact with electrical hazards. For instance, refrigerators at home usually stand on rubber feet, even when operating from the AC outlet. Although electricity enters the refrigerator and runs through most of the electrical components within it, it has no connection to the outer metal body. Rather, the outer metal body of the refrigerator connects independently to a green grounding wire, which leads to the third pin (the thickest one) on the power plug.

If the outer metal body of the refrigerator was not grounded as above, and for some reason, electricity came in contact with the outer metal chassis such as from leakage, it would cause injury to anyone, if the person were to touch the refrigerator. Connecting the outer metal body to the grounding wire protects the person from being electrocuted, as electricity present on the metal body passes to the earth directly instead of through the person.

This is presuming the third pin on the power plug is connected to a good grounding arrangement outside the building. Typically, this arrangement is a ground rod, or a grounding electrode inserted into the soil. The arrangement works because the earth is a good conductor of electricity, and the overhead transformer that supplies power to the area, also has a grounding arrangement near it, which completes the circuit for the leakage current of the refrigerator. Therefore, a good grounding arrangement is essential for safety.

Apart from safety, most of the electronic equipment, such as computers, microwave ovens, LED lights, televisions, and more, need to be securely grounded to operate effectively. This is because most electronic equipment generate huge amounts of electrical noise that affect other equipment nearby. This can cause damage to an equipment, or cause it to work less effectively. Proper grounding helps to remove the unwanted noise, allowing all equipment to inter-operate more effectively.

Another advantage of a good grounding system is it helps protect against lightning. Lightning has high-voltage electricity with fast rise-times and causes large magnitude currents. A grounding system must present a low-resistance path for the high currents from a lightning strike to enter the earth, without causing damage to the building or equipment within.

Therefore, low resistance or low impedance of grounding is the key to protection from leakage of electricity, electrical noise, and lightning strikes. A good practice is to have all grounding connections as short and direct as possible, and connected with a heavy gauge wire, preferably made of copper. This ensures minimization of inductance and reduces the peak voltages induced.

The effectiveness of the grounding system in coupling the unwanted electricity to ground depends on a number of factors. This primarily includes the geometry of the ground electrode, the size of the conductors, the effective coupling into the soil, and the resistivity of the soil around the electrode.

Therefore, the basic requirements of any ground installation are to maximize the surface area of the electrode with the surrounding soil. This helps to lower the earth resistance and impedance.

Variables in Lead-Free Reflow for PCBs

Reflow ovens often show degrees of variability from profile to profile. This may depend on the distribution of components on the board, especially those that are slow heating, heat-sensitive, or of high mass. In general, reflow systems cannot generate one single reflow profile producing capable thermal results for all products.

For instance, a large BGA package on the PCB may not allow more than five degrees of variation near the peak of the reflow profile curve. Therefore, even while the BGA joints show good soldering, there is a probability of frying some other smaller components nearby the BGA package.

Variables during reflow can also be the result of several external factors. There may be limited control for some factors, but others could be uncontrollable. For instance, in some cases, the PCB may be non-uniform, its components may have varying thermal characteristics, or the tolerances of the process controller could be the major contributor. Even the exhaust could contribute as an external factor.

Oven loading is another major factor when creating custom reflow profile for a high-layer-count PCB. The reflow oven characteristics depend on the number of PCBs passing through it, as the total mass of the PCBs and their speed through the oven influences the rate of rise of temperature. Usually, the load capacity of the reflow oven is measured in boards per minute, and this value differs when only a single PCB is passing through as against a batch of several PCBs passing through at a time.

Customers often demand demonstrable settings of the custom reflow profile for their boards. It may be necessary to demonstrate that a given setting fulfills the requirements of a thermal profile for the board, without damaging any other component on it. Sometimes there are requirements to create documentation as evidence that a particular assembly is indeed within specifications. One of the advantages of creating custom profile for a board is it brings a total visibility to the lead-free reflow process when handling that board.

Automated Methods for Lead-Free Reflow

A reflow profiler, such as the one made by KIC, is the most popular method assemblers use for profiling groups of boards they assemble. The instrument works equally well when profiling individual boards automatically and continuously. Assemblers also use it for a cluster of boards consisting of two or three categories.

The KIC profiler has a Navigation prediction software accompanying it. This helps to drive the generated profile deeply within the specifications of the board. Typically, actual profiles need to be run on some boards that match the representative profile for that group. The process must be repeated periodically to ensure the settings remain valid. Used along with the Navigation prediction software, the KIC profiler saves much time and effort when creating lead-free reflow characteristics for high-layer-count PCBs.

Conclusion

Lead-free reflow of high-layer-count PCBs need not be a tiresome exercise provided it is possible to set up a custom reflow profile for a group of PCBs with similar thermal characteristics. Using modern thermal profilers makes the job economical and fast.

Storm Glass Lamp: Raspberry Pi Simulates a Storm

Several people have used the versatile single board computer, the Raspberry Pi or RBPi, as many types of educational devices. In fact, the original purpose of conceiving the RBPi was to use it as an educational instrument to further computer programming among children in schools. It has been serving this purpose excellently, and has managed to go even farther. For instance, the RBPi inspired someone to make a weather-simulation lamp for recreating the weather at any place in the world.

The RBPi within the Storm Glass lamp uses the API Weather Underground for accessing current and future predicted weather at any place in the world. At first glance, one may be rather skeptic about the project, especially when the current weather can be gleaned simply by looking out of the window. However, perception soon dawns when explained that the project is actually able to predict weather—observing tomorrow’s weather today. Alternately, it is possible to keep track of the weather in a distant location, say, a prospective holiday destination.

The designer created the cap and base for the lamp by 3-D printing them. The glass sitting in between the two actually belongs to that fancy mineral water bottle readily available in the supermarkets, which people casually overlook and are forever unable to justify buying. The base also holds the RBPi, a microphone, a speaker, and other varied components such as a NeoPixel LED Ring and a Speaker Bonnet from Adafruit.

The Storm Glass lamp uses two important arrangements. One of them is the rain maker and the other the cloud generator. The rain maker uses a tiny centrifugal pump working at 5 VDC to pump water via glass tubing into the lid, from where the rain falls. An ultrasonic diffusor/humidifier, also working at 5 VDC, forms the cloud generator. Only the electronics parts of the diffusor, which create the ultrasonic signal, are necessary, and the rest can be discarded. All the equipment goes in together into one spectacular lamp.

By installing Alexa Voice Service within the Storm Glass lamp, and setting it up to use the Weather Underground API to receive data related to weather conditions in a specified place, these conditions are easily recreated within the lamp, functioning as a home automation device.

When taken outdoors, and placed on a nightstand, the Storm Glass can actually recreated he weather conditions outside. It gives a weather forecast for the day by checking the weather periodically online. For instance, if the prediction for the day is rainy, expect some rain to fall within the Storm Glass Lamp. If the predicted says partly cloudy, you will see clouds forming inside, with some sunshine interspersed.

An RBPiZW powers the project, as it needs both Wi-Fi and Bluetooth support. Apart from the Speaker Bonnet, mini water pump, and the ultrasonic diffuser, there is a NeoPixel 12-LED ring, a 2.5 A micro USB power supply, 8 GB micro SD Card, two TIP 120 transistors and two 2K2 resistors. Additionally, you will also need tubing for moving water, lots of hot glue, and the 3-D printed parts to hold all the above together. All the parts operate at 5 VDC, so there is no additional converter, and the RBPIZW controls everything.

Lead-Free Reflow for High-Layer-Count PCBs

High-layer-count multilayer printed circuit boards (PCBs) present one of the most difficult cases for adaptation to the lead-free reflow assembly process. Often, these boards have through-hole and hand-soldered components, along with the requirement for two or more rework cycles. The slower wetting and higher reflow temperatures of lead-free solders place an enormous strain on the laminates and copper-plated hole barrels of the vias, with resulting loss of reliability.

Restrictions on Hazardous Substances

Printed circuits are coming under increasing requirements from environmental regulations. Waste Electrical and Electronic Equipment (WEE) directives and the European Union’s Restriction of Hazardous Substances (RoHS) are significantly affecting the requirements on the base materials used for manufacturing PCBs.

The most popular solder material so far consisted of the tin/lead (Sn/Pb) alloy. used for the assembly of PCBs for many years. The melting point of eutectic tin/lead alloy is 180°C and during assembly, reflow temperatures commonly reach peaks of 230°C. However, one of the major restrictions RoHS places is in the use of the element lead (Pb). This has resulted in development of alternatives to the tin/lead alloy, which are now replaced typically with the SAC alloy, whose primary ingredients are tin/silver/copper (Sn/Ag/Cu).

The SAC alloy has a melting point of 217°C, with reflow temperatures typically peaking around 255-260°C. This rise in the assembly temperature, coupled with the possible requirement of multiple exposures to these temperatures means the base material must possess improved thermal stability. Although there are several effects of lead-free assembly temperature on base materials, three effects deserve special attention for improving the thermal performance. These are:

* Glass transition temperature
* Coefficients of thermal expansion
* Decomposition temperature
*
How Higher Temperature Affects Laminates

The traditional Sn/Pb assembly process exposed the PCB to peak temperatures of 210-245°C, with 230°C being a very common value. At these levels, most lamination materials do not exhibit significant levels of decomposition.

However, at temperature ranges of 255-260°C where the lead-free assembly process operates, traditional lamination materials exhibit a 2-3% weight loss. Furthermore, multiple exposures to these temperatures may result in severe levels of degradation. Thicker boards, many of which are 20+ layers, aggravate the situation, as many of the layers are power or ground planes.

Although one of the simplest ways of complying with the RoHS directive of lead-free assembly may be to change the base laminate and replace the tin-lead solder, this does not work out satisfactorily for thick, complex, high-layer-count PCBs.

Creating Custom Reflow Profiles

Creating custom profiles for high-layer-count PCBs works well for the lead-free reflow assembly process. If the new PCB has thermal requirements close to that of some other PCB already being assembled, tweaking the settings for the existing PCB may be adequate. However, for a new PCB whose thermal requirements do not match any existing types, there may be thermal challenges. In such cases, developing a new profile may be more cost-effective ultimately.

Conclusion

Redesigning to reduce the thickness and the number of layers of high-layer-count PCBs is the way out in achieving reliable lead-free reflow soldering. Moving over to HDI technology, together with the use of BGA connectors, offers a viable solution.

How Counterfeit Electronic Parts and Components Affect Businesses

Although counterfeiting has been an age-old industry, it is only recently that the impact of counterfeit electronic parts and components has come to be highlighted. The public is slowly gaining the awareness of the implications and risks such counterfeited electronics bring to trusting users.

It is difficult for manufacturers to trace the origin of the counterfeited parts compared to the traceability present for the authentic components. It is possible these are older, but legitimate versions of the part, and someone has reprocessed them. On the other hand, these are legitimate fakes, which someone is trying to pass off as real. In both cases, their quality is highly suspect. Receiving counterfeit electronic parts or components in your business can result in mechanical and electrical defects, leading to financial risks and finally to loss of reputation and goodwill.

Mechanical Failures

Scrupulous elements recover a huge number of electronic components and parts from e-waste and reprocess them to sell as new. However, the stress of reprocessing these parts, especially integrated circuits, makes them susceptible to damage. As reprocessing elements do not usually follow proper manufacturing processes, they compromise the integrity of the components, and they occasionally fail to meet the stringent environmental requirements in the field.

Electrical Failures

While reprocessing, usually there is little or no effort to protect the component from ESD damage. Although the counterfeit component may be functioning in the circuit, it is difficult to predict when they will fail. The typical design of genuine electronic components allows them to function for a certain amount of time under specified conditions of use. Reprocessed parts generally fail as their useful life has been exceeded or they have endured dubious production controls and improper processing before they were resold as new.

Financial Risks

Counterfeit electronic components malfunctioning in the product or failing within the warranty period may lead to huge financial ramifications for the business. The financial risks may not be restricted only to simple replacements of the product, but may involve insurance compensations in case human lives are endangered, as could happen in premature failure of sensitive medical devices. The short-term savings from using counterfeit components may not be worth it, considering the financial backlash may turn out to be too huge for the business to handle.

Loss of Reputation and Goodwill

It takes a lot of effort to build up credibility, reputation, and goodwill in business, and these are essential for sustenance and growth of the business. However, the above can only happen provided the customers perceive the products to be of the quality and reliability the business claims they are. Counterfeit electronic components and parts leading to mechanical or electrical malfunctions and failures can easily undermine customer confidence in the business, leading not only to financial loss and legal hurdles, but also to loss of reputation and goodwill.

Conclusion

For safeguarding the business, its customers, its reputation, and goodwill, it is necessary for a business to take proper steps to prevent any incoming counterfeit parts and components.

What are Flexible Heaters?

Everyone is familiar with heaters. Although the simplest forms of heaters are sunlight and fire, both are not easy to handle or control. Therefore, people prefer using electricity for generating heat, as this is easy to control, requiring only a switch to shut off or turn on.

An electric heater generates heat by driving current through a resistive element. The power this arrangement consumes is the product of the resistance of the element and the square of the current flowing through it. The resistance radiates a part of the power it consumes as heat. This heat reaches other nearby surfaces through conduction, convection, or radiation, and transfers its energy to them, increasing their temperature.

Controlling an electric heater is a convenient way to keep the heated surface at a specific temperature or at least below a temperature that would cause damage. Initially, the resistive element of these heaters used simple nickel-chrome wires, as these could withstand high temperatures without melting. The heaters generally wrapped the wires around a mass and connected the ends to a power source. However, this arrangement, although effective, was not a practical solution for all applications.

Heaters have now evolved into flexible types, ones designed on flexible material, suitable for attachment to both flat and non-flat surfaces. Usually, temperature-sensing devices accompany these heaters, allowing constant monitoring and adjustments depending on the changes in the ambient surroundings. Flexible heater materials are commonly of two types—polyimide and silicon rubber—with flexible polyimide heaters being more popular.

Designers need to choose the conductor or the resistive element very carefully when designing a flexible heater. Flexible circuits commonly use copper as the standard cost-effective material, and this comes as a pre-laminated material. However, as copper is a good conductor, its resistivity is low. Therefore, heaters designed with regular copper require a lot of surface, and is suitable only for very low resistive designs.

Flexible heaters meant for producing high heat within small areas need a different material than regular copper for higher resistance. Designers thus use different types of nickel-copper alloys, such as Constantan or Inconel instead, which allow much higher resistive circuits within smaller areas. However, as nickel-copper alloys pre-laminated on a polyimide substrate are not commonly available, flexible heaters are more expensive.

The resistance of a heater depends on the target temperature of the material it is heating. After calculating the required resistance, the designer creates a pattern of interlocking serpentine traces of the correct width and length that emit consistent heat across the surface.

Some equipment, exposed to conditions of varying temperatures, use flexible heaters to keep their components at a consistent temperature. In cold countries, automobile manufacturers use flexible heaters for warming the steering wheel or the seat in their cars. Flexible heaters often keep biological samples at typical body temperature of a human or animal for better analysis. Flexible heaters keep batteries and electronics of aircraft warm when they have to operate at high altitudes. Flexible heaters keep critical components within ATMs and handheld electronic devices operating accurately in cold climates. This makes flexible heaters an important element in the electronic industry.

How is Solid Insulation Tested?

Engineers test solid insulation using two important test methods, and both use the Direct Voltage. One of the tests involves checking the resistance of the insulation, while the other tests the leakage current through the insulation at high voltages.

Insulation Resistance Testing

The instrument used for conducting this test is a megohmmeter. The instrument can be hand-cranked, motor driven, or electronic. Regardless of its principle of operation, a megohmmeter generates a direct voltage in the range of 100-15,000 V, and when applied to the insulation, indicates the material’s resistance in megohms.

As the resistance of any insulation material is temperature dependent, all readings need correction to the standard temperature for the class of the equipment under test. Usually, engineers refer to a table for the temperature correction factors for various electrical apparatus.

The value of the resistance of an insulation material is inversely proportional to the volume of insulation under test. For instance, a material a hundred feet long would have one-tenth the insulation resistance of another material a thousand feet long, provided all other conditions remained identical.

Engineers use this test typically to obtain an indication of deterioration trends of the insulation they are testing. However, the value of the insulation resistance by itself is no indication of the weakness of the insulation or the total dielectric strength of the material.

However, if the value of the insulation resistance showed a continuous downward trend, it usually points towards a contamination of the insulation, along with deterioration ahead. Therefore, engineers measure the insulation resistance in four common methods— short-time readings, time-resistance readings, polarization index test, and step-voltage test—to check for deterioration in the insulation system.

Short-Time Readings

This reading is only a rough check of the condition of the insulation. It measures the value of the insulation resistance for a short period, through a spot reading. The reading usually lies on the curve of increasing value of the insulation resistance. When comparing this value with the previous values, if a downward trend is indicated, then the insulation is deteriorating.

Time-Resistance Readings

All good insulation materials show a continued increase in the value of their resistance over the period when the voltage is applied. However, contamination with moisture and dirt decreases the resistance value of an insulation system, indicating contamination.

Indicating conclusive results of the state of the insulation, the time-resistance method is independent of the equipment size and its temperature. The state of the insulation system is derived from a ratio of the time-resistance readings.

Polarization-Index Test

This is a specialized application of the dielectric absorption test. Polarization Index is the ratio of the insulation test at 10 minutes to the insulation test at 1 minute. A ratio of less than one indicates the insulation is deteriorating and needs immediate maintenance. Usually, this test is reserved for dry insulation systems such as for cables, dry type transformers, rotating machines, and so on.

Step-Voltage Test

A controlled voltage method is used to apply voltage in steps to the insulation under test. If the insulation is weak, it will show a reduction in resistance that would not be apparent under lower voltage levels.