Name: safe handling of high-voltage lab power
Uploaded: 2023-04-30T06:39:49.000Z
Duration: 9 min 36 s
Channel: JoVE

K12 Standards

Arizona Science Standards

High School

Physical Science

HS+Phy.P2

HS+Phy.P2U1.1

electrical-safety-precautions-and-basic-equipment

Electrical Safety Precautions and Basic Equipment

Safety Precautions
1. Electric Power and Experimental Setup
<ol>
	<li>Avoid loose wires, cables, and connections.</li>
	<li>Assume any exposed metal is live with electricity unless otherwise verified.</li>
	<li>Familiarize oneself with all ON/OFF buttons on equipment, circuit breakers, and disconnect switches of a bench.</li>
	<li>Only make changes to the experimental setup when the circuit power is turned off and all power sources read zero voltage and zero current, as applicable.</li>
	<li>Use wires of suitable length for their appropriate applications. Long wires or connections can cause clutter on a bench, and very short wires or connections can be too tight and may be easily disconnected.</li>
	<li>Separate higher power equipment and connections from lower power equipment, such as microcontrollers, to avoid both interference and electrical interconnections between sensitive electronic devices and higher power devices.</li>
	<li>Make sure that all DC power supplies, AC sources, and other power sources start from a zero voltage and zero current output or as directed in an experiment. Starting from a non-zero voltage is possible in certain applications where a voltage source should have a specific initial condition.</li>
	<li>Turn off all equipment before leaving the lab once an experiment concludes.</li>
	<li>Do not allow a single user to perform an experiment alone. Make sure at least two users perform an experiment when operating more than 50 V DC and three-phase AC.</li>
</ol>
2. Work Environment
<ol>
	<li>Familiarize oneself with the exits in the laboratory.</li>
	<li>Avoid a cluttered work environment.</li>
	<li>Have a pen, calculator, lab notebook, and experiment description prepared and ready.</li>
	<li>Appropriately cool and label warm (due to heat dissipation) equipment.</li>
</ol>
3. Clothing and Personal Requirements
<ol>
	<li>Remove jewelry, metal watches, or other metal accessories while performing any experiment, as these can be dangerous in the vicinity of rotation machinery and electrical connections.</li>
	<li>Do not wear loose apparel, shorts, or short skirts, as they expose skin to electrical connections and rotation machinery.</li>
	<li>Do not wear hanging necklaces, glasses, ties, and other accessories, as users tend to get close to rotating machinery and electrical connections. Also, avoid hanging glasses around the neck, which can be easily grabbed by rotating machinery.</li>
	<li>Tie long hair to the back of the head.</li>
	<li>Wear safety goggles at all times during the experiment. Wear other personal protective equipment (PPE) as required by local safety rules and regulations. For example, common PPE includes fire-retardant coats, high-voltage insulating gloves (worn when handling live wires or cables), and earplugs (used when operating loud machinery).</li>
</ol>
Basic Equipment: Demonstration and Overview of Electronic and Measurement Equipment
4. Function Generator
<ol>
	<li>Turn on the function generator (Fig. 1). Function generators provide periodic AC signals of different shapes. These shapes are mainly sinusoidal, triangular, saw-tooth, and square.</li>
	<li>Set up the function generator to produce a sinusoidal output of 10 V peak at a frequency of 400 Hz and zero DC offset.</li>
	<li>Connect a BNC-to-alligator connector with the BNC tied to the function generator output port.</li>
	<li>Adjust the frequency and peak, or peak-to-peak, of these signals if desired.</li>
	<li>On triangular and saw-tooth signals, adjust the slope and shape. Square waveforms have adjustable duty cycle, which is defined as the proportion of the period during which a square waveform is positive or "high" versus negative, zero, or "low".</li>
	<li>Note that certain function generators provide non-periodic noise and random signals, but these are not commonly used in power electronics and electric machines applications.</li>
</ol>
<img alt="Waveform generator setup, displaying 5V output, used for voltage signal generation experiments." src="/files/ftp_upload/10114/10114fig1.jpg" data-altupdatedat="1761830439000" data-alt="Figure 1"> 
Figure 1: Close-up of function generator screen and control panel. <a href="//cloudfront.jove.com/files/ftp_upload/10114/10114fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
5. DC Power Supply
<ol>
	<li>Turn on the DC power supply (Fig. 2). Low-power DC supplies operate in two main modes - either voltage sources or current sources.</li>
	<li>Observe the voltage and current readings.</li>
	<li>Set the DC power supply output voltage to 10 V by adjusting the output voltage knob. Operating as a voltage source is the most common, where the supply provides low voltage DC; typically ranging between 0 and 36 V. In a current source operation, these supplies are "current limited" where their maximum current is set to the desired value, and their voltage is automatically adjusted to provide the desired maximum current. Current and voltage limits thus provide operational flexibility as well as safety margins when operating a DC power supply.</li>
	<li>Press the "Current" button to display the current limit and adjust the current knob to adjust the maximum current limit. Set the current limit of the supply.</li>
	<li>Note that most single-output DC power supplies have three terminals labeled as "+," "-," and ground. In many applications, "-" and ground are tied to provide a more stable and reduced noise environment when providing an external circuit with power. However, certain cases require that "-" is floating from ground to isolate the electrical circuit or apparatus under test from the supply ground.</li>
</ol>
<img alt="DC power supply setup; voltage, current controls for electronics experiments and circuit testing." src="/files/ftp_upload/10114/10114fig2.jpg" data-altupdatedat="1761830439000" data-alt="Figure 2"> 
Figure 2: DC power supply unit. <a href="//cloudfront.jove.com/files/ftp_upload/10114/10114fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
6. Oscilloscope
<ol>
	<li>Turn on the oscilloscope (Fig. 3). Oscilloscopes, or scopes, display voltage and current waveforms on a screen, which provides a wide range of essential measurements.</li>
	<li>Connect a regular probe (Fig. 4) to channel 1 and a differential probe to channel 2. Oscilloscope probes connect to the BNC connectors on the scope interface, and each channel displays a single waveform. Every scope comes with a variety of channels. The most common are two- and four-channel scopes, but newer scopes can have eight channels.</li>
	<li>Remove any offset on channel 2.
	<ol>
		<li>Oscilloscope probes are used most often with electric machines and power electronics experiments. The main types of probes include the conventional grounded probe, the differential voltage probe (Fig. 5), and the current probe (Fig. 6).</li>
		<li>Use conventional grounded probes when measuring voltage across two points in a circuit or apparatus, where one of the points is tied to earth ground. Typically, the grounded part of the scope is an alligator clip, and the other test lead is a hook that ties easily to circuits and electrical components.
		<ol>
			<li>Never use these probes with ungrounded connections, as a short circuit to ground will occur, causing risk to the user, sparks, and damage to the probes. Usually, these probes are rated to several hundred volts.</li>
		</ol>
		</li>
		<li>Use differential voltage probes to provide isolation between the earth ground and both test points, across which voltage is being measured. These probes are essential when neither of the points are grounded (e.g. when measuring across two of three phases in a three-phase voltage source). Such probes are more expensive and require manual or automatic offset adjustment before every use, as a form of basic calibration. They are less robust to noise due to the lack of grounding on the probe test leads. Their voltage ratings in educational labs typically reach 1000 V.</li>
	</ol>
	</li>
	<li>To measure current in a wire, place the wire in the window of the current probe and ensure that the wire is locked within the probe hole. Adjust the probe scaling (e.g. 100 mV/A) on the probe enclosure and note the scale. Current measurements are displayed as voltage measurements.
	<ol>
		<li>A wire carrying AC or DC current passes through the core, generating a magnetic field, which induces voltage on the wire winding wrapped around the core. This gives a voltage measurement proportional to the current in the wire, and current can be measured using this probe. These are typically even more expensive than differential voltage probes and can range up to 100 A in educational labs. Many educators and researchers replace them with sensing resistors that have very low but accurate resistance. Sensing resistors pass current proportional to the voltage across their terminals, and by Ohm's law, measuring the voltage while knowing the accurate resistance gives an accurate approximation of the current.</li>
	</ol>
	</li>
	<li>Connect the regular probe terminals to the alligator side of the function generator's output.</li>
	<li>Turn on the function generator output.</li>
	<li>Adjust the time axis scale by using the "sec/div" knob on the scope to zoom in and out of the displayed channel 1 waveform. Each scope may have a different approach to adjust the display, but all common scopes have two major divisions to set. On the x-axis (time-axis), divisions resemble a certain period of time and can vary from µs-per-division to several seconds-per-division.</li>
	<li>Adjust the y-axis of channel 1 by using the channel 1 knob. Use the "volts/div" knob to adjust which divisions on the y-axis show volt readings. Each waveform has a unique y-axis scaling knob.</li>
	<li>Press the "measure" feature button on the scope to measure the frequency and peak-to-peak of the displayed waveform on channel 1. This can also be used to find the measurements of the mean, root mean square (RMS), and period of a signal.</li>
	<li>Press "math" to use mathematical functions; such as addition, subtraction, or more advanced functions using more than one waveform displayed on the scope. For example, it is useful to show the product of instantaneous voltage and current in order to see instantaneous power.</li>
	<li>Trigger manually by adjusting the "trigger" knob, or automatically by pressing "Set level to 50%." Select the scope channel from which all waveform displays are triggered. By using the appropriate trigger level, the jitter in the displayed waveforms is eliminated; so all waveforms look stationary and clean.</li>
	<li>Press "cursor" to measure the distance between two points on either the time-axis or y-axis.</li>
	<li>Press the "CH1," "CH2," or other channel buttons, and select the appropriate digital filter to eliminate noise from the waveform display. Low-pass filter corner frequencies are preset and may differ in different scopes.</li>
	<li>Adjust the function generator output until the desired amplitude and frequency are achieved.</li>
	<li>Turn off the function generator and disconnect the scope probe.</li>
	<li>Turn off the oscilloscope.</li>
</ol>
<img alt="Oscilloscope display with waveform; voltage measurement; electronic signals analysis; data output." src="/files/ftp_upload/10114/10114fig3.jpg" data-altupdatedat="1761830439000" data-alt="Figure 3"> 
Figure 3: Oscilloscope unit. Close up shows screen and control panel. <a href="//cloudfront.jove.com/files/ftp_upload/10114/10114fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Oscilloscope probe setup on wooden table, used for measuring electrical signals in circuits." src="/files/ftp_upload/10114/10114fig4.jpg" data-altupdatedat="1761830439000" data-alt="Figure 4"> 
Figure 4: A conventional grounded probe. <a href="//cloudfront.jove.com/files/ftp_upload/10114/10114fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Differential probe equipment for voltage measurement, showing settings and warning labels." src="/files/ftp_upload/10114/10114fig5.jpg" data-altupdatedat="1761830439000" data-alt="Figure 5"> 
Figure 5: Differential voltage probe. <a href="//cloudfront.jove.com/files/ftp_upload/10114/10114fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Current clamp sensor for measuring AC/DC current in electrical circuits, shown on wooden surface." src="/files/ftp_upload/10114/10114fig6.jpg" data-altupdatedat="1761830439000" data-alt="Figure 6"> 
Figure 6: Side view of current probe.  <a href="//cloudfront.jove.com/files/ftp_upload/10114/10114fig6large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
7. Multimeter
<ol>
	<li>Turn on the multimeter (Fig. 7) and make sure that its terminations are in the voltage measurement connection position. Multimeters, whether handheld or bench-top, measure the average value of a DC voltage or current, or the RMS value of an AC voltage or current. Carefully revise the connections to measure voltage or current before powering a circuit, as these connections are a common source of error when performing an experiment.</li>
	<li>Turn on the DC power supply output with no banana wires placed at its output ports.</li>
	<li>Use the multimeter to measure across the two output ports (+ red and - black). To enhance the measurement resolution, manually adjust the signal range up to 10 V or 1000 V.
	<ol>
		<li>The multimeter should read 10 V.</li>
		<li>Note that multimeters include other measurement features, such as the resistance between two points and the direction of current flow (diode symbol), which is useful in debugging diodes and transistors.</li>
	</ol>
	</li>
	<li>Use digital power meters to measure average power. Digital power meters are similar to multimeters but use concurrent voltage and current measurements to measure average power. Advanced meters can measure power factor, reactive power, and apparent power.</li>
	<li>Connect two voltage leads across (in parallel with) the two points where voltage should be measured.</li>
	<li>Connect two current leads in series with the wire or component.</li>
	<li>The displayed power is the average of the instantaneous product of voltage and current.</li>
</ol>
<img alt="Digital multimeter measurement setup; voltage, current, resistance testing instrument; electronic analysis." src="/files/ftp_upload/10114/10114fig7.jpg" data-altupdatedat="1761830439000" data-alt="Figure 7"> 
Figure 7: Multimeter. <a href="//cloudfront.jove.com/files/ftp_upload/10114/10114fig7large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
8. Power supply
<ol>
	<li>Aside from the low power DC supply used in this procedure, there are other types of power supplies including a three-phase outlet (Fig. 8), a three-phase variable autotransformer (Fig. 9), and a higher power DC supply.</li>
	<li>The three-phase outlet provides three-phase voltages, typically at 208 V, 230 V, or 408 V in most electrical engineering laboratories. These voltages are equal in frequency and amplitude, and are 120° out phase from each other. Handling three-phase outlets requires special training and safety precautions.
	<ol>
		<li>In the US, 208 V, 230 V, and 480 V are common three-phase voltage levels in an educational lab environment that deals with power electronics and electric machines.</li>
	</ol>
	</li>
	<li>The three-phase variable auto-transformer (VARIAC) is an isolated transformer that provides a variable three-phase AC source from the three-phase outlet.</li>
	<li>Adjust the knob on the VARIAC where the VARIAC output can vary between 0% and 100% of the provided input voltage.</li>
	<li>A higher power DC supply provides higher DC voltage. Most low power DC supplies can provide up to 36 V and less than 10 A. High-power DC supplies can provide hundreds of volts and amps.
	<ol>
		<li>In an educational lab environment, a high-power DC supply provides DC voltage typically up to 400 V. They are common in power electronics applications because they emulate large battery packs in electric and hybrid vehicles, rectified household voltage, and other scenarios. They are also common in DC electric machine applications and inverter-based AC machines.</li>
	</ol>
	</li>
</ol>
<img alt="Electric circuit component with voltage marking, showing part of electronic equipment setup." src="/files/ftp_upload/10114/10114fig8.jpg" data-altupdatedat="1761830439000" data-alt="Figure 8"> 
Figure 8: Three-phase outlet. <a href="//cloudfront.jove.com/files/ftp_upload/10114/10114fig8large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Electrical circuit connection panel for power distribution system setup; labeled for input/output." src="/files/ftp_upload/10114/10114fig9.jpg" data-altupdatedat="1761830439000" data-alt="Figure 9"> 
Figure 9: Top view of a three-phase variable transformer (VARIAC). <a href="//cloudfront.jove.com/files/ftp_upload/10114/10114fig9large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Safety is the most important practice in an electrical engineering laboratory. Electrical measurement and power equipment are common in many heavy industries (metal processing, pulp and paper, etc.), automotive, marine, aerospace, military, and others. Various brands and models of different equipment and tools described in the video may have different labels, buttons, and knobs, but the general concepts still apply.
In an educational laboratory environment, the safety details and equipment des...

electrical safety precautions and basic equipment

Source: Ali Bazzi, Department of Electrical Engineering, University of Connecticut, Storrs, CT.
Electric machines and power electronics experiments involve electrical currents, voltages, power, and energy quantities that should be handled with extreme diligence and care. These may include three-phase AC voltage (208 V, 230 V, or 480 V), up to 250 V DC voltages, and currents that can reach 10 A. Electrocution occurs when an electrical path is established through the body with very low currents that can damage vital organs, such as a person&#8217;s heart, and may cause immediate death. All experiments must be performed in the presence of personnel trained to handle electricity at these voltage and current levels. In case of emergency, evacuate the lab through any of the exits and dial 911.

Source: Ali Bazzi, Department of Electrical Engineering, University of Connecticut, Storrs, CT.
Electric machines and power electronics experiments ...

The electricity that powers machines, tools, and other experimental apparatus must be handled with care and attention. Bodily contact with high voltage and current can cause muscular spasms, burns, cardiac arrest, and even death. Even small amounts of current passed through the body can cause electrocution. 10 milliamps can induce muscle contractions, loss of muscular control, and the inability to let go. 10 microamps through the heart can cause ventricular fibrillation. Laboratory experiments typically use equipment that complies with International Safety Standards. The Underwriters Laboratory UL label, for example, certifies that equipment meets these standards, which prevents certain types of hazardous exposure. However, electrical inputs and outputs, or customized equipment still pose a hazard. This video will present electrical safety precautions and introduce common electrical equipment used in many types of laboratory experiments.When using electrical equipment, wear long pants, closed-toe shoes, and appropriate personal protective equipment. Avoid loose clothing, and remove any dangling or metal accessories that can accidentally contact electricity. In the United States, single-phase AC power from a wall outlet is 120 Volts. Outlets for three-phase AC power can provide up to 480 volts and over 10 amps. So power sources must be handled with respect. A clean lab environment is important for mitigating hazards. Avoid loose or frayed wires, cables, and connections. Know how to turn off all equipment, power supplies, and circuit breakers. Make sure that at least two people work on an experiment that has accessible DC power greater than 50 volts. Use the same precautions with single-phase or three-phase AC mains power. Assume any exposed metal carries live electricity unless verified. Before changing a setup, turn off or unplug power sources used in the experiment. Proper grounding of equipment ensures the chassis is at earth-ground potential, which prevents electrical shock. Always plug equipment into AC outlets with the power cord intended for it. Equipment that is hotter than expected is both a hazard and a symptom of a problem that should be addressed. Finally, turn off all equipment after an experiment is finished, and turn off unused equipment before leaving the lab. Now that basic safety precautions have been presented, the operation of some common electrical equipment will be demonstrated in the laboratory.A function generator produces signals for other equipment needing an excitation or a drive voltage. The most common periodic outputs are sinusoidal, triangular, sawtooth, and square waves, which may be adjusted in amplitude, frequency, and DC offset. The output of the function generator is connected to the circuit or equipment using cables. Typically a BNC connector is used at one end, and alligator clips at the other end for easy connection to a circuit. A DC power supply provides voltage or a current to operate other electrical equipment. The adjustable output of a typical low-voltage laboratory supply ranges between 0 and 36 volts. Most single-output DC power supplies have three terminals: plus, minus, and ground. The plus terminal is connected to the higher voltage input of downstream equipment. The minus terminal is connected to the lower voltage input. The output is the voltage or current between the plus and minus terminals, which are electrically isolated from the ground. The ground terminal is a fixed earth-ground reference that is zero volts.Other common power sources include single-phase AC power from a standard wall outlet, or three-phase AC power. Single-phase power has one hot line and one neutral line for carrying current and delivers 120 volts. Three-phase power delivers higher voltages via three hot lines, with AC voltage on each line equal in frequency and magnitude, and 120 degrees out of phase from one another. The result can supply 208, 230, and 480 volts, with correspondingly greater power. Handling three-phase power requires special training and safety precautions.Next, a variable autotransformer, also known as a Variac, is used to either step up or down AC voltage. This is useful in applications requiring non-standard voltages or where the voltage must be varied. A knob varies the output voltage between zero and 100% of its maximum value. Note that the Variac does not provide electrical isolation, so avoid touching the output at any setting.An oscilloscope displays the voltages of time-varying signals, and is used to study the behavior of circuits. Oscilloscopes may have multiple channels, each displaying a single waveform. The two main types of probes used with this instrument are the conventional grounded probe and the differential probe.Here a regular grounded probe is connected to channel one. The grounded probe is usually rated to tolerate several hundred volts and measures voltage between the probe tip and its ground lead. The ground lead is tied to earth ground at the chassis of the oscilloscope. It is important to connect the ground lead only to a point in the circuit that is also grounded. Touching a ground lead to any other point will cause a short-circuit to ground. Now connect channel one of the oscilloscope to the output of the function generator, then turn it on. Adjust the time-scale of the oscilloscope with the seconds per division knob, and adjust the voltage scale with the volts per division knob. The trigger level is the voltage that a signal crosses to cause synchronization of the oscilloscope. Proper triggering minimizes noise in the display. Adjust the trigger knob to set the trigger level manually, or press set level to 50% to set it automatically.Finally, the multimeter is a versatile handheld, or bench-top instrument, for measuring voltage, current, resistance, and other electrical quantities. To measure voltage, insert the red probe into the contact labeled V Ohms and the black probe in the contact labeled COM for common. Turn on the DC power supply and set it to output 20 volts. Measure across the two output terminals by touching the red probe to the plus terminal and the black probe to the minus terminal. The multimeter reads 20 volts.Many experiments require the measurement of electrical quantities, and use basic instruments to provide this data. The study of polar dielectric liquid bridges requires a high-intensity electric field between two beakers of fluid. The beakers are initially in contact, and then are slowly pulled apart to form the bridge. In this application, a high-voltage DC power supply generates 1,500 volts, which requires great care for safe handling. To develop ways to control neural stem cell migration for therapeutic treatments, researchers studied their movement under the influence of an electric field. An experimental chamber used a DC power supply to generate the required controlled electric field. An ammeter measured the current and a multimeter measured the voltage across the test chamber, which was used to calculate electric field strength.You've just watched JoVE's introduction to electrical safety and basic electronic equipment. You should now understand how to work safely with electricity and how to use some basic electrical test equipment. Thanks for watching!

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safe handling of high-voltage lab power

Safe handling of high-voltage lab power is essential in electric machine and power electronics experiments. These labs involve electrical currents, voltages, power, and energy that require extreme care.

The systems used in this work can include three-phase AC voltage at 208 V, 230 V, or 480 V. They may also use up to 250 V DC and currents that can reach 10 A. These levels can be dangerous if handled without proper attention.

Electrocution can happen when electricity passes through the body. Even very low currents can create a path through the body and damage vital organs, including the heart. This can cause immediate death.

Because of these risks, experiments should be done only with personnel trained to handle electricity at these voltage and current levels. If an emergency occurs, evacuate the lab through any exit and dial 911.

Safe Handling of High-Voltage Lab Power

Safe handling of high-voltage lab power is essential in electric machine and power electronics experiments. These labs involve electrical currents, voltages, power, and energy that require extreme care. The systems used in this work can include three-phase AC voltage at 208 V, 230 V, or 480 V. They may also use up to 250 V DC and currents that can reach 10 A. These levels can be dangerous if handled without proper attention. Electrocution can happen when electricity passes through the body.

characterization of magnetic components

B-H Curves and Inductor Core Limits

Magnetic components such as inductors and transformers depend on the core material around their windings. In this experiment, students get hands-on experience with these parts from both a design view and a material view. The work focuses on B-H curves, which show the magnetic behavior of a material. A B-H curve describes the magnetic flux density the core can support as current flows through the windings. It also helps show the limit before magnetic saturation occurs. Magnetic saturation...

introduction to the power pole board

Power Pole Board for DC/DC Converter Labs

The HiRel Power Pole Board is a flexible tool for studying DC/DC converters. A DC/DC converter changes direct-current voltage and current from one level to another. In many cases, voltage conversion is the main goal. This board supports several converter types on one platform. It can be used to examine boost converters, which step voltage up, and buck converters, which step voltage down. It also helps students study buck-boost converters, which can step voltage up or down. The board is also...

dc/dc boost converter

Stepping Up DC Voltage with Boost Converters

DC voltage can be increased with a boost converter. This step-up circuit is useful in many applications where a DC source must be raised without first converting it to AC, using a transformer, and then rectifying the transformer output. A boost converter uses an inductor as an energy storage device. The inductor supports the output with extra energy in addition to the DC input source. That added energy raises the output voltage. This experiment studies several characteristics of a boost...

dc/dc buck converter

Buck Converter Step-Down DC Voltage

A DC/DC buck converter steps down DC voltage in an efficient, regulated way. Unlike transformers, which easily raise or lower AC voltage and current, DC systems need switching power converters to change voltage levels. The buck converter works by chopping the input DC voltage with a series input switch. An L-C low-pass filter then smooths the chopped signal and extracts the average output voltage. A diode gives the inductor current a path when the switch is off during part of the switching...

flyback converter

Flyback Converter Voltage Step-Up and Step-Down

A flyback converter is a buck-boost converter that can both step voltage up and step it down. It also provides electrical isolation between the input and the output by using a coupled inductor, or flyback transformer. The coupled inductor acts like a transformer with a turns ratio, but it also stores energy through the air gap. This setup gives the converter both voltage step-up and step-down capability. In the experiment, the converter is studied in open-loop operation with a manually set...

single phase transformers

Single Phase Transformer Testing

Single-phase transformers step up or step down AC voltage in electric power systems. They are stationary electric machines with primary and secondary coils, also called windings. The primary winding receives the applied voltage, and the secondary winding delivers the changed voltage. Inside the transformer, current in one winding creates magnetic flux in the core. This flux links the two windings and transfers energy between them. With AC current, the changing flux induces voltage in the...

single phase rectifiers

AC to DC Conversion with Rectifiers

Rectifiers convert AC power into DC power for electronic circuits. A DC power supply provides unidirectional voltage and current. Batteries can do this, but they are limited by lifetime and cost. Using a rectifier is another way to turn AC line power into DC power. A rectifier is a device that lets current pass in one direction and blocks it in the other. It works after a forward voltage threshold is reached. Rectifiers may use a diode, a silicon controlled rectifier, or other silicon P-N...

thyristor rectifier

Controlling SCR Half-Wave Rectification

Thyristors, also called silicon controlled rectifiers (SCRs), are used to control current in a rectifier circuit. Like diodes, they let current pass from the anode to the cathode and block current in the opposite direction. Unlike a diode, a thyristor can be turned on with a gate terminal that receives a small current pulse. A thyristor is a four-layer device with alternating n-type and p-type layers. These layers form a PNPN structure with three junctions. The device has three terminals. The...

single phase inverter

DC to AC Conversion with Half-Bridge Inverters

DC to AC conversion is the main idea behind a power inverter. DC power flows in one direction, while AC current changes direction at about 50-60 Hz. Many electronic devices are designed to run on AC power, so a DC source must be inverted before it can be used with them. An inverter makes this change through switching action. The switches repeatedly flip the polarity of the input DC source at the output, or load side, for part of a switching period. A typical power inverter needs a stable DC...

dc motors

DC Motors and Generator Action

DC machines use direct current and direct voltage to create motion or generate electricity. They were the first machines of this kind to be invented. A DC machine works with two magnetic fields that are controlled by DC currents, and the same machine can be set up as either a motor or a generator when the right field excitation is available. In a DC machine, the field is usually on the stator side and the armature is on the rotor side. That arrangement is the reverse of what is found in many...

ac induction motor characterization

Three-Phase Motor Equivalent Circuit Tests

Three-phase induction motor testing can be used to find equivalent circuit parameters. The experiment uses the per-phase equivalent circuit to model the motor. This model keeps the important behavior of the original system and makes calculations easier. The procedure uses tests similar to those used in transformer characterization. These measurements help estimate the motor's circuit values from its electrical response. The experiment also aims to operate the motor in the linear torque-speed...

vfd-fed ac induction machine

Variable Frequency Drive Speed Control

Variable frequency drives, or VFDs, control the speed of AC induction motors. They are a type of adjustable speed drive and are becoming standard equipment for powering most AC induction motors. In industrial and automation settings, VFDs can provide strong control of motor speed, torque, or position. This experiment focuses on speed control with open-loop operation. It uses constant voltage-to-frequency ratio control, also called V/f control. The motor usually operates at a rated stator flux,...

ac synchronous machine synchronization

Grid Connection of AC Synchronous Generators

AC synchronous generators are a major source of electrical power worldwide. They are three-phase, wound-rotor machines that are used in many power plants. These generators need a prime mover and an exciter to produce power. A prime mover is the device that spins the generator, often a turbine driven by fluid. That fluid can come from water flowing from a dam through a long nozzle or from steam made by burning coal. Most power plants use synchronous generators, including coal, nuclear, natural...

ac synchronous machine characterization

Three-Phase Synchronous Motor Starting and V-Curves

Three-phase synchronous motors and generators are important AC machines. Wound-rotor synchronous motors are less common than permanent magnet rotor synchronous motors because the rotor field uses brushes. Synchronous generators are much more common. They are used in most existing power plants because they provide excellent frequency and voltage regulation. A synchronous motor runs at the same speed as the stator magnetic field. This gives it almost 0% speed regulation, so the rotor speed stays...

electrical engineering

This collection starts with an electrical safety video that introduces the best practices for commonly used equipment in an electrical laboratory. Subsequent videos introduce elements such as inductors, transformers, convertors, rectifiers, and inverters.

Learn how high-voltage lab power is handled safely in electric machine and power electronics experiments, including AC and DC levels, current limits, and emergency response.

Safe Handling of High-Voltage Lab Power | JoVE K12

Texas Essential Knowledge and Skills

Physics

PHYS.1

PHYS.1.C

PHYS.2

PHYS.2.D

Chemistry and Physics

IPC.1

IPC.1.C

IPC.2

IPC.2.D

Ali Bazzi

Overview

Safety Principles

Basic Electrical Equipment

Applications

Summary

Characterization of Magnetic Components

Source: Ali Bazzi, Department of Electrical Engineering, University of Connecticut, Storrs, CT.
The objective of this experiment is to achieve hands-on ...

Magnetic Fields

Source: Yong P. Chen, PhD, Department of Physics &#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
Magnetic fields can be ...

A moving charge or a current creates a magnetic field in the surrounding space, in addition to its electric field. The magnetic field exerts a force on ...

Solenoids

A solenoid is a conducting wire coated with an insulating material, wound tightly in the form of a helical coil. The magnetic field for a solenoid is the ...

Induction

An emf is induced when the magnetic field in a coil is changed by pushing a bar magnet into or out of the coil. emfs of opposite signs are produced by ...

Faraday's Law

Faraday&#39;s law state that the induced emf is the negative change in the magnetic flux per unit of time. Any change in the magnetic field or change in ...

Lenz's Law

The direction in which the induced emf drives the current around a wire loop can be found through the negative sign. However, it is usually easier to ...

Electric Generator: Alternator

Electric generators induce an emf by rotating a coil in a magnetic field. A simple alternator is an AC generator that creates electrical energy that ...

Magnetic Field due to Moving Charges

A stationary charge creates and interacts with the electric field, while a moving charge creates a magnetic field.
Consider a point charge moving with a ...

Magnetic Field of a Solenoid

A solenoid is a conducting wire coated with an insulating material, wound tightly in the form of a helical coil. The magnetic field due to a solenoid is ...

Magnetic Flux

The magnetic flux measures the number of magnetic field lines passing through a given surface area. The SI unit for magnetic flux is the weber (Wb). ...

Magnetic Force

In addition to the electric forces between electric charges, moving electric charges exert magnetic forces on each other. A magnetic field is created by a ...

DC Generator

An alternator converts mechanical energy into electrical energy that varies sinusoidally, resulting in AC current. Meanwhile, a DC generator converts ...

Plan and carry out investigations to design, build, and refine a device that works within given constraints to demonstrate that an electric current can produce a magnetic field and that a changing magnetic field can produce an electric current.

Safe Handling of High-Voltage Lab Power

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