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What Is a Brushless Motor?

A brushless motor is a motor in which the commutator, brushes, and other mechanical contact parts have been removed. The commutator and brushes are eliminated by having an electronic circuit take the place of the commutator. In a DC motor, the magnetic force of the stator winding circuit drives the permanent magnet rotor. The current is switched by a sensor and a semiconductor switch to rotate the motor.

DC motors have the characteristics of DC motors in that the current is proportional to the torque and the voltage is proportional to the rotation speed, while the structure of AC motors incorporates the best features of both. A brushless motor is a compact, high-power, high-efficiency, and long-life motor that does not generate sparks or noise and is used in a wide range of applications, from computers to home appliances.

Uses of Brushless Motors

Brushless motors have DC motor characteristics and are characterized by high efficiency, long life, and low noise. They are widely used in home appliances, electronic devices, and automobiles. In-home appliances and brushless motors are used in fan motors and drive motors for air conditioners, dishwashers, washing machines, refrigerators, fans, vacuum cleaners, etc. They are ideal for compressors in inverter-controlled air conditioners and refrigerators.

Professional electronic equipment, they are widely used in paper feed for laser printers, propeller drive and gimbal control for drones, hard disks, and optical disks, and drive for drills, screwdrivers, and saws for tools. They are also used in vending machines, financial terminals, ticket-vending machines, copiers, water heaters, and refrigerated showcases.

In addition, adoption in the automotive field is rapidly increasing. Applications are expanding to include drive motors for electric power steering, door locks, headlight optical axis adjustment, door opening and closing, air conditioner compressors for electric vehicles, and traction motors for electric vehicles.

Principle of Brushless Motors

Brushless motors consist of a rotor and stator, a sensor to detect the rotor’s rotational position and a driver circuit to drive the motor.

1. Rotor and Stator

The rotor creates a magnetic field with a permanent magnet, and the stator generates a magnetic flux by winding the rotor. The direction of the magnetic flux is changed by changing the direction of the current flowing through the stator coils according to the rotation angle of the rotor. Brushless motors use sensors and semiconductor switches instead of commutators and brushes as a means of changing the direction of the magnetic flux.

2. Rotor Rotation Position Detection

Hall ICs or optical encoders are used as sensors to detect the rotational position of the rotor. Another method is to detect the back EMF. The rotor is rotated by detecting the position of the rotor and switching the current so that the direction of the magnetic flux in the stator advances sequentially. If the motor winding is 3-phase, three sensors are placed inside the stator and digital signals are output according to the rotation of the rotor.

3. Drive Driver

Brushless motors require an inverter circuit driver to control the motor as a power source. A switching transistor is connected to the motor winding, and six transistors make up the inverter. A diode bridge rectifies the commercial power supply to convert it to DC voltage, which is then supplied to the inverter circuit.

A digital signal from the rotor position detection sensor is input to the transistors in the inverter circuit, turning the inverter power supply ON and OFF. This power is supplied to the motor windings to drive the motor. The magnetic pole angle of the rotor is detected from a combination of signals from the sensors, and the transistors in the windings where torque is required are controlled to create a rotating magnetic field.

The rotational speed of the motor is fed back from the sensor signals to the control circuit so that a predetermined speed can be maintained.

Other Information on Brushless Motors

Features of Brushless Motors

1. Long Life
Brushless motors have long-life characteristics because they have no commutator, no brushes, and no sliding parts. They last 10 times longer than brush motors and are easier to maintain.

2. Motor Characteristics
The motor has the characteristics of a DC motor, with current proportional to torque and voltage proportional to rotational speed, and high torque can be obtained even at low speeds. It has the highest efficiency compared to other motors, and its small size and low noise make it suitable for a wide range of applications. High-speed rotation is also easy, and the noise generated is low.

3. Controllability
The small size, lightweight, and relatively small moment of inertia provide excellent controllability in response to changes. Even if the load changes, it can be operated at a stable speed from low to high.

4. Disadvantages
Requires an inverter circuit to control motor rotation as the motor’s power source. The cost of the entire device, including the control unit and rotation position sensor, is unfavorable.

What Is a Noise Generator?

A noise generator is a device that generates noise.

Noise generators are mainly used to evaluate the performance of various devices and systems. Some devices can generate white noise or pink noise, and some are available as a function within function generators.

White noise is noise that has uniform intensity across the entire bandwidth from low to high frequencies on the frequency axis. When heard audibly, it sounds like “sir”.

Pink noise is noise whose components become smaller as the frequency increases. When heard audibly, it sounds like a “thud”, like the sound of strong rain or a waterfall. Noise generators are useful as sound and vibration sources for sound and vibration testing.

Uses of Noise Generators

1. Evaluation of Electronic Equipment

There are two types of noise generators: dedicated noise generators and noise generators provided as a function within function generators. The purpose of using either type is to evaluate the functionality and performance of devices.

The noise generator is used to generate white noise or pink noise that simulates the noise that occurs in the natural world, and to evaluate whether the device under test can maintain the desired functions and performance.

It is used for EMI (Electro Magnetic Interference) testing and BER (Bit Error Rate) testing to evaluate whether the data errors in a device are within a specified range. It is also used for data transfer tests on disc drives of various BD/DVD recorders.

2. Acoustic and Vibration Tests

Noise generators are used as sound and vibration sources for sound and vibration testing. By connecting the output of white noise to a loudspeaker, the acoustic, sound insulation, and sound absorption characteristics of a hall, etc. can be evaluated. They are also useful for vibration tests when connected to a shaker.

Principle of Noise Generators

Noise can be generated by using a noise generator, by using an electronic circuit such as a diode, or by using a programming language.

1. Using a Noise Generator

Noise generators are used for electromagnetic interference (EMI) tests and acoustic characteristic tests, etc. Noise generators and function generators have built-in noise generators. Select white noise, pink noise, etc. to output noise. The noise generator that comes with the synthesizer can also be used.

2. Generate Noise With an Electronic Circuit Such as a Diode

Use the broadband noise generated when a reverse voltage is applied to a zener diode, transistor, or operational amplifier. This is white noise, but it can also be generated by temperature-controlled resistors or gas discharge tubes. Pink noise is generated by inversely proportional power attenuation of the white noise to the frequency.

3. Using Programming Languages

This method uses a programming language such as C, Java, or Python. Noise is generated by software using random numbers.

Types of Noise Generators

There are various types of noise generators. Some types output noise ranging from a few KHz to the GHz band, and their output frequency can be set linearly.

The level of noise output can also be adjusted. In addition to interfaces that can be operated via a control panel on the device itself, some types can be controlled from a PC via Ethernet.

Other Information on Noise Generators

EMI Testing

EMI testing evaluates whether a device can continue to function correctly when subjected to the worst-case noise that could occur in the user’s environment. For example, in the case of a household appliance like a television, it is permissible for the interference to momentarily disrupt the image on the screen or lead to audio malfunctions.

When the transient noise is eliminated, the device must be able to return to its original state. In order to confirm such a situation, a noise generator is used to create a worst-case environmental condition and evaluate whether normal operation can be continued under such conditions.

What Is a Ceramic Capacitor?

A ceramic capacitor is a capacitor that uses ceramic as the derivative.

The capacitor consists of two metal plates and a derivative sandwiched between the metal plates. Several materials are used As a derivative of the capacitor, each with its own characteristics.

Ceramic capacitors are characterized by their high dielectric constant, small size, and heat resistance. Furthermore, as capacitors with good frequency characteristics, they are often used in high-frequency circuits.

Uses of Ceramic Capacitors

Ceramic capacitors are used as bypass capacitors in digital circuits. A capacitor is characterized by its ability to pass AC current but not DC current.

Ceramic capacitors are used as coupling capacitors or line filters because of their ceramic properties. Examples include AC/DC and DC/DC converter circuits and circuits for circuit breakers.

They are also widely used to cancel high and low frequency noise.

Principle of Ceramic Capacitors

The principle of a ceramic capacitor is the same as that of a general capacitor. In principle, a ceramic dielectric is placed between two electrodes, and when a voltage is generated between the electrodes, electric charge is stored in the electrodes. Thereafter, the stored electric charge is released as charge by the capacitor.

The capacity of the charge stored by a capacitor is called capacitance. The capacitance and its properties vary depending on the material of the dielectric, the distance between the electrodes, and the number of dielectric layers.

Ceramic derivatives with high inductivity are used. The main materials used are titanium dioxide and alumina. Barium titanate is also used, but it is slightly more expensive. Although expensive, Barium titanate capacitors have higher capacitance.

Types of Ceramic Capacitors

Ceramic capacitors are classified into three main types, namely: low dielectric constant type, high dielectric constant type, and semiconductor type.

1. Low Dielectric Constant Type

Titanium dioxide is used as the main dielectric. It is resistant to temperature change, used for coupling and for temperature compensation.

2. High Dielectric Constant Type

Barium titanate is used as the dielectric, and its dielectric constant is higher than that of titanium dioxide. It has a high capacitance and is used for smoothing circuits. However, it is somewhat expensive.

3. Semiconductor Type

Semiconductor type uses semiconductor ceramics such as strontium titanate as the dielectric. It is considered a compact capacitor with large capacitance and good insulation properties. It is the most expensive of the three.

Other Information on Ceramic Capacitors

1. How to Read Ceramic Capacitor Capacitance

Ceramic capacitors do not directly state their capacitance such as “0.1 uF” or “10 uF” due to their small body size, but only use 1 to 3 digits to indicate the capacitance.

In the Case of 1 to 2 Digits
In the case of 1- to 2-digit numbers, the capacitance is simply the number read as it is and the unit of “pF (picoFarad)” is added. For example, “5” is 5pF and “33” is 33pF.

The smaller the number, the smaller will be the capacitance, while the smaller the capacitor, the smaller the size of the body.

In the case of 3 digits
In the case of 3-digit capacitors, as with carbon film resistors, the upper two digits are read as numerical values, while the third digit is multiplied as a multiplier. The unit is also “pF”. For example, “104” is 10 x 10 to the 4th power = 100000pF = 100nF = 0.1uF, and “223” is 22 x 10 to the 3rd power = 22000pF = 22nF = 0.022uF.

On the other hand, many chip-type ceramic capacitors do not indicate the capacitance on the body. It is recommended to check the capacitance with a tester capable of measuring capacitance before mounting or replacing parts, such as removing the capacitor from the tape just before use or storing it in a case that can be divided into smaller pieces.

2. Polarity of Ceramic Capacitors

In general, ceramic capacitors have no polarity and can be mounted in either direction in a circuit. In the case of leaded components, since the capacitance is printed on only one side, the sides with the capacitance printed on them should basically face the same direction.

If there are taller components nearby, mount them in an orientation that allows the values to be read later, so that the board is easy to see when checking.

3. Withstand Voltage of Ceramic Capacitor

Ceramic capacitors have an upper limit for the voltage that can be applied. However, depending on the size and rating of the capacitor itself, it may not be specified on the body or may be specified as an abbreviation.

When using capacitors in circuits that handle particularly high voltages, please check the data sheet or manufacturer’s model number carefully. This is because the manufacturer’s model number, which is a long list of alphanumeric characters, may contain information on withstand voltage.

What Is a Flexible Cable?

A flexible cable is a wire that is laid flat and coated with insulation.

The acronym for flexible cable is FFC. Ordinary wires are made by gathering wires with a circular Cross-section through an insulation layer and coating them so the cross section is round. FFC, on the other hand, is made by lining up flat wires and sandwiching them between resin films that serve as the insulation layer, and is characterized by its flat shape and much thinner thickness compared to ordinary wires.

Uses of Flexible Cables

Flexible cables are widely used as space-saving electric wires because they can be bent. In recent years, flexible cables have been manufactured in response to the trend toward downsizing, weight reduction, and space saving in various types of equipment.

Flexible cables can be used to connect printed circuit boards to circuit boards, as well as to circuit boards and electronic components. Because they are relatively inexpensive and can be bent repeatedly, they are often used where they operate. Examples include home appliances in general, LCD TVs, oil fan heaters, printers and copiers, stereos, VCRs, and telephones.

Flexible cables are available in many variations, including those with many cores, with double-sided tape, halogen-free, and gold-plated.

Principle of Flexible Cables

A flat wire is sandwiched between two pieces of insulating plastic film, with adhesive applied to the joint surfaces, while heat and pressure are applied to the adhesive. By crimping, the thickness of the flexible cable can be made very thin, such as 0.3 mm. Tin-plated copper foil is mainly used for wires, but nickel-plated copper and gold-plated copper are also used.

Polyethylene terephthalate (PET) and polyimide are commonly used as plastic films for insulation. Adhesives such as polyester-based materials are used. Most of the flexible cables have an upper limit of use temperature of about 75°C, which is not very high, but there are flexible flat cables with high heat resistance that have an upper limit of use of about 125°C, depending on the material.

The ends of flexible cables are reinforced with reinforcing plates made of polyester film, etc., and can be connected to connectors. Specific structures include one in which the conductor is exposed at both ends and supported by a reinforcing plate, one in which the conductor is supported by a reinforcing plate with the exposed sides reversed, And the one in which only one end is supported by a reinforcing plate. Some cables have reinforcing plates that are shaped in such a way as to improve the performance of connector insertion.

Hot melt adhesive is used to bond the flexible cable to the reinforcement plate. When used at high temperatures (150°C) while mated to the connector, the adhesive may soften thereby making the connection unstable. There are reports that polyester-based adhesives have been developed to solve this problem.

Flexible Cables and Other Information

Flexible Cable Standards

Most flexible cable products meet UL standards, which are product safety standards established by Underwriters Laboratories Inc. Most flexible cables are UL Listed, a product safety standard established by Underwriters Laboratories Inc.

The markings on the product itself might indicate that the product is UL Listed. FFC products are designed to comply with UL styles, which have specific ratings (temperature and voltage) and flame-retardant ratings. All FFC products have passed the most stringent vertical Flame-retardant test (VW-1).

In addition, some applications may require CSA certification, which is the Canadian safety standard for electrical products such as machine tools, electronic equipment, and medical equipment, and is designed to ensure the safety of human life and property.

What Is a Modular Jack?

A modular jack is a connector used for connection.

It can be detached with a single touch and is often used as a connector for interfaces. Also called modular jacks or modular plugs, they are connected to modular cables. It can be used for telephone lines, ADSL communication, and LAN lines.

Due to their superior characteristics, they are widely used in a variety of industries and application areas.

Uses of Modular Jacks

Modular jacks are used to connect lines for interfaces. Available as a square exposed type or embedded as a panel in a wall, they are a connection tool with numerous uses. The size, shape, and performance vary depending on the standard, so it is required to use the right one for the application.

1. Telecommunication Equipment

Modular jacks play an important role in telecommunications equipment. In particular, they are used to connect Ethernet cables in networking equipment such as modems and routers. This enables high-speed data transmission.

2. Computers

Modular jacks are also frequently used in computer equipment such as PCs and servers. For example, they are used to connect USB ports and monitors to transfer data and display screens.

3. Household Appliances

Modular jacks also have a very large number of applications in household appliances. For example, they are used to connect all kinds of electrical appliances such as telephones, home game consoles, and televisions.

4. Automotive Industry

Modular jacks also play an important role in the automotive industry. They are used to connect various electronic devices, sensors, control units, and other devices in the car to improve the functionality and performance of the vehicle. They are also used for in-vehicle communication and entertainment systems.

Principle of Modular Jacks

Modular jacks are made of flame-retardant plastic. Signal lines are drawn inside, and the wires are color-coded for the number of poles in each standard.

Consisting of multiple pins and corresponding sockets, modular jacks typically consist of eight metal pins and sockets with eight corresponding holes. This allows the male plug to hook onto the female one with a claw at the top of the plug, which clicks into place when connected and cannot be pulled out immediately. To pull it out, push the claw down and pull it out.

There are several standards for modular jacks. The 6-pole, 2-prong connector with 6 terminals is commonly known as RJ-11, and the 8-pole, 8-prong connector with 8 terminals is known as RJ-45, mainly used for LAN. The wiring of 8-pole, 8-conductor for LAN generally follows T568A or T568B of the American National Standards Institute.

Some connectors allow multiple phone lines or LAN connections with a single modular jack. Special tools are required to replace modular jacks.

Characteristics of Modular Jacks

Modular jacks are characterized by their ease of removal and connection. Since the pins and sockets engage securely, there is little signal loss or contact failure, providing a highly reliable connection. In addition, the connector locks automatically when inserted, preventing accidental disconnection.

Because modular jacks are standardized, they are also highly compatible between different devices and systems. This is useful when different devices need to be combined in various industries and applications. For example, modular jacks are used in a wide variety of equipment such as televisions, telephones, and computers, and are a common standard to ensure compatibility.

Furthermore, by combining pins and sockets, multiple signals can be connected at once, thus contributing to more efficient wiring. This not only reduces wiring complexity and enables efficient wiring design, but also makes it easy to accommodate different signals and protocols by changing connector shapes and sizes.

What Is a Tantalum Capacitor?

A tantalum capacitor is a type of electrolytic capacitor that uses tantalum oxide as the Dielectric material.

An electrolytic capacitor is a capacitor that uses an oxide film of aluminum or tantalum as a dielectric material. Tantalum capacitors are made by oxidizing the surface of tantalum, a rare metal, to form tantalum pentoxide (Ta2O5), which is then used as the Dielectric material.

Tantalum capacitors are smaller than aluminum electrolytic capacitors. In terms of merits, tantalum capacitors have a longer life, are resistant to temperature changes, and have better frequency characteristics. On the other hand, tantalum capacitor is very expensive, so the price is relatively high for a capacitor.

In addition, there is a risk of short circuit between electrodes when broken. Therefore, it is important to observe proper usage.

Uses of Tantalum Capacitors

Tantalum capacitors have a wide range of applications and are used in all kinds of electronic equipment, including cellular phones, personal computers, video game consoles, car navigation systems, and audio equipment. Because of their superior high-frequency and temperature characteristics compared to aluminum capacitors, tantalum capacitors are used in smoothing circuits for switching power supplies that turn current on and off at high frequencies.

Another ideal application is decoupling capacitors that absorb spike noise in power supply circuits. Furthermore, they are also used as backup capacitors to hold the power supply temporarily.

In recent years, miniaturization has been progressing, and products as small as 0.5 mm in height have appeared, contributing to the miniaturization of cell phones, personal computers, and other devices.

Principle of Tantalum Capacitor

A tantalum capacitor is composed of a chant pole, a dielectric, and a cathode.

1. Anode

Tantalum material is connected to the electrode via a sintered metal rod.

2. Dielectric

A thin film of tantalum pentoxide, which is oxidized from the tantalum of the anode, serves as the dielectric. A kind of diode is formed between the tantalum pentoxide and the cathode, which has capacitance when the reverse bias is maintained, but large current flow when a forward voltage is applied.

This is the reason why tantalum capacitors have polarity. The extremely thin layer of tantalum pentoxide allows for a large capacitance.

3. Cathode

Manganese dioxide or a conductive polymer is used as the cathode material to ensure continuity between the electrodes. Conductive polymers have lower resistance and better ESR characteristics than manganese dioxide.

In addition, a current-carrying metal such as silver or graphite is placed between the cathode and the electrode to lower the resistance. Aluminum electrolytic capacitors use an electrolytic solution, which gradually evaporates and has a relatively short life span. Tantalum capacitors, on the other hand, are made entirely of solid material and have a long life span.

Other Information on Tantalum Capacitors

1. Precautions for Use

The main cause of failure in tantalum capacitors is due to a localized short circuit in the dielectric of the capacitor. When connected to a low impedance circuit such as a power line, a large current will concentrate at the shorted point and generate heat, which may lead to ignition.

Once a tantalum capacitor ignites, it continues to burn with a flame Until it burns out. For this reason, many manufacturers of equipment requiring high reliability or equipment that is constantly energized, have banned the use of tantalum capacitors altogether. Even in portable equipment powered by batteries, burnout of tantalum capacitors has been reported, so care and circuit verification are required when using them.

Two general countermeasures are “do not apply reverse voltage under any circumstances” and “select a capacitor with a rated voltage that has a sufficient margin for the voltage applied to the capacitor.” In particular, when used in a power supply circuit, it is desirable to use a tantalum capacitor with a voltage rating of at least twice the power supply voltage, or three times the voltage rating, if possible.

In addition, if the ripple current inflow is large, the heat generated inside the capacitor may cause degradation, so it is also recommended to select a large package that is conducive for heat dissipation.

2. Polarity Indication of Tantalum Capacitor

Tantalum capacitors are polarized, and if the specified polarity is incorrect, a large current will flow, leading to ignition in the worst case. Therefore, it is necessary to understand the polarity markings on the electrodes.

Tantalum capacitors can be classified into three types based on their construction, namely: chip type, metal case hermetically sealed type, and resin dipped type.

• Chip Type
  A white band is printed on the top surface of the black molded case with the capacitance and rated voltage, while the electrode below the band is the anode.
• Metal Case Hermetic Seal Type
  For applications requiring high reliability, a + sign is printed on the surface of the round cylindrical shape, along with capacitance, rated voltage, etc. The lead wire on the side near the + sign is the anode while the lead wire on the side near the – sign is the cathode.
• Resin Dip Type
  It is vertically structured. The + sign is printed on the resin surface along with capacitance, rated voltage, etc. The lead wire on the side near the + sign is the anode while the lead wire on the side near the – sign is the cathode. The lead wires are unequal in length, with the lead wire on the cathode side being shorter.

Aluminum electrolytic capacitors, which are also polarized, are marked on the anode side and are marked differently from tantalum capacitors. When replacing an aluminum electrolytic capacitor with a tantalum capacitor, care must be taken to ensure that the polarity is correct.

What Is a Current Transformer?

A current transformer (CT) is a device that transforms a magnitude of current, often abbreviated as CT.

The magnitude of the current input to the current transformer is transformed according to the ratio of the number of Coils or turns at the input and output. It is used to convert the current of a large-current circuit or a high-voltage circuit into a small current. Also, it is used for current measurement and relays.

Uses of Current Transformers

Current transformers are widely used in industry and infrastructure equipment.

The following are examples of current transformer applications:

• Current monitoring of pumps for pumping water
• Monitoring of falling water in wastewater and sewage treatment pumps
• Monitoring of current at the destination of power transmission in substations
• Monitoring of the amount of electricity generated at power plants

Current transformers are used for circuit insulation and current conversion. Circuit isolation is used to isolate the main circuit from the control circuit where large current flows, and Current Transformers are also used to monitor the current of small pumps (5 A or so) for the purpose of circuit isolation.

Current transformers are used to output large currents as small current circuits. Since it is uneconomical to introduce several thousand A of current into the control circuit due to the large size of the control wiring, Current Transformers are used to transform the current to a maximum of about 5 A for control and monitoring.

Current Transformer Principle

Current transformers for AC consist of an iron core, a primary coil, and a secondary coil. Each of these is wound around an iron core.

When current flows through the primary coil, a magnetic flux is generated in the iron core to excite the secondary coil. The secondary coil generates a current on the secondary side according to the magnitude of the magnetic flux excited.

The current value generated in the secondary coil is determined by the current in the primary coil and the turn ratio: the more turns in the primary coil, the higher the current value, and the less turns in the secondary coil, the lower the current value. Generally, the current value of the secondary coil is adjusted to 1 A or 5 A for the maximum allowable current in the primary coil.

Types of Current Transformers

Current transformers are classified into wire-wound current transformers and feed-through current transformers. The following are examples of Current Transformer types:

1. Current Transformer

Current transformers consist of an annular iron core and input/output coils.

It works as described in the principle section. It is mainly used for small current transformers of several A to several tens of A, because the larger the current in the measurement circuit, the larger the allowable wiring current on the primary side. It is characterized by its ability to measure small currents with high accuracy.

2. Through-Hole Type Current Transformer

Current transformers are transformers that do away with the primary-side coil. The circuit wiring to be measured is inserted between the iron core and the primary coil.

Current transformers are generally selected for large current circuits ranging from several tens of A to several hundred A or more, and can be installed at low-cost since there is no primary-side coil.

3. DC Current Transformer

Current transformers for AC circuits are described in the principle section. It cannot be used for DC circuits because no magnetic flux is generated in the iron core. A DC current transformer using a Hall element is used to measure DC current.

When a magnetic field is applied to a circuit in which Current flow, a voltage corresponding to the current value is generated. This is called the Hall effect, and a Hall element is an element that outputs a voltage based on this principle. Most DC Current Transformers are current transformers using Hall elements.

However, in the case of direct current, there are high current power supplies, such as for trams. Their current values may be tens of thousands of A, which is difficult to measure with a Hall element Current Transformer. 

4. Shunt Resistor Type Current Divider

A shunt resistor is a low-resistance resistor for measuring current. Since the resistance value is predetermined, it can be converted to a current value by measuring the voltage at both ends.

Shunt resistors are used to measure large DC currents of several tens of thousands of A. Since shunt resistors in high current circuits generate a large amount of heat, they are often water-cooled.

How to Select a Current Transformer

Current transformers are basically selected according to the value of the current flowing on the primary side, and a current transformer with a current specification larger than the maximum current flowing in the primary side should be selected.

Current transformers are connected to an overcurrent relay or current indicator on the secondary side. Depending on the intended application, it is recommended to select a current transformer with a secondary side current value of 0-1A or 0-5A,

Since the overcurrent relay is often placed close to the current transformer, a product with a secondary side current specification of 0-5 A is often selected for the current transformer. This is because 0-5A makes it possible to measure current values more precisely.

On the other hand, a current indicator may be separated from a current transformer, in which case the secondary side current specification is often set to 0-1A. This is because the 0-1A specification makes it possible to reduce the power supply capacity required for the current transformer.

What Is a Radio Frequency Identification (RFID) System?

A radio frequency identification (RFID) system is a system that uses radio waves or electromagnetic waves to recognize information in RFID tags, or smart labels attached to products and to read and write data.

Advantages of the radio frequency identification (RFID) System include the ability to read multiple tags at the same time from remote locations, easy data modification, and the ability to read dirty tags. Other systems that recognize information include barcodes, but RFID systems can also be used in situations where barcodes cannot be used.

Uses of the Radio Frequency Identification (RFID) System

Radio frequency identification (RFID) Systems are often used in manufacturing process and logistics because they allow a sequence of events to be monitored. During manufacturing of products in factory, consistency in product quality is important.However, different lots of raw materials or different workers often produce different quality.

By introducing RFID, it is possible to link the conditions of creation and quality with data, which can be useful when problems arise. In logistics, RFID is used for inspection of incoming goods. Although the contents of an incoming product may not be visible depending on the state of its packaging, RFID makes it possible to inspect the product at once, even if the contents are not visible.

Principle of Radio Frequency Identification (RFID) System

Radio frequency identification (RFID) system consists of a reader/writer, RFID tags, and data processing equipment.

1. Reader/Writer

First, the reader/writer transmits radio or electromagnetic waves with information to the transmitting RFID tag, which receives the information and processes it using the power generated in the tag, which in turn transmits radio or electromagnetic waves with information from the tag. The reader/writer reads the information and transmits it to the data processing equipment.

2. RF Tag

RF tags contain an antenna and a microchip that enables contactless reading and writing of the information stored in the tag. RF tags vary in size and shape from small and inexpensive to larger tags with more sophisticated functions.

3. Data Processing Equipment

Data processing equipment includes PCs, machine automation controllers, and antenna coolers. Antenna coolers function to prevent RFID antennas from overheating, allowing them to be used for extended periods of time.

RFID is classified according to the frequency of the radio, or electromagnetic waves used. Higher frequencies result in faster information transmission. On the other hand, lower frequencies can transmit information stably over a longer distance.

Since each has different characteristics, it is important to use different frequencies for different purposes. In recent years, as in the case of 5G, the speed of information transmission has been emphasized, with high-frequency band being the most widely used.

Other Information on Radio Frequency Identification (RFID) Systems

1. Precautions When Using RFID

Radio frequency identification (RFID) systems use radio waves and electromagnetic waves, so the following precautions should be taken.

Keep Them Away From Metal.
Especially in the high-frequency band, radio and electromagnetic waves can generate heat in metals. Hence, it is preferable to keep them away from metal because of possible adverse effects from heat.

Do Not Stack RFID Tags on Top of Each Other.
If tags overlap each other, they may interfere with each other and cannot be read correctly.

Do Not Place RFID Tags Too Far From the Reader.
If RFID tags and readers are too far apart, reading accuracy will decrease and quality will suffer. It is necessary to install them at an appropriate distance.

Adjust the Frequency Band.
Radio frequency identification (RFID) systems have different frequency bands and protocols, which can cause compatibility issues. Standardizing frequency bands will facilitate data exchange between different systems.

2. Examples of Radio Frequency Identification (RFID) System Applications

Application in the Retail Industry
A leading Japanese apparel brand has introduced a radio frequency identification (RFID) system (RFID tags) in all of its 2,000 brand stores, both inside and outside the company’s stores. The initial implementation cost is said to be in the tens of billions of dollars, but the cost-effectiveness of the system is said to be tremendous because of the multiple benefits gained, such as reduced inventory management time, reduced waiting time for checkout, and reduced number of missing items.

Use at Events
Radio frequency identification (RFID) system can be used to prevent long lines in front of stores and sales at events. Further, by distributing tickets and wristbands with RFID tags in advance, it is possible to reduce the lines and prevent lost purchase opportunities.

What Is a Freight & Passenger Elevator?

Freight & passenger elevators are devices used to move people and cargo vertically or diagonally.

Freight & passenger elevators are generally used for vertical movement, although those that move horizontally may also be called freight & passenger elevators. Those that do not carry people, but only elevate and transport cargo, are sometimes called lifts.

Those that move vertically with people on board are called elevators if they are box-shaped, and it is easy to imagine escalators if they are stairway-type. Today, freight & passenger elevators can be seen in many aspects of daily life.

Uses of Freight & Passenger Elevators

Freight & passenger elevators is a general term for devices that carry people or loads and move them vertically, diagonally, or horizontally. Those that use hydraulic jacks to move loads are called hand lifts, and are used as mobile trolleys.

Motorized, box-shaped freight & passenger elevators are called “elevators,” and they range from those used exclusively for luggage to those that allow people to get in and out of the elevator. Freight & passenger elevators are used as forklifts. They are also used in the broad sense of the term, for example, gas cylinders used to change the height of office chairs.

Principle of Freight & Passenger Elevator

Freight & passenger elevator mechanisms for vertical movement include those using gears, electric actuators, hydraulic jacks, gas springs, and others, depending on the size, object, and amount of movement. The simplest and most familiar lifting mechanism is by pulley. In this case, a balancing weight and a dynamic pulley are used to lighten the load, thereby reducing size and energy consumption.

Freight & passenger elevators, such as elevators, which do not move themselves but repeatedly go up and down on the spot, are available in mechanical and electric types. Freight & passenger elevators that are moved to a different location, such as hand lifts and forklifts, are often mechanical types, and incase of electric types, built-in batteries are used.

Freight & passenger elevators are also equipped with safety devices to prevent free fall in the event of a malfunction. This is always necessary to minimize human and property damage in the event of a malfunction. 

Types of Freight & Passenger Elevators

Typical types of freight & passenger elevators are as follows:

1. Elevator

Elevators are used to move people and cargo. Freight & passenger elevators are installed in a wide range of buildings, including high-rise buildings and condominiums, and are indispensable to our daily lives. There are two types: one is suspended by main cables or chains, and the other is driven by hydraulic jacks.

2. Step Height Eliminator

Steps eliminators are used in places where there are steps. The table base moves up and down according to the difference in the steps, allowing easy movement in and out of entrances and on steps in buildings. It is also useful in narrow places where a ramp cannot be installed. 

3. Chair-Type Freight & Passenger Elevator

A chair-type stairway freight & passenger elevator helps people to go up and down stairs. They can be installed in any stairway in public facilities or private homes, and help the elderly or those with disabilities. There are two types: chair-type and wheelchair-type, which are selected according to the user’s level of assistance.

4. Escalator

An escalator, also called a moving staircase, is a device in which the treads are continuously raised and lowered by power. Moving at a speed of about 1.8 km/h, it can be used by 9,000 people per hour when two people ride on each step. They are installed in locations where many people are moving. 

5. Dedicated Baggage Freight & Passenger Elevator

A dedicated small baggage freight & passenger elevator is an elevator that is designed for the exclusive use of luggage. Freight & passenger elevators are relatively inexpensive to install because they are designed to carry relatively small items and have relaxed safety standards for strength, etc. They are used in a wide variety of workplaces where luggage is transported, and contribute not only to functionality and safety, but also to reducing environmental impact.

Other Information on Freight & Passenger Elevators

1. Price of Freight & Passenger Elevators

Freight & passenger elevator prices vary widely depending on size, structure, and function. However, the price increases as the number of functions increases, such as a type that can run in addition to lifting and lowering or an electric type, even if it is small.

Freight & passenger elevators are relatively expensive due to the installation cost. 

Freight & passenger elevators also include stairway elevators used in nursing and medical facilities. They elevators are installed on rails at the ends of staircases, and users can go up and down the staircases by sitting on a chair installed on the rails.

They in a wide variety of types and uses, so the price varies greatly depending on the purpose. The price also varies depending on the functions one chooses, so it is important to select the functions one really need. 

2. Rental of Freight & Passenger Elevator

Freight & passenger elevators can be very expensive, depending on their functions. For this reason, many companies offer freight & passenger elevators for rent. As with purchases, installation takes one day, and it is possible to consult with the customer about the possibility of installation prior to installation. In general, there are many stair freight & passenger elevators available for rent. They fulfill the need for freight & passenger elevators but do not want to purchase them, such as in the case of families with elderly people, or when an injury makes it difficult to go up and down stairs.

What Is Sputtering Equipment?

Sputtering equipment is a device that performs sputtering to create a very thin film uniformly on the surface of an object.

Sputtering is a physical vapor deposition (PVD) method, like vacuum evaporation and ion plating. Sputtering is used in various fields, including the deposition of semiconductor and liquid crystal films. It is also used to clean the surface of objects.

Uses of Sputtering Equipment

Sputtering equipment is used to fabricate thin films for semiconductors, liquid crystals, and plasma displays. Compared to other PVD evaporation systems, sputtering equipment is capable of depositing metals and alloys with high melting points, and thus has a wide range of applications.

Recently, metals have been deposited on the surface of plastic, glass, and film to make them conductive and used as transparent electrodes and wiring for touch panels. This, further expands the range of applications for sputtering equipment.

In addition, medical devices and miscellaneous goods with antibacterial properties coated with photocatalytic titanium dioxide on their surfaces are also available. It is also used in analytical applications, such as sample preparation for scanning electron microscopes (SEM).

Structure of Sputtering Equipment

Sputtering equipment mainly consists of the following components:

• Vacuum chamber
• Sample stand
• Sputtering target
• Exhaust system (rotary pump, etc.)
• Gas supply system
• Power supply (high frequency, High-voltage power supply, etc.)

The vacuum chamber contains a sample stand that holds the substrate and a sputtering target that supplies the sputtering material, while the vacuum pump and gas supply system are connected to the chamber.

Principle of Sputtering Equipment

The principle of sputtering equipment is to deposit a film on the surface of an object by applying high voltage under vacuum and repelling the atoms of the film material. First, the chamber is sufficiently depressurized by a pump, and then inert gases such as argon are filled into the equipment at a constant pressure.

When a high negative voltage is applied to the target, which is the material for the thin film, and a glow discharge is generated, the argon filled in the equipment becomes plasma and collides with the target on the cathode, causing the Ions, atoms and molecules on the target to be ejected. The target atoms are then deposited on the surface of the target to which the positive voltage is applied, resulting in the production of a thin film.

Types of Sputtering Equipment

There are various types of sputtering methods.

1. DC Method

This method applies DC voltage between electrodes. This method has various advantages, such as a simple structure. However, the disadvantages include the possibility that the sample may be damaged by the high-temperature plasma and the inability to form a film properly if the sputtering target is an insulator.

2. RF Method

This method applies a high-frequency AC voltage between electrodes to form films on materials such as ceramics, silica and other oxides, metal oxides, and nitrides, which cannot be formed by the DC method.

3. Magnetron Method

This method uses a magnet to create a magnetic field on the target side to keep the plasma near the target. This not only reduces damage to the sample caused by the plasma, but also increases the plasma generation speed, resulting in faster film formation. Various power supply methods are available, including DC, AC, and high-frequency AC. On the other hand, the target is reduced unevenly and the utilization efficiency tends to be low. 

4. Ion beam Method

Ions are produced at a separate location from the target or sample and accelerated to the target. Since there is no discharge in the chamber, the effect on the sample is minimized and there is no need to consider the adhesion of impurities or the conductivity of the target.

In addition to the above, there are various types of sputtering equipment, such as Electron Cyclotron (ECR), which should be selected appropriately according to the application and budget.

Other Information on Sputtering Equipment

Features of Sputtering Equipment

Sputtering equipment can make the film thickness uniform, and since it uses electrical properties, it can increase the strength of the film. It can produce films of high-melting-point metals and alloy materials, which is difficult with other PVD methods. Another method is to fill oxygen instead of argon or other inert gases to deposit oxide films.

However, there are some disadvantages, such as the longer time required for film deposition compared to other PVD methods and the risk of damaging the sputtering target by the generated plasma.