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Cause of damage of parallel power capacitor

• When cutting off the capacitor bank, restriking overvoltage caused by breaker restrike leads to the insulation damage or breakdown between capacitors. Some capacitor banks don’t have any overvoltage protection measures nor series reactor, particularly, the frequently operated capacitors easily lead to insulation damage or even explosion.
• Too large current over the capacitor and overcurrent caused by overcurrent harmonics in power grid make the capacitor overheated, insulation reduction or even damage.
• The capacitor is not equipped with a single fuse or the fuse characteristics (characteristic aegis of ampere second) are too poor. When the internal components of the capacitor are seriously breakdown and the fault current is generated, the fuse can't fuse in time. Meanwhile, effective protective relaying measures fail to keep up, overcurrent leads to a sharp rise in the temperature inside the capacitor and thereof leads to capacitor expansion or explosion.
• Poor product quality. The paper oil insulation fails to be dried or dipping treatment under a strict vacuum condition, the residual bubbles inside produce partial discharge under the long-term working voltage, while partial discharge further leads to insulation damage and aging. As a result, the temperature also rises, which eventually leads to electrochemical breakdown of components and the capacitor damages.

When a new system is used for the first time or the meter, sensor is replaced, calibration must be made before use.
There are two kinds of calibration in general, one is the physical calibration (in this mode, two points needs to be calibrated, namely the zero position and the range), and another is the digital calibration.

Physical calibration is applicable for most weighing systems, and digital calibration is used in the fields when the physical demarcation can't be used. However, digital calibration can't eliminate the errors, its accuracy is related with the sensor’s sensitivity, range and wiring system (four-wire or six-wire), the division value or maximum range setting, as well as the signal loss on the junction box and cable.
The scale division and maximum range shall be set before calibration.
Before calibration, the instrument shall be powered on for at least 15 minutes until the sensors and meters reach the thermal equilibrium state.

1. Device lifetime
In the broad sense, the inverter is a Switching Mode Power Supply, so its components can be basically divided into resistor, capacity, diode power devices (IGBT or MOS tubes), inductor and transformer, current sensor, IC, optocoupler and relay.
Generally, service life of the resistor, chip capacitor and ceramic capacitor can be more than20 years. Theoretically, the inductor and transformer are defaulted to work for long time without failure on the design if only not exceeding the material temperature. Diodes and triodes with small power can work more than 100 thousand hours basically; The mechanical life of the relay is generally more than 1 million times and the electrical life is more than 10 thousand times; Generally, power device IGBT or MOS do not consider the life as long as they meet design specifications. The fan and fuse are vulnerable components, they will not affect the service life of the inverter, and they can be replaced as long as they break; service life of the film capacitor is more than 100 thousand hours and that of electrolytic capacitor is 2000-3000H at 105℃, the service life may also be 5000-6000H, and it doubles as the temperature decreases 10℃. Therefore, the weakest device of the inverter lies in the service life of the electrolytic capacitor.

1. Please don’t operate the visible spectrophotometer casually when you don’t know its performance deeply, operations shall be carried out under the guidance of operators skilled in the visible spectrophotometer.

2. Pay attention to sunscreen, anti drenching, damp proof and anti vibration. In case the visible spectrophotometer is dampened, put it in a cool and ventilated place, package after drying.

The gas analyzer is a flow analysis instrument for the measured gas composition. In many production processes, especially those with chemical reactions, it is often not enough to automatically control processes according to physical parameters such as temperature, pressure and flow. There are many kinds of gas analyzers due to the diversity of the gas types being analyzed and the analytical principles. The commonly used gas analyzers include infrared gas analyzers, laser gas analyzers, ultraviolet gas analyzers, thermal conductivity gas analyzers, electrochemical gas analyzers, etc. The gas detector is a kind of gas leak concentration detection instrument, including portable gas detector, handheld gas detector, fixed gas detector, online gas detector. The following is an introduction to the difference between a gas analyzer and a gas detector

Connector is also called as plug socket, it's widely used in all kinds of electrical circuits to connect or disconnect the circuit. The electrical connector has many types and wide applications, proper selection of circular connector is also an important way to improve the connector reliability.

Electrical parameter requirements

1. Rated voltage
   Rated voltage is also known as working voltage, it's mainly determined by the insulation materials used by circular connector and the distance between the contact pairs. Some component devices may not be able to perform their functions when using below the rated voltage.
2. Rated current
   Just the same as the rated voltage, the circular connector may not work normally in the current below the rated current. In the design of circular connectors requirements for rated current are met through the thermal design of the circular connector, because the contact pairs will be heated when current passed due to the existence of conductor resistance and contact resistance.

The detection modes of photoelectric sensor are divided into the following categories: opposite type, reflective plate type, polarizing reflective plate type, direct opposite type, wide beam type, focused mode, fixed-field type and adjustable-field type. Ultrasonic sensor includes two detection mode of opposite type and proximity.

Opposite type
Transmitter and receiver of the opposite detection mode are installed in an opposite mode, the light from the transmitter aims at the receiver directly. When the object blocks the beam, output of the sensor changes to indicate that the detected object is detected.
Reflective plate type
In the reflective plate detection mode, a sensor has both transmitter and receiver. The light emitted from the transmitter shines upon the reflective plate, the reflected light returns to the receiver. When the object blocks the beam, the detected object is detected.

What are the general debugging steps of the automatic transfer switch?

1. Put the double power on the adjustment table and connect the phase line and neutral line ( zero line).
2. For three-pole switch connection, the common and spare zero line need to be connected to zero line terminal (NN and RN).
3. After connecting lines, recheck the lines and then turn on the master switch of the commissioning table, turn on the common and standby power supply. 

In addition to comprehensive parameter testing and effective screening of relays, proper use of relays is also an effective way to improve the reliability of relays. Conversely, improper use will shorten the life of the relay. How to improve the reliability of the relay? Here are some suggestions for your reference.

• Reasonable selection of the working voltage of the relay
  The pull-in voltage of the relay is generally only one-half to two-thirds of its rated working voltage. However, when using the relay, it must work at its rated working voltage, but not the pull-in voltage as the working voltage. This is because, under the condition of the pull-in voltage, although the relay has been operated, the pressure between the moving contacts has not reached the specified value, which will cause the contact resistance between the contacts to be too large, if the contact at high current conditions, when working, it will increase the contact power, which will easily lead to contact ablation and shorten the working life.

Angle of measurement

In order to ensure accurate measurement, keep the infrared thermometer following the surface normal direction of the measured object as possible in measurement (perpendicular to the target surface). If you fail to guarantee the instrument in the normal direction, it is supposed to measure in 45 degree angles with the normal direction, otherwise the displayed value of the infrared thermometer will be low.

Industrial Personal Computer is called industrial PC for short, it's mainly used in the industrial production; Normal computer is called PC for short and is mainly used in personnel or business. Because of the different applications, the technical requirements are different. Ordinary household or office computer is a civil class, while the industrial PC is a industrial level, which has special requirements in structure and other aspects.
On the appearance, the normal computers are open with many heat dissipation holes on the appearance, only a power fan is used to blow outwards to dissipate heat. However, the industrial PC case is completely closed and it's much heavier than the normal computer, meaning that its material is thicker and stronger. It not only has a fan inside, but also another fan to ensure the positive pressure in the case.

Industrial PC is called industrial control computer for full, it is a computer specially designed for industrial control, and is used to monitor and control the machine equipment, production process and data parameters in the production of industrial control computers.
Industrial PC often runs in a bad environment and has higher requirements on the data security, so industrial PC usually has special design, such as reinforcement, dustproof, moisture-proof, anti-corrosion and radiation protection.
Industrial PC also has higher demand for expansibility, the interface design needs to meet specific external devices, so the industrial PC needs to be customized to meet the demand in most cases.
We should know the following clearly on how to choose an industrial PC: which equipment is the industrial PC used; if the communication interface of the industrial PC is sufficient; whether the product quality is up to the standard.

What is the fiber optic sensor

Fiber optic sensor is a medium that transmits light waves by the principle of complete internal reflection of light, it consists of a core and cladding with a high refractive index. The refractive index of the cladding is smaller than that of the core, and its diameter is about 0.1mm～0.2mm. When the light penetrates into the fiber core through the end face and reaching the interface with the cladding, the light is reflected back to the fiber core due to the complete internal reflection of the light. After constant reflection, the light propagates along the fiber core and has only a slight attenuation. In actual detection process, the fiber optic sensor guides the light emitted by the transmitter to the detection point through light-guide fiber, and then guides the detected optical signal to the receiver through light-guide fiber, the detection is thereof realized. According to the different manner of execution, the fiber optic sensor can also be divided into various types, such as opposite type, diffuse reflectance type. Fiber optic sensor can detect objects in the far area. Due to the fiber loss and fiber dispersion, the intermediate amplifier shall be set at a proper position for long-distance fiber transmission system, so as to process and amplify the attenuated and distorted light pulse signals.

Whether low-voltage circuit breakers are installed properly, which will directly affect its performance and safety. Generally pay attention as follows:

1. Before installation, the technical parameters listed on the nameplate of the low-voltage circuit breaker should be checked for compliance with the requirements.
2. Low voltage circuit breakers should be installed vertically, and the wired in front of the board are allowed to be mounted on metal brackets or metal backplanes, but the low-voltage circuit breakers that are wired behind the board must be mounted on the insulating base plate. The bracket or bottom plate of the fixed low-voltage circuit breaker must be flat to prevent damage to the insulating base when the screws are tightened. In order to prevent accidents caused by arcing, the copper busbar of the low-voltage circuit breaker should be packed with 200mm insulation or phase-interval arc plate from the insulation base.

How does a transformer work? Transformers mainly applies electromagnetic induction principle to work, the working principle details are as follows: When the primary side of the transformer is applied with the alternating voltage U1 and the current flowing through the primary winding is I1, then the current will generate alternating magnetic flux in the iron core to generate electromagnetic connections between the primary winding and the secondary windings.

Variable Frequency Drive (VFD), aka variable speed drive (VSD), generally it's using for controlling 3-phase AC motor in variable speeds. It's important to know, control 1-phase motor speed by a VFD may cause overheat of the motor, as well as the service life. It's recommended to upgrade the motor to three phase AC motor, which you can also connect the 3-phase motor to single phase power supply by using a single phase to three phase VFD, then control the speeds. Anyway, in technical it's possible to use a VFD for single phase motor speed controls, here ATO will show you details about running a single phase motor on a VFD.

Brushless DC motor consists of the motor and drive, is a typical mechatronic product. The stator windings of the motor are mostly made using three-phase symmetrical star connection, which is very similar to the three-phase asynchronous motor. Magnetically charged permanent magnets are attached to the rotor of the motor. In order to detect the polarity of the motor rotor, a position sensor is provided in the motor.

Power supply is an important part of the circuit design, and the stability of the power supply determines the stability of the circuit to a large extent. Linear power supply and switching power supply are two common power supplies, and they have a great difference in the principles which determine the difference between the two applications.

For wirings of three phase shunt capacitors or three phase capacitor banks composed of three single phase shunt capacitors, the most commonly used are star and triangle wirings. Star wiring includes single star wiring and double star wiring while triangle wiring includes single triangle wiring and double triangle wiring. The double triangle wiring is gradually eliminated due to complicated wiring and high cost. Low voltage shunt capacitors mostly use triangular wiring and high voltage shunt capacitors, especially for high voltage shunt capacitors with large capacity, mostly use star wiring.

Self-healing type low voltage shunt capacitor is suitable for the AC power system with working frequency 50Hz or 60Hz, rated voltage 1000V and below and is connected in parallel with load, in order to improve the power factor of system and reduce line loss, improving the voltage quality. It is widely used to improve the efficiency of power supply equipment, local compensation of the inductive equipment such as motor and transformer and electric furnace, electric traction engine, UPS systems and power system harmonic filtration and other aspects.