Tag: difference between

As the common part of the electrical device, both the surge protection device and lightning arrester have the function of preventing from over-voltage, especially preventing from the lightning over-voltage. However, the two have great differences.

• Different voltage level from the perspective of application field
• Different protecting objects
• Different insulation level or withstand voltage level
• Different installation position

Current transformer is mainly used to measure the current of busbar and primary side with iron core coils in AC occasion. It can detect the DC current, can be single core or dual cores, generally, it's equipped with auxiliary DC winding. Such a structure is simple, reliable and slow. Technology and design of the current transformer are complex, its common precision is 5%, it's difficult to reach 0.5% because phase position and compensation are difficult. A current transformer is an electrical component that turns large current into small current, it doesn't change the current frequency but only the size. Its secondary side current is 5A, that means the output rated current is 5A. It's mainly used for electrical control, measurement, protection and signal.

The gas solenoid valve is used for various ambient temperature, high temperature, negative pressure, low pressure and high pressure applications. The applicable fluid is air, nitrogen, oxygen, hydrogen, helium, carbon dioxide gas, argon gas, methane and other gas pipelines. Generally, solenoid valve for gas is mainly used in wide applications such as medical apparatus and instruments, rubber plastic machinery, clothing equipment, drying equipment and pharmacy industry, cooling industry, HVAC industry, electroplating coating industry, food and beverage industry and vacuum equipment industry.

As everyone knows, direct starting of water pump would cause the water hammer effect. Namely when the water pump starts and stops, water impacts the pipe and cause a serious water hammer. When the power is off suddenly or the valve turns off quickly, a water impact wave generates due to inertia of pressure flow, which is like the knock of a hammer, so it’s called water hammer. Sometimes the force generated from water impact wave may be great and damage valve or pump, therefore, to avoid the negative effect of water hammer effect, the pump’s rotation speed should increase to the rated speed slowly when it’s started. Two methods are applicable, one is the variable frequency starting, another is the soft starting.

Safety relay has special color, generally yellow. Current safety relay acts reliably and flexibly, it's mainly used to control the power supply circuit. When an emergency occurs, the circuit controlled by the safety relay is disconnected by pressing the emergency stop switch, thus ensuring safety.

Infrared temperature measurement technology plays an important role in production, product quality control and monitoring, on-line fault diagnosis and safety protection, as well as energy saving. Compared with the contact-type temperature measurement method, infrared temperature measurement has the advantages of fast response time, non-contact, safe use and long service life. Non-contact infrared thermometer involves three major series of portable, on-line and scanning thermometer, with various accessories and computer software. Moreover, each series has different types and specifications. Among these thermometers with various specifications, it is very important for users to choose a correct type of infrared thermometer.

Iron core of the AC contactor is usually laminated by silicon steel sheet, so as to reduce the eddy current and hysteresis loss generated by alternating magnetic field in iron core, avoid the iron core overheating. However, iron core in the DC contactor's coil would not generate eddy current and there is no heating problem in DC core, so the iron core can be made of a complete cast steel or cast iron. Coil of DC circuit has no inductance, so the coil has more turns, thus leading to large resistance and copper loss. In order to keep a good heat dissipation for the coil, the coil is generally made into a thin and cylindrical shape. Coil of AC contactor has less turns and small resistance, but the coil also gives heat, so the coil is generally made into a fat and short cylindrical shape. Meanwhile, a clearance is left to facilitate heat dissipation while avoiding the coils from being burned out. In order to eliminate vibration and noise generated by electromagnet, a short circuit ring is embedded on the surface of static iron core of the AC contactor, while the DC contactor doesn't need a short circuit ring.

Industrial thermocouple and RTD protective casing are almost the same. Some temperature measuring elements are small in size, such as the armored type, and they also have similar shape. So, how to identify whether it is RTD or thermocouple without nameplate or unknowing the type? The following methods are listed to figure out the RTD and thermocouple for your reference.

The common line reactors in electrical power system include series reactors and paralleling reactors. Series reactors are mainly used to limit short-circuit current or ultraharmonics in filter by connecting with capacitor in series or in parallel. The line reactors in power grid of 220kV, 110kV, 35kV and 10kV are used to absorb the idle work of charging capacity of cable line. Operating voltage can be adjusted by adjusting the number of line reactors in parallel. Ultra-high voltage paralleling reactor can improve the operation conditions relating to reactive power of electrical power system including:

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

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.

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.

In the actual use of some low pressure and medium pressure piston type portable air compressor, the two stage compression is often used. The intermediate cooler is set. After the cooling of high temperature air discharged from single stage compression, it is then inhaled into two stage cylinder for two stage compression so as to reach the required pressure. Adopt two stage compression, because if use single stage compression to obtain higher air pressure, the pressure ratio (the ratio of the exhaust pressure and suction pressure) is too large, so that the compression process.

The solenoid valve is one of the products for fluid control automation. According to the start-up working model of the solenoid valve, it can be divided into the most frequently-used two categories: pilot-operated solenoid valve and direct acting solenoid valve. However, if not choose the right one, it easily causes the solenoid valve does not work. Meanwhile, it will somewhat affect the safety of the application. Then, how to distinguish the difference between pilot-operated and direct acting solenoid valve? How to choose the right one for the better application? The following will give you some enlightenment.

Circuit breakers and fuses can protect the electric equipment and lines from short circuit. Actually, both have their own characteristics. Circuit breakers are used to switch on and off the load circuit as well as cut off the fault circuit, so as to ensure the safety. The fuse is used as a protector by melting itself when the current is too high or exceeds the load current. It is completely different from the circuit breaker on the breaking current. Its function can be easily understood by the commonly used fuse in our home.

AC motors are divided into two types, synchronous motors and asynchronous motors which are also called induction motors. The biggest difference between synchronous motors and asynchronous motors (induction motors) is whether the speed of rotor is consistent with the speed of the rotating magnetic field in the stator. If the rotor’s rotation speed and the stator’s field speed are the same, it is called synchronous motor; if not, it is asynchronous motor. Furthermore, there are big differences specific to the performance parameters and applications between the two.

DC motors are mainly divided into brushless DC motors and brushed DC motors.
Brushed DC motor
DC motor is famous for its good start-up performance and speed performance, in which brushed DC motors use mechanical commutator to make driving simple, see the model diagram shown in Figure 1.
The motor is mainly composed of a stator made of permanent magnetic material, a rotor (armature) wound with a coil winding, a commutator and a brush. As long as the brush A and B at both ends of a certain direct current, the motor commutator will automatically change the direction of the motor rotor magnetic field, so that DC motor rotor will continue to run.

A contactor is mainly used in a primary loop, which can go through a large current (several hundred to about one thousand Amps). While a relay is used in a secondary circuit to achieve various control functions, which can only go through a small current (several to decades Amps). Functions, contacts opening and closing situation of the two subject are different.

Solid state relay (SSR) is a non-contact switch composed of solid-state electronic components with high reliability, non-contact, no spark, long life, no noise, no electromagnetic interference, high switching speed. Electromechanical relays (EMR) is a kind of magnetic switch made up of multi-coils, movable elements, contact system etc. and it is easy to drive and widely used in all the areas. Then what are they differences? Which one is better?

Stepper motors is used in open-loop control, thus it is simple, low cost and can be widely used. However, the open-loop control of the stepper motor cannot avoid the inherent disadvantages of the stepper motor itself, that is, resonance, oscillation, step loss and difficult to achieve high speed. Correspondingly, the closed-loop control of stepper motor can make up these shortcomings, and have the advantages of open-loop drive and brushless DC servo motor.