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Why We Use VFD - Efficiency and Performance

Figure 1: Someone is using the VFD.

The Variable Frequency Drive (VFD) is a device widely used to convert the constant voltage of an autonomous AC power source into a variable voltage for controlling the torque and speed of the motor. They are ideal for motors that drive loads on mechanical equipment. A VFD offers higher efficiency than simple inline motors, as well as a degree of control not available with simple drive motors. These factors can save energy costs, improve production performance and extend motor life.

Challenges of VFD

The VFD is also known as VSD and ASD. Troubleshooting and testing are usually performed by experts using a variety of test instruments, including oscilloscopes, multimeters, or other tools. These tests may involve some degree of trial and error using the ancient method of elimination. Because of the complexity of the motor system, testing is usually done once a year unless the system starts to fail. Given that equipment often lacks or has an incomplete record, it’s difficult to determine where to start testing. This includes recording specific tests and measurements performed previously, the completed work, or the individual components after adjustments. Advances in testing technology have solved some of the challenges. New instruments such as the Fluke Motor Drive Analyzer (MDA-510 and MDA-550) are designed to make VFDs more efficient, and to document the process step by step. These reports can be saved and compared with subsequent test results for a more complete understanding of the motor driver's maintenance history.

Figure 2: The Fluke Motor Drive Analyzer.

More artical information please visit https://okmarts.com/news/why-we-use-vfd-efficiency-and-performance.html

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What does the Tire Pressure Sensor Fault Mean?

Figure 1: The tire pressure monitoring system.

Automotive sensors are the fastest growing and most used type in recent years. The development of the automotive industry stimulates the improvement of automotive pressure sensors. Advanced manufacturing and process technology strengthen the performance of sensors, and tire pressure monitoring is increasingly accurate. At present, in order to ensure the safety of driving, most car tires are equipped with pressure sensors to detect pressure change. When the tire pressure reached a reasonable value, it can improve safety, but also can save fuel consumption, according to the relevant data statistics.

Tire Pressure Sensor Working Principle

Tire pressure monitoring system (TPMS) mainly has two kinds of solutions, direct system and indirect system. A direct tire pressure monitoring system is the use of pressure sensors installed in each tire to directly measure the tire pressure, and display and monitor it. When the pressure is too low, the system will automatically alarm.

Indirect TPMS

As for the indirect tire pressure monitoring system, the wheel speed sensor of the automobile ABS system compares the speed difference between tires, so as to achieve the purpose of monitoring tire pressure. And the main disadvantages lie in the following three aspects. The exact instantaneous pressure of each tire cannot be displayed. It can not alarm when the pressure of the same axle or wheel on the same side or all tires drop at the same time. The factors such as speed and detection accuracy cannot be taken into account simultaneously.

Direct TPMS

The direct tire pressure monitoring system is divided into two types that are active and passive. * Active System The active system is achieved by using mems technology on silicon capacitive or piezoresistive pressure sensors. The pressure sensor is installed on each wheel rim, transmitting a radio frequency signal. Then the wireless receiver installed in the cab receives the pressure sensor signals, after a certain signal processing, and shows the tire pressure. The active system is a relatively mature technology, and the developed module can be applied to the tires of various brands. But its disadvantage is also prominent, whose induction module needs battery power, so there is a problem of service life.

Figure 2: Some tire pressure sensors.

* Passive System The sensor of the passive tire pressure monitoring system is designed by a surface acoustic wave, and it produces a surface acoustic wave through a radio frequency electric field. When the surface acoustic wave reaches the surface of the piezoelectric substrate materials, there will be changes. By detecting the change, the tire pressure is known. Although this type of technology does not need battery power, it requires transponders to be integrated into tires, requiring common standards from tire manufacturers. The monitoring system can detect the abnormal condition of tire pressure only with high resolution. Battery life is limited, and capacity is also affected by temperature. In order to improve the reliability of the monitoring system, it is better for the sensor to carry out passive detection. The research shows that the information collected by a tire pressure sensor can be used to monitor the fault of the vehicle suspension system and correct the navigation system.

More artical information please visit https://okmarts.com/news/what-does-the-tire-pressure-sensor-fault-mean.html

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Car AC Compressor Troubleshooting-- Best Suggestions

Figure 1: Cutaway 3D model of a car AC compressor.

Cylinder Block and Cylinder Head Repair

Using a straight edge and a feeler gauge to examine the flatness error between cylinder head, cylinder block, crankcase and bottom cover, which should not be more than 0.05mm, otherwise, you should grind it. If there are cracks in the cylinder block and cylinder head through observing or knocking, replace them with new ones.

Cylinder Wear Repair

Use the cylinder gauge to check the wear condition of the cylinder. If the cylindricity error is more than 0.25mm and the roundness error is more than 0.08mm, you should bore and grind the cylinder. The boring and grinding operation shall be carried out according to the repair dimension, generally divided into five grades and each step shall be increased by 0.25mm. When the cylinder is bored to the last-level repair dimension, you can repair it by reinserting the sleeve. When you insert the case, the interference of the matching shall be 0.05mm ~ 0.12mm.

Crankshaft Repair

Through visual inspection, if you find cracks on the crankshaft, replace it with a new one. If the clearance between crankshaft journal and ball bearing is more than 0.02mm, you could repair the journal by chromium plating or surfacing welding, or replace it with new parts. If the roundness error of the connecting rod journal exceeds 0.10 mm, you should ground the connecting rod journal or replace it. If the limit wear is exceeded, you must replace the connecting rod journal.

Repair of Connecting Rod Group of the Piston

The piston connecting rod group includes a piston, a piston ring, a piston pin, and a connecting rod. If the connecting rod is bent, you should correct it. If there are cracks, replace the connecting rod with a new one. The new piston shall meet all technical standards. The matching clearance between the new piston and the cylinder is 0.03mm-0.09mm. When the fit clearance between connecting rod bearing and journal exceeds 0.12mm, use a new bearing instead.

Figure 2: Connecting rod group of a piston compressor manufactured by Kawasaki, including connecting rod, piston, piston pin, etc.

More artical information please visit https://okmarts.com/news/car-ac-compressor-troubleshooting-best-suggestions.html

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If a prosperous year doesn't come again, it's difficult to morning again in a day. Encourage yourself in time, and years don't wait for others

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Car AC Compressor Troubleshooting-- Best Suggestions

Figure 1: Cutaway 3D model of a car AC compressor.

Cylinder Block and Cylinder Head Repair

Using a straight edge and a feeler gauge to examine the flatness error between cylinder head, cylinder block, crankcase and bottom cover, which should not be more than 0.05mm, otherwise, you should grind it. If there are cracks in the cylinder block and cylinder head through observing or knocking, replace them with new ones.

Cylinder Wear Repair

Use the cylinder gauge to check the wear condition of the cylinder. If the cylindricity error is more than 0.25mm and the roundness error is more than 0.08mm, you should bore and grind the cylinder. The boring and grinding operation shall be carried out according to the repair dimension, generally divided into five grades and each step shall be increased by 0.25mm. When the cylinder is bored to the last-level repair dimension, you can repair it by reinserting the sleeve. When you insert the case, the interference of the matching shall be 0.05mm ~ 0.12mm.

Crankshaft Repair

Through visual inspection, if you find cracks on the crankshaft, replace it with a new one. If the clearance between crankshaft journal and ball bearing is more than 0.02mm, you could repair the journal by chromium plating or surfacing welding, or replace it with new parts. If the roundness error of the connecting rod journal exceeds 0.10 mm, you should ground the connecting rod journal or replace it. If the limit wear is exceeded, you must replace the connecting rod journal.

Repair of Connecting Rod Group of the Piston

The piston connecting rod group includes a piston, a piston ring, a piston pin, and a connecting rod. If the connecting rod is bent, you should correct it. If there are cracks, replace the connecting rod with a new one. The new piston shall meet all technical standards. The matching clearance between the new piston and the cylinder is 0.03mm-0.09mm. When the fit clearance between connecting rod bearing and journal exceeds 0.12mm, use a new bearing instead.

Figure 2: Connecting rod group of a piston compressor manufactured by Kawasaki, including connecting rod, piston, piston pin, etc.

More artical information please visit https://okmarts.com/news/car-ac-compressor-troubleshooting-best-suggestions.html

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Where is Servo Motor and Servo Drive Used?

Figure 1: Servo motor is a core part of servo system.

With the development of information, communication and automation technology, a wide variety of automatic control devices have been used in industry production and daily life of modern world. As one of the most common devices for automatic control, servo system, constituted by servo motor and servo drive has been widely used in our daily life. With our article here, you can get a deeper understanding where exactly can servo motor and servo drive can be used.

1. What is Servo System?

Servo system, is a feedback control system used to accurately follow or reproduce a process. As one of the key components of a servo system and the execution part of it, servo motor changes the object's position, orientation, state and other output controlled quantity following the input (or a given value). Its task is to amplify, transform and regulate the power according to the requirements of the control command, so that the output torque, speed and position control of the driving device is very flexible and convenient.

2. Components of Servo System

The system is mainly composed of HMI touch screen, PLC, servo drive, permanent magnet synchronous servo motor. The servo motor is the executive mechanism of the movement. It does position, speed and current control, so as to meet the user's functional requirements.

Figure 2: Servo system is composed of PLC, drive, motor, reducer and interface.

3. Features, Uses and Types of Servo System

3.1 Features of Servo System

It needs accurate detection device to compose closed speed and position loop.

Various Feedback and Comparison Principles

There are a variety of feedback comparison principles and methods. According to the different principles of detection device to achieve information feedback and different methods of feedback comparison, there are pulse comparison, phase comparison and amplitude comparison in common use.

High Performance Servo Motor

In NC machine tools for efficient and complex surface processing, the servo system will often be in the process of frequent start and brake. So the ratio of the motor's output torque to the moment of inertia is required to be large enough to generate a large acceleration or braking torque. And also the servo motor is required to have large enough output torque at low speed and smooth operation, so as to minimize the intermediate link in the connection with the mechanical moving part.

More information please visit https://okmarts.com/news/where-is-servo-motor-and-servo-drive-used.html

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Basics of Servo Motor You Should Know

Servo control refers to the effective control of the position, speed and acceleration of certain object to meet a certain purpose. It is one of the most important control methods in modern industry. Servo control system has been so widely used in industry, but do you know the basic knowledge about servo control? Check out this article to learn about how servo control system works and setting up tips.

Figure 1: An example diagram of a servo control cabinet in use.

1. Four Control Modes of Servo Motor

1.1 Torque Control Mode

Torque control is to set the external output torque of the motor shaft through the input of external analog quantity or direct address assignment. For example, if 10V corresponds to 5Nm, when the external analog quantity is set to 5V, the output is 2.5nm. If the load of the motor shaft is lower than 2.5nm, the motor is rotating. When the external load is equal to 2.5nm, the motor does not rotate, and when the load over 2.5nm, rotating direction reverses (usually under the condition of gravity load). The torque can be changed by changing the setting of the analog quantity，or address value by means of communication. It is mainly used in winding and unwinding devices that have strict requirements on bearing capacity of material, such as wire spool device or optical fiber pulling equipment. The setting of torque should be changed at any time according to the change of the winding radius to ensure that the force material takes does not change.

1.2 Position Control Mode

In the position control mode, the rotation speed is generally determined by the frequency of the external input pulse, and the rotation Angle is determined by the number of pulses. In addition, some servos can assign the speed and displacement directly through communication. The position mode is commonly applied to positioning devices because it allows for strict control of speed and position.

1.3 Speed Control Mode

The rotation speed can be controlled by the input of analog quantity or the frequency of pulse. The speed mode can also be positioned when there has outer loop PID of the upper control device to control, but the position signal of the motor or the direct load must be fed back to the upper for calculation.

1.4 Full Closed-Loop Control Mode

Full closed-loop control is a term compared with semi-closed loop control. First of all, let's look at the semi-closed loop control. The exponential control system or PLC sends out speed pulse instructions. The servo accepts instructions and then executes them. In the process of execution, the encoder of the servo itself gives the position feedback to the servo, and the servo itself corrects deviation. The deviation of the servo itself can be avoided, but the mechanical error cannot be avoided for the reason that the control system does not know actual position. The full closed-loop refers to that the servo accepts the controllable-speed pulse instruction from the upper controller, and executes it. During the execution, the position-feedback device on the mechanical device directly feeds back to the control system. The control system detects the the actual deviation through comparison, and gives the servo instruction to correct deviation. Control system controls speed of the servo loop through frequency of pulse signal and then controls position of the servo loop through position sensor (grating ruler, encoder) to complete the position loop of the servo control. This formulation of control which combined servo motor, motion controller, and position sensor control called full closed-loop control.

Figure 2: Work principle of full closed-loop control mode.

More artical information please visit https://okmarts.com/news/basics-of-servo-motor-you-should-know.html

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Air Compressor Troubleshooting and Solutions

With the development of motor technology, compressor is considered as "general machinery", especially in coal chemical industry, machinery industry and other industries. For distance measurement applications, both incremental and absolute encoders can be chosen - from a technical point of view. The advantages of absolute encoders are reflected in accuracy and performance, while incremental encoders seem more economical and practical. A correctly working compressor determines the safe operation of the whole air conditioner or refrigerator. For example, during the operation of piston compressor, there would be burnout, oiler failure or low pressure and gas shortage. Once these problems occur, the appliance would not work right. How to quickly and accurately detect and solve these problems in time affects the compressor operating rate and product output. This article will analyze all common faults of AC compressors and provide solutions.

Figure 1: A refrigeration compressor manufactured by Tecumseh.

From the perspective of airflow, a possible fault is that the wind pressure or the temperature of compressed air is too high, which may cause spontaneous combustion of carbon deposits and explosion of the pressure vessel if the protective device fails. Another possible problem is that the air volume is insufficient or the air volume is too low, which will affect production.

Figure 2: Common failures of compressors

From the perspective of the compressor structure, there are four types of problems: problems of lubrication system, cooling water circuit, compressed air circuit and mechanical failure.

More artical information please visit https://okmarts.com/news/air-compressor-troubleshooting-and-solutions.html

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Where is Servo Motor and Servo Drive Used?

Figure 1: Servo motor is a core part of servo system.

With the development of information, communication and automation technology, a wide variety of automatic control devices have been used in industry production and daily life of modern world. As one of the most common devices for automatic control, servo system, constituted by servo motor and servo drive has been widely used in our daily life. With our article here, you can get a deeper understanding where exactly can servo motor and servo drive can be used.

1. What is Servo System?

Servo system, is a feedback control system used to accurately follow or reproduce a process. As one of the key components of a servo system and the execution part of it, servo motor changes the object's position, orientation, state and other output controlled quantity following the input (or a given value). Its task is to amplify, transform and regulate the power according to the requirements of the control command, so that the output torque, speed and position control of the driving device is very flexible and convenient.

2. Components of Servo System

The system is mainly composed of HMI touch screen, PLC, servo drive, permanent magnet synchronous servo motor. The servo motor is the executive mechanism of the movement. It does position, speed and current control, so as to meet the user's functional requirements.

Figure 2: Servo system is composed of PLC, drive, motor, reducer and interface.

More inforamtion please visit https://okmarts.com/news/where-is-servo-motor-and-servo-drive-used.html