Power quality (Power Quality), in a general sense, refers to high-quality power supply, including voltage quality, current quality, power supply quality and electricity quality. For portable power quality analysis, the analyzer uses a management backend (a widely popular portable tablet or laptop computer) + acquisition front-end mode (similar to the Fluke 1760 mode). The collection front-end adopts the black box design of high-speed DSP digital processor, without excessive operation and complex display, so the calculation speed is fast, the reliability is good, the anti-interference is strong, the wiring does not need to be disassembled, and the operation is convenient and fast. The management background can use the tablet computer of the open source Android operating system for measurement and data management, and the operation is more convenient; or configure a laptop computer with a wifi module
Most of the voltage sags affecting factories are caused by grid faults and transmitted to factories.
1). Possible external causes
Lightning strikes cause short-to-ground faults and cause large currents in the distribution lines, resulting in a sudden drop in power supply voltage. This voltage sag affects a large area, and the duration generally exceeds 100ms;
Power supply equipment failure;
Ground Fault;
In a traffic accident, the vehicle hit a telephone pole;
Line failure, caused by animals, heavy snow, strong winds and excavation, etc. caused pressure drop;
Reclosure, large current caused by sudden load causes a voltage drop;
2). The internal main reason that may occur: the start of the large motor load;
The factory cannot be warned of voltage dips in advance.
Voltage dip waveform
Effects of voltage dips
The damage degree of voltage sag is closely related to the sensitivity of equipment. Different equipments have different sensitivity to the same voltage sag. Therefore, different equipment manufacturers alliances in the world have developed a variety of different sensitivity curves, such as SEMI F47 , ITI (CBEMA), FIPS, etc. For example: refrigeration electronic controller, when the voltage is lower than about 80%, the controller action will cut off the refrigeration motor, resulting in huge economic losses; a high-end tester, when the voltage is lower than about 85%, the chip burns, the tester Stop working, the internal electronic circuit board is faulty; programmable controller (PLC), when the voltage is lower than about 81%, the PLC stops working; some I / O devices, when the voltage is lower than about 90%, the duration is only a few The cycle will be cut off; precision mechanical tools, controlled by robots to perform precision machining such as drilling and cutting of metal parts. To ensure product quality and safety, the working voltage is generally set to 90%. When the voltage is lower than this value and the duration exceeds 2 to 3 cycles, it will be tripped; DC motor, when the voltage is less than about 80%, the DC motor is tripped; speed-controlled motor (VSD), when the voltage is less than about 70%, the duration exceeds 6 cycles At that time, the VSD was cut off. For some motors in the fine processing industry, when the voltage is less than about 90% and the duration exceeds 3 cycles, the motor will be tripped and exit the operation; AC contactors, some studies have shown that when the voltage is less than about 80% , Or even higher, the contactor will trip; the above results in online material scrapping, reduced output, prolonged equipment restart, and possible equipment damage and corresponding increase in labor costs
Precautions
Before measuring resistance, the circuit to be tested must be fully discharged and completely isolated from the power circuit.
If the test pen or power adapter is damaged and you need to replace the power, you must replace the test pen and power adapter with the same model and the same electrical specifications.
Do not use the instrument when the battery indicator indicates that the power is exhausted. If the instrument will not be used for a long time, please remove the battery and store it.
Do not store or use this instrument in high temperature, high humidity, flammable, explosive and strong electromagnetic fields.
Please use a damp cloth or detergent to clean the shell of the instrument. Do not use abrasives or solvents.
When the instrument is wet, please dry it before storing
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