Digital display meter, the abbreviation of digital panel meter (DIGITAL PANEL METER), generally uses LED digital tube display, and LCD liquid crystal display, used for industrial signal measurement, monitoring, control, regulation, transmission, remote communication. Pay attention to the following issues when selecting a model:
1. Instrument size. That is the size of the instrument, this is a very basic problem. The digital display meter should be installed on the cabinet, so it is necessary to consider the overall coordination. If it is too large, it may not be installed. If it is too small, the display digits cannot be clearly seen. It may be expensive, and the small size of the instrument may be less functionally expandable. At present, the international standard sizes of digital display surface boards are mainly the following: 48 * 24mm; 48 * 48mm; 48 * 96mm; 72 * 72mm; 96 * 96mm; 96 * 48mm; 160 * 80mm.
2. Display digits. This is directly related to the measurement accuracy of the digital display. Generally speaking, the higher the number of display digits, the more accurate the measurement and the more expensive the price. There are mainly the following types: two digits (99, special); three digits (999, polar (Less); three and a half (1999, the common digital display is the mainstream); four (9999, the smart digital display is the mainstream); four and a half (19999); four and three quarters (3999); five and More than five digits (common in counters, accumulation meters and high-end meters), users can choose a few digits according to the measurement accuracy requirements.
3. Input signal. Refers to the measurement signal directly input to the instrument. Some industrial signals are directly measured by the instrument, and some signals are converted to the instrument after conversion. The nature of the measurement signal must be clarified, otherwise the instrument purchased cannot be used, or even damage the instrument and Original equipment. To understand the signal type: current or voltage, AC or DC, pulse signal or linear signal, etc., also need to understand the size of the signal. The name of the instrument is not the same concept as the input signal. Here are a few examples: the input signal is an ammeter of 0-75mVdc (the name is an ammeter, but the input signal is a voltage signal, because the current passes through the shunt to obtain the voltage signal); the input signal is 0- 10Vdc tachometer (the name is tachometer, but the input signal is a voltmeter, because the inverter converts the speed signal into a voltage signal).
4. Working power supply. All digital display meters need working power. The main working power of digital display meters are: 220Vac; 110 / 220Vac; 85-265VAC / CD switching power supply, 24Vdc (generally customized), 5Vdc (small panel meter).
5. Instrument function. The functions of the instrument are generally modular and optional. The price of the instrument will also vary with different functions. The digital display mainly has the following optional functions: alarm function and number of groups of alarm output (ie relay action output) , The size and power of the power supply output and output voltage, the type of transmission output and transmission output (4-20mA or 0-10V, etc.), communication output and communication methods and protocols (RS485 or RS232, Modbus or other protocols ), For regulating and controlling instruments, there are more optional functions, specifically refer to the manufacturer's selection spectrum to select a standardized model, and communicate with the manufacturer and confirm that the order is correct.
6. A few more important parameters should be paid attention to: measurement accuracy (the smaller the value, the more accurate), the response speed (the smaller the value, the faster the response), the working environment, the temperature coefficient (the smaller the value, the less affected by temperature), and overload ability
7. Special requirements. If the user has special requirements, it should be put forward to let the manufacturer confirm whether they can meet the requirements, not to be taken for granted, such as: IP protection level, high-temperature working occasions, strong interference occasions, special signal occasions, special working methods, etc.
In fact, the selection of the digital display table is not complicated. For simple digital display tables, you can generally buy it. For users who use the digital display table for the first time or choose a complex function, as long as you grasp the above points, you can also choose it. Buy to buy
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