How to choose a smart meter

1, the instrument size. That is the size of the instrument, this is a very basic problem. The digital display should be installed on the cabinet, so consider the overall coordination. If it is too large, it may not fit. If it is too small, the display number is not clear. In addition, the large-sized instrument has a stronger function expansion and the same function price. It may be expensive. Smaller instruments may have poorer function expansion. 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, shows the number of digits. This is directly related to the measurement accuracy of the digital display. In general, the higher the number of display digits, the more accurate the measurement, and the more expensive the price, mainly in the following categories: two (99, special); three (999, (fewer); three and a half (1999, ordinary digital meters dominate the mainstream); four digits (9999, smart digital displays dominate); four and a half (19999); four and three quarters (3999); five and More than five digits (common in counters, cumulative meters, and high-end meters), the user can select several digits of the digital display based on the measurement accuracy requirements.

3, input signal. Refers directly to the meter's measurement signal. Some industrial signals are directly connected to the meter. Some signals are converted to the meter. The nature of the measurement signal must be clarified. Otherwise, the purchased meter cannot be used or even damage the meter. Original equipment. To find out the type of signal: current or voltage, AC or DC, whether it is a pulse signal or a linear signal, etc., and also the size of the signal. The name of the instrument is not the same as the input signal. For example, the input signal is a 0-75mVdc current meter (name is ammeter, the input signal is a voltage signal, because the current through the shunt to obtain the voltage signal); the input signal is 0- 10Vdc tachometer (named tachometer, the input signal is a voltmeter, because the frequency converter converts the speed signal into a voltage signal).

4, working power. All digital displays require a working power supply. The power supplies for the digital display are: 220Vac; 110/220Vac; 85-265VAC/DC switching power supply, 24Vdc (usually ordered), and 5Vdc (small panel meter).

5, meter function. Instrument function is generally modular, optional, the instrument price will vary with the function is different, the digital display mainly has the following optional features: alarm function and the number of alarm output group (that relay output) , Feed power output and output voltage size and power, transmission output and transmission output type (4-20mA or 0-10V, etc.), communication output and communication methods and protocols (RS485 or RS232, is Modbus or other protocol ) For the regulation and control instruments, there are more optional functions. Specifically, a standardized model should be selected by referring to the manufacturer's selection spectrum. After communicating with the manufacturer and confirming that it is correct, it can be ordered.

6, several more important parameters to look at: measurement accuracy (the smaller the value more accurate), the response speed (the smaller the value of the faster response), the working environment, the temperature coefficient (the smaller the value is affected by the temperature, the smaller), overload Ability 7, special requirements. If the user has special requirements, he or she should raise it and let the manufacturer confirm whether it can meet the requirements. Do not take it 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 digital display is not complicated. For a simple digital display, it can be used normally. For those who use it for the first time or select a complicated digital display, they can grasp the above points. Buy the right product.