1, the accuracy of the meter
China's electrical instrumentation is divided into seven levels of 0.1, 0.2, 0.5, 1.0, 1.5, 2.5, 5.0. The meaning of this level refers to the error percentage of the full scale of the meter. For example, the level is 0.5, the input current is 5A, and the meaning of level 0.5 here means that when the ammeter is input 5A, its maximum error will not exceed 0.5%.
There is also a description of the error called uncertainty. China has not yet fully adopted the instrument industry, so it will not be described.
2, digital display and analog table
Advantages of the digital meter: accurate reading and high precision
The strength of the analog table: According to the swing of the pointer, the trend and range of the measured are all seen. Therefore, there is also a digital display with a light column. In order to realize this function of the analog meter, it is generally used to measure the liquid level. It looks more intuitive.
3, the instrument's power supply
Generally divided into transformer power supply, switching power supply, battery power supply.
Switching power supply: The advantage is that the input voltage range is 70-250V wide. The disadvantage is that the anti-interference ability is poor, especially in places with large harmonics, such as steel mills, the instrument power supply part is easily damaged.
Advantages of transformer: anti-harmonic anti-interference, disadvantages: single input voltage level, voltage level is required when ordering, DC power supply is not available.
4, input measurement signal
The input measurement signal is divided into half, AC signal and DC signal. The accuracy of the DC signal is generally much higher than the AC signal.
5, true RMS and average
The multimeter shows the average.
The value displayed on the installed instrument is generally true RMS, with strong anti-interference ability, anti-harmonic and frequency variation.
6, the size of the exterior
Generally there are 120 96 80 squares
7, additional features
In addition to the usual measurement functions, the instrument has additional modules.
1. Communication module supports RS-485 modubus RTU protocol
2. Transmitter module 4-20mA transmission measurement signal
3. The control module outputs an over-range alarm for the set voltage and current value through the relay output.
8, ratio setting
The full scale of the current, according to the transformer ratio during the actual installation
It can be arbitrarily set by the user from the 5A-8000A according to the national standard series values.
9, response speed
Ordinary digital display meters generally use a dedicated chip. Because the dedicated chip has many functions, the response time is relatively slow. Generally, only 3-5 valid values ​​can be output in one second.
In some special occasions, where the customer requests a fast response, the response speed of this parameter will be involved.
10, the above said so many are for the power frequency 50Hz instrument
There are also some special instruments on the market, such as the IF 400Hz watch, mainly for aviation; there are also high frequency meters, such as 20kHz, which are mainly used in some medium and high frequency equipment, such as super audio power supply, inverter output current.
11, data acquisition software
On the instrument with 485 interface, many users usually need to write the acquisition software to the electronic professional production digital display controller, so that the customer's production efficiency can be maximized, and serve the customer as much as possible.
Faced with the numerous digital electrical instruments on the market, the model is complicated. When ordering, it is not the mistake, that is, it is not what you want.
Today, I just took this opportunity to discuss with you how to buy a digital electrician. I hope to help everyone. The electrician instrument is a general term, and the multimeter and the mounted instrument are all electrical instruments. The main thing we talk about here is the purchase of the mounted digital display.
Wall switch and socket, push switch and socket, Home switch socket
Guangdong Shunde Langzhi Trading CO., Ltd , https://www.langzhielectrical.com