Three terminal isolation of the hottest AC current

Three terminal isolation of AC current isolating distributor

brief analysis of isolated safety barrier by 2020

1 Since the three-way isolation mode is adopted, the system grounding line is not required, which brings great convenience to the design and site construction

2. The requirements for instruments in hazardous areas are greatly reduced, and the AC current distributor is isolated at three ends_ For Taihua instruments, there is no need to use isolated instruments on site

3. Because the signal lines do not need to be grounded together, the stability and anti-interference ability of the detection and control loop signals are greatly enhanced, thus improving the reliability of the whole system

4. The isolated safety barrier has stronger input signal processing capability, and the AC current isolation distributor is isolated at three ends_ Taihua instrument can receive and process signals such as thermocouple, thermal resistance and frequency, which is impossible for Zener safety barrier

5. The isolated safety barrier can output two mutually isolated signals to be used by two equipment using the same signal source. The AC current isolation distributor is isolated at three ends_ Taihua instrument, and ensure that the signals of the two equipment do not interfere with each other, while improving the electrical safety insulation performance between the connected equipment

common faults of temperature transmitter

the technology of temperature transmitter has been very mature, which is very common in various factories. The temperature transmitter is often used with some instruments, and there are often some small faults in the process of supporting use. Common faults and solutions are as follows

first, the transmitter output does not change when the temperature of the measured medium increases or decreases. This situation is mostly caused by the sealing of the temperature transmitter. It may be because the temperature transmitter is not well sealed or the sensor is accidentally welded with a small hole during welding. This situation generally needs to be solved by replacing the transmitter shell

second, the output signal is unstable, which is the reason for the temperature source. The temperature source is an unstable temperature. If the instrument display is unstable, it is the reason for the instrument's weak anti-interference ability

third, the transmitter output error is large. There are many reasons for this. It may be that the resistance wire of the selected temperature transmitter is wrong, which leads to the wrong range. It may also be that the transmitter is not calibrated properly when it leaves the factory

the following problems must be paid attention to when using the safety bolt

1. The selected Zener safety barrier shall have the explosion-proof certification of the explosion-proof testing agency and have the explosion-proof certificate

2. select the explosion-proof grade (explosion-proof mark of safety barrier) of safety barrier according to the dangerous area (zone 0, zone 1 and zone 2) of the work site, the gas level and temperature, and the continued weak and stable market group of steel-making pig iron market, so as to make it conform to the above explosion-proof environment. The energy transmitted to the site is limited by the safety barrier to ensure site safety

3. select the polarity of the safety barrier (positive polarity, negative polarity or AC polarity) according to the working voltage of the instrument used on site and its obvious advantages over other packaging materials

4. according to the number of signal transmission lines, select the number of channels of safety barriers (single channel, double channel, three channel), and the transmission lines are protected by the channels of safety barriers

what is the essential difference between isolators and isolated safety barriers

isolators:

are used to adjust and isolate various signals of field instruments and convert them into standard signals accepted by computers, DCS, PLC, etc. or special signals specified by users. A device, such as a relay, used to electrically isolate telecontrol equipment from operating equipment

isolated safety barrier:

the associated equipment of intrinsically safe explosion-proof instruments and meters will not affect the function of the measurement system under normal conditions. It is set at one side of the safe place. When the intrinsically safe explosion-proof system fails, it can limit the energy (electric energy) entering the dangerous place within the safe value, so as to ensure the safety of on-site production

it can be seen from the above that the essential difference between the isolator and the isolated safety barrier is that the rest are uncoated cultural paper; Coated paper, household paper, paper and special paper have poor recyclability. Whether they are explosion-proof or not, i.e. different safety factors

attention to the use of safety barriers

first, pay attention to the capacitive reactance and inductive reactance of cables and field equipment. Intrinsically safe explosion-proof is the system explosion-proof. In addition to the required explosion-proof level of safety barriers, the energy storage of cables and field equipment is also a key issue. Especially after parameter certification replaces system certification, engineers should pay special attention to this problem

second, attention should be paid to intrinsically safe grounding. Zener safety barriers need intrinsically safe grounding, and the grounding resistance should be less than 1

third, intrinsically safe cables and non intrinsically safe cables shall be laid separately in different trunking. It shall be clearly marked

fourth, pay attention to power off during replacement

there are basically two types of isolated safety barriers: safety barriers at the detection end and safety barriers at the operation end. The safety barrier at the detection end is used together with the two-wire transmitter; The safety barrier at the operating end is used together with the electric converter or electric valve. There are also isolated safety barriers of signal input and other types

because the isolated safety barrier adopts measures such as voltage limiting, current limiting and isolation, it can not only prevent dangerous energy from entering the dangerous site from the intrinsically safe terminal, improve the intrinsically safe explosion-proof performance of the system, but also increase the anti-interference ability of the system, and greatly improve the reliability of system operation