In the automatic fire alarm system based on bus, it often happens that the bus in a certain area fails (such as short circuit), which leads to the failure of the whole alarm system. The function of isolator is to isolate the faulty bus part from the whole system when the bus fails, so as to ensure that other parts of the system can work normally, and it is also convenient to determine the faulty bus part. When the bus of the faulty part is repaired, the isolator can resume its work by itself and reintegrate the isolated part into the system.
If the system is large or there are isolators in the budget and design drawings, use isolators. It does not say under what circumstances it is not allowed to be used, but the number of isolators in a loop is limited. Generally, in the drawing design of the design institute, the vibration isolator is placed in the protected area (or loop).
In the fire protection design, where there is an automatic fire alarm system, a fire alarm controller needs to be set. For the places where an automatic fire alarm system needs to be set, please refer to Article11in Code for Fire Protection of Building Design:
1 1.4. 1 The following places shall be equipped with automatic fire alarm system:
1 large and medium-sized computer room and its control room, recording medium library, rooms for machinery, instruments and equipment with high fire risk, valuables warehouse and rooms with gas fire extinguishing system;
2. A warehouse for cotton, wool, silk, hemp, chemical fiber and its fabrics with an area greater than 1000 m2, and a tobacco warehouse with an area greater than 500m2 or a total construction area greater than 1000 m2;
3. Shoe-making, garment-making, toys and other factories with a construction area of over 1500m2 or a total construction area of over 3000m2;
4. Shops, exhibition buildings, financial and trade buildings and passenger and freight buildings with a construction area of over 3000m2 or a total construction area of over 6000m2;
5. Collection of books and cultural relics, each library has more than 6,543,800 books and important files;
6. Radio and television buildings, postal buildings, telecommunications buildings, urban or regional power, transportation and disaster prevention and relief command and dispatch buildings at or above the prefecture level;
7. Super-class and first-class theaters or theaters and cinemas with seats exceeding 1500, auditoriums or auditoriums with seats exceeding 2,000, and gymnasiums with seats exceeding 3,000;
Buildings for the elderly, hotels with a building area of more than 1500m2 or a total building area of more than 3000m2, ward buildings in sanatoriums, children's activity places, outpatient buildings, ward buildings and operating departments of hospitals with more than 200 beds;
9 underground and semi-underground shops with a building area of more than 500m2;
10 is set in the underground, semi-underground or above four floors of the building;
1 1 The technical interlayer with clear height greater than 2.6m and more combustible materials is located in a stuffy roof or suspended ceiling with clear height greater than 0.8m and more combustible materials.
When to use isolated inverter and non-isolated inverter, first of all, it depends on the local standards for installing inverters and power grid requirements;
Secondly, look at the size of the system where the inverter is installed;
Third, look at the cost performance and user needs.
For example, when a solar power generation system is installed below 200kW in China low-voltage distribution network, both isolated inverters and non-isolated inverters can be directly connected to the grid, and there is no clear regulation. This kind of non-isolated inverter with the same specification has the advantages of light weight, low price and high efficiency.
When to install terminal water test in fire protection design, first of all, you should understand the function of terminal water test: it is to start the fire pump, detect the water pressure of the nozzle at the most unfavorable point, and detect the working state of all parts of the alarm valve (including: pressure switch, water flow indicator, water conservancy alarm bell, etc.). )
Therefore, it is necessary to install all fire fighting systems with closed nozzles (including wet systems, dry systems and pre-action systems).
How to connect the fire-fighting short-circuit isolator only to the bus and not to the 24V power supply? Pay attention to the distinction between the incoming terminal and the outgoing terminal and the polarity of the bus. See the instructions for details. The specification requires that there should be no more than 32 devices behind the short-circuit isolator.
When do you need a cream? If you make up, you must use cream to isolate the makeup and pores on the panel, which is good for the panel ~ ~ and you can use sunscreen with SPF in summer!
What is the difference between a distribution isolator and a signal isolator? When to use signal isolators and when to use distribution isolators? There is a lot of knowledge about these! It takes several books to finish these. It can only be said briefly here: the distribution isolator is a kind of isolating switch, which is used to isolate the power supply from the electrical equipment to prevent misoperation and avoid accidents. Improper switching is only used for isolation, and it can also be a knife, air switch, circuit breaker, universal circuit breaker and so on. Signal isolator: it belongs to electronics, electricity, electronic information and communication related majors. There are many kinds of signals. In these specialties, we refer to changing current, voltage, lightning and magnetic field, including digital signals and analog signals. One: Only pure power is also a power signal with frequency and waveform, such as rectification and filtering. Two: If only signals are allowed to pass, but no current is allowed to pass, it is also a way to convert electrical signals into optical signals for data transmission. The power supply of superior and subordinate equipment is completely isolated from the power supply of superior, such as optical fiber communication. Thirdly, the optical coupling network of switching power supply, the feedback signal of power supply stabilized sampling and oscillation is transmitted by optical coupling, which reduces the failure rate and improves the safety factor.
Under what circumstances should circuit breakers and disconnectors be used? Lines or electrical equipment need short circuit protection, and overload protection needs circuit breakers.
When it is necessary to isolate the line during maintenance, it is necessary to isolate the switch.
How many wires does the fire short-circuit isolator pass through? The short-circuit isolator of the fire alarm device has only two wires, that is, the bus of the alarm circuit enters and exits, and the isolator is actually connected in series on the line of the alarm circuit.