Latin America HS code compliance tips

List of the contents of this article:

• 1, What is the low-pressure water supply system of firefighting
• 2, Illustrate the difference between low-voltage, high-pressure and temporary high-pressure water supply systems, eliminate knowledge points, it is recommended to collect
• 3, What are the test equipment for voltage, frequency, insulation resistance and grounding resistance in the low-voltage power distribution system?..
• 4、 In the power system, what standards are the classification of low-voltage systems and high-voltage systems?
• 5, What are the three types of low-voltage power supply and distribution systems

What is the low-pressure water supply system of firefighting

1. Low-voltage firefighting water supply system: can meet the needs of on-board or hand-lifted mobile firefighting water The water supply system of the working pressure and flow rate required for pumps and other water.

2. The pressure in the pipe network of the low-pressure fire water supply system is low. The pressure required by the water gun when extinguishing the fire on the fire is formed by the pressure of the fire truck or other mobile fire water pump. When this water supply system is adopted, the pressure of its pipe network ensures that the water pressure of the fire hydrant, which is the least beneficial when extinguishing the fire, is not less than 10 meters of water column.

3. That is a voltage-stabilizing system, which is usually maintained by the top-top voltage-stabilizing system, and in the early stage of firefightingPressurize the water supply to the fire hydrant or sprinkler system. The above-top fire pool only uses fire water for 10 minutes. However, when the pressure of the pipe network is lower than the set value, the main pump needs to be started immediately to pressurize the main pump, which does not mean that it must wait 10 minutes to start the main pump.

4. Yes, low-pressure fire water supply system. It refers to the low water pressure (generally 0.1~0.3MPa) in the pipe network, and the pressure required by the water gun when extinguishing the fire is supplied by the fire truck or mobile fire pump, but it must be pointed out that 0.1MPa is the terminal pressure of the pipe.

Illustrate the difference between low-voltage, high-pressure and temporary high-pressure water supply systems, one-dispel knowledge points, It is recommended to collect

Temporary high-pressure fire water supply system: The most unfavorable water pressure and flow rate in the fire water supply network cannot meet the needs of fire extinguishing, and the system is equipped with a fire pump fire water supply system. Start the fire pump when extinguishing the fire, so that the least favorable water pressure and flow rate in the pipe network meet the requirements of extinguishing the fire.

Fire water pressure, the outdoor fire water supply system is divided into high-pressure fire water supply system, temporary high-pressure fire water supply system and low-pressure fire water supply system according to the requirements of fire water pressure.

High-pressure fire water supply system. The high-pressure fire water supply system always maintains sufficient fire water consumption and water pressure in the pipe network. There is no need to use fire trucks or other mobile fire water pumps to pressurize the fire site. The water belt and water gun can be directly connected from the fire hydrant to extinguish the fire.

I) High-pressure fire water supply system High-pressure fire water supply system refers to the pressure and flow rate required for fire extinguishing in the pipe network. When fighting a fire, it does not need to start the fire pump to pressurify and directly use fire extinguishing equipment.

Low pressure is the municipal water supply, using municipal pressure, generally only 0.2MPa, high pressure is divided into normal high pressure and temporary high pressure, normal high pressure, as the name implies, means that the pressure is always guaranteed at a high value.

What are the test equipment for voltage, frequency, insulation resistance and grounding resistance in the low-voltage power distribution system...

1. For the plate-installed measurement of voltage and current, a voltmeter and ammeter can be used to connect with voltage transformers and current transformers respectively. Voltage transformers are divided into two categories according to the principle: electromagnetic induction type and capacitor voltage division type. The electromagnetic induction type is mostly used for various voltage levels of 220kV and below.

2. Insulation resistance tester: used to test the insulation resistance of circuits or electrical equipment. Ground wire resistance tester: used to test the resistance of the ground wire to verify whether the grounding system is installed and running correctly. Multimeter: a general tester that can measure parameters such as current, voltage, resistance, capacity and conductivity.

3. The megohmmeter is mainly used to check the insulation resistance of electrical equipment, household appliances or electrical lines to the ground and between phases.According to different products, the megohmmeter selects different voltage levels such as 100V, 250V, 500V, 1000V, etc. to measure its insulation resistance value.

4. Megohmmeter, megohmmeter is also known as insulation meter, high-voltage insulation resistance tester, insulation resistance measuring instrument, insulation characteristic tester, etc. It is mainly used to check the insulation resistance of electrical equipment, household appliances or electrical lines to the ground and between phases.

5. The measurement of the insulation resistance of the line or equipment is measured by a megohmmeter. The megohmmeter is an instrument used to measure the insulation resistance and high resistance of the measured equipment. It consists of a hand crank generator, a meter head and three wiring poles (i.e. L: line end, E: grounding end, G: shielding end).

In the power system, what are the criteria for low-voltage systems and high-voltage systems?

The power system rarely uses the words "high-voltage system" and "low-voltage system", but clearly stipulates that ground voltages above 250V are high-voltage equipment, and 250V and below are low-voltage equipment. I think 250V should be used to define the high and low voltage system, otherwise there will be contradictions.

The voltage grade is generally divided into: safe voltage (usually below 36V). Low voltage (also divided into 220V and 380V). High voltage (10KV-220KV). Ultra-high voltage 330KV-750KV. Ultra-high voltage 1000KV AC, ±800KV DC or more.

The power system actually has five voltage levels: 500kV; 220kV;110kV; 35kV; (20kV) 10kV According to the provisions of power safety regulations, the voltage is mainly divided into high-voltage and low-voltage, bounded by 1000V, which is equal to high voltage above 1000V and low voltage below 1000V.

What are the three types of low-voltage power supply and distribution systems

1. Comparison of low-voltage power distribution systems TN, TT and IT According to the definition of the current national standard "Low-voltage Power Distribution Design Specification" (GB50054), the low-voltage power distribution Electrical systems are divided into three forms, namely TN, TT and IT.

2. There are three commonly used low-voltage power distribution methods. According to the terminology concepts of various protective grounding methods stipulated by iec, the low-voltage power distribution system is called tt system, tn system and it system according to different grounding methods.Among them, the tn system is divided into tn-c, tn-s and tn-c-s system.

3. The following is a brief introduction to various power supply systems.

4. Power supply mode of low-voltage power distribution system Low-voltage power distribution system can be divided into: IT system, TT system and TN system according to the form of protective grounding.

5. The power supply and distribution system is composed of high and low voltage distribution lines, substations (including distribution stations) and electrical equipment. High and low voltage power distribution lines: the line that sends electricity from the step-down substation to the power distribution transformer or the power from the power distribution substation to the power-using unit.

6. The three-phase three-wire system adopts a low-voltage power supply system, voltage, frequency and phase. Three-phase alternating current is a power system composed of three alternating current circuits with the same frequency, equal potential amplitude and 120° difference in phase difference.