High-voltage direct current refers to a high-voltage current whose direction and time do not change periodically, but the magnitude of the current may not be fixed, and a waveform is generated. Also known as constant current. The circuit passed through is called a DC circuit, which is a closed conductive circuit composed of a DC power supply and a resistor.
1. Introduction to High-voltage direct current
High-voltage direct current means that the size (voltage level) and direction (positive and negative poles) do not change with time (relative range), such as dry batteries. Pulsating direct current means that the direction (positive and negative poles) does not change, but the magnitude changes with time. For example, we get a typical pulsating direct current after rectifying a 50Hz alternating current through a diode. The 100Hz pulsating direct current is obtained by full-wave or bridge rectification. They become smooth direct current only after being filtered (inductor or capacitor). filter effect.
2. The principle of High-voltage direct current
The circuit through which high-voltage direct current passes is called a direct current circuit, which is a closed conductive circuit composed of a direct current power supply and a resistor. In this DC-DC circuit, a constant electric field is formed. Outside the power supply, the positive charge flows from the high potential to the low potential through the resistance. In the power supply, the non-electrostatic force of the power supply overcomes the electrostatic force, and then reaches the high potential from the low potential. This cycle forms a closed circuit. current wire. Therefore, in a DC circuit, the function of the power supply is to provide a constant electromotive force that does not change with time to supplement energy for the Joule heat consumed on the resistance.
3. High-voltage direct current DC screen
The general name of DC screen is intelligent maintenance-free DC power supply screen, referred to as DC screen, and the general model is GZDW. Simply put, a DC screen is a device that provides a stable DC power supply. (When the input has 380V power supply, it is directly converted to 220V, and when there is no input (mains power and backup power), it is directly converted to battery power supply - DC 220V: in fact, it can also be said to be an industrial special emergency power supply) . The power operating power supply in power plants and substations is currently using DC power supply, which provides power for control loads and power loads, as well as DC accident lighting loads, and is the basis for control and protection of contemporary power systems. The DC screen is composed of a power distribution unit, a charging module unit, a step-down silicon chain unit, a DC feed unit, a power distribution monitoring unit, a monitoring module unit, a battery detection unit and an insulation monitoring unit. It is mainly used in small and medium-sized power plants, hydropower stations, various substations, and other users who use DC equipment (such as petrochemical, mine, railway, machine room, etc.) in the power system. , relay protection and fault lighting and other occasions.
4. High-voltage direct current DC screen technical indicators
4.1 AC measurement accuracy: ≤ 1.0% within the range of 220V and 380V±15%
4.2 DC measurement accuracy: control bus voltage: ≤ 0.5% in the range of 110V~240V, ≤ 0.5% in the range of 286V~198V charging voltage: ≤ 0.5% in the range of 286V~198V battery voltage: 12.5V±10% The range is ≤ 0.5% Control mother, charging current: ≤ 0.5% within the range of 10%Ie~100%Ie
4.3 Charging control parameters: Regulator output voltage (DC): 0 ~ 8.0V controlled (100mA)
4.4 Temperature detection: 1 battery room temperature -40°C~125°C 109 battery temperature inspections -55°C~125°C
4.5 Battery online detection: schematic diagram of 256-channel DC screen
4.6 Insulation online detection: 8~64 channels, can be customized
4.7 Branch switch state detection: 8~64 roads
4.8 Silicon Chain Control: Level 5
4.9 Fault records: 64
4.10 Relay contacts: 220V / 2A
5. High-voltage direct current DC power supply
The DC power supply has two electrodes, positive and negative. The potential of the positive electrode is high, and the potential of the negative electrode is low. When the two electrodes are connected to the circuit, a constant potential difference can be maintained between the two ends of the circuit, thereby forming an external circuit from the positive electrode to the negative electrode. negative current. A constant water flow cannot be maintained solely by the difference in water level, but a constant water level difference can be maintained by means of a water pump to continuously send water from a low place to a high place to form a steady water flow. Similar to this, the electrostatic field generated by the charge alone cannot maintain a constant current, but with the help of a DC power supply, the positive charge can be transferred from the negative electrode with a lower potential to Return to the positive electrode with higher potential through the power supply to maintain the potential difference between the two electrodes, thus forming a stable current. Therefore, a DC power supply is an energy conversion device that converts other forms of energy into electrical energy supply circuits to maintain a steady flow of current.