The electrical control system is generally called the secondary control circuit of the electrical equipment. Different equipment has different control loops, and the control method of high-voltage electrical equipment and low-voltage electrical equipment is also different. In order to ensure the reliability and safety of the primary equipment operation, a number of auxiliary electrical equipments are required to serve them, and a combination of several electrical components capable of achieving a certain control function is called a control loop or a secondary loop. These devices must have the following features:
(1) Automatic control function. The volume of high-voltage and high-current switchgear is very large. Generally, operating systems are used to control the points and closings. In particular, when the equipment fails, it is necessary to switch off the circuit automatically, and a set of automatic control electrical equipment is required. Automatic control of power supply equipment.
(2) Protection function. Electrical equipment and lines will malfunction in the course of operation, the current (or voltage) will exceed the scope and limits of the equipment and the line allows work, which requires a set of detection of these fault signals and automatic adjustment of the equipment and lines (disconnected, Switching, etc.) protection devices.
(3) monitoring function. Electricity is invisible to the eyes. Whether a device is powered or off, and it cannot be distinguished from the outside, it is necessary to set various audiovisual signals, such as lighting and sound, to perform electrical monitoring on the primary device.
(4) Measurement function. Lights and sound signals can only qualitatively indicate the working status of the equipment (electricity or power failure). If you want to quantitatively know the working conditions of electrical equipment, you need to have a variety of instrument measuring equipment, measuring various parameters of the circuit, such as voltage , current, frequency, and power size.
In the operation and monitoring of equipment, most of the traditional operating components, control devices, instruments, and signals can be replaced by computer control systems and electronic components, but there is still a certain range of applications in small devices and locally controlled circuits. . This is also the basis for the circuit to realize the automatic control of the microcomputer.
The basic circuit of a commonly used control circuit composed of electrical systems consists of the following components.
(1) Power supply circuit. Power supply circuit power supply AC380V and 220V and many other.
(2) Protection circuit. The protection (auxiliary) circuit has a variety of operating power sources such as single-phase 220, 36V or DC 220, 24V, etc. It protects electrical equipment and lines from short-circuit, overload and voltage loss, and is protected by fuses, thermal relays, and loss-voltage coils. , rectifier components and voltage regulator components such as protection components.
(3) Signal loop. The circuit that can timely reflect or display the normal and abnormal working status information of equipment and lines, such as different color signal lamps, different sound audio equipment, etc.
(4) Automatic and manual directions. In order to improve work efficiency, electrical equipment generally has automatic links. However, in the process of installation, commissioning and emergency handling, manual links must also be set up in the control lines, and automatic and manual conversions can be achieved through combination switches or transfer switches.
(5) brake parking circuit. Cut off the circuit power supply, and take some braking measures to make the motor quickly stop the control link, such as energy consumption braking, power supply reverse braking, reverse pull braking and regenerative braking.
(6) Self-locking and blocking. After the start button is released, the circuit remains energized, and the electrical link in which the electrical equipment can continue to work is called the self-locking link. For example, the contactor's moving contact is connected in series with the coil circuit. Two or more than two electrical devices and components, in order to ensure the safety and reliability of the operation of the equipment, only one power-activated start, and the other can not start the protection of power links, called the lock-out link. For example, the two movable contacts of the two contactors are respectively connected in series in the other coil circuit.
(1) Automatic control function. The volume of high-voltage and high-current switchgear is very large. Generally, operating systems are used to control the points and closings. In particular, when the equipment fails, it is necessary to switch off the circuit automatically, and a set of automatic control electrical equipment is required. Automatic control of power supply equipment.
(2) Protection function. Electrical equipment and lines will malfunction in the course of operation, the current (or voltage) will exceed the scope and limits of the equipment and the line allows work, which requires a set of detection of these fault signals and automatic adjustment of the equipment and lines (disconnected, Switching, etc.) protection devices.
(3) monitoring function. Electricity is invisible to the eyes. Whether a device is powered or off, and it cannot be distinguished from the outside, it is necessary to set various audiovisual signals, such as lighting and sound, to perform electrical monitoring on the primary device.
(4) Measurement function. Lights and sound signals can only qualitatively indicate the working status of the equipment (electricity or power failure). If you want to quantitatively know the working conditions of electrical equipment, you need to have a variety of instrument measuring equipment, measuring various parameters of the circuit, such as voltage , current, frequency, and power size.
In the operation and monitoring of equipment, most of the traditional operating components, control devices, instruments, and signals can be replaced by computer control systems and electronic components, but there is still a certain range of applications in small devices and locally controlled circuits. . This is also the basis for the circuit to realize the automatic control of the microcomputer.
The basic circuit of a commonly used control circuit composed of electrical systems consists of the following components.
(1) Power supply circuit. Power supply circuit power supply AC380V and 220V and many other.
(2) Protection circuit. The protection (auxiliary) circuit has a variety of operating power sources such as single-phase 220, 36V or DC 220, 24V, etc. It protects electrical equipment and lines from short-circuit, overload and voltage loss, and is protected by fuses, thermal relays, and loss-voltage coils. , rectifier components and voltage regulator components such as protection components.
(3) Signal loop. The circuit that can timely reflect or display the normal and abnormal working status information of equipment and lines, such as different color signal lamps, different sound audio equipment, etc.
(4) Automatic and manual directions. In order to improve work efficiency, electrical equipment generally has automatic links. However, in the process of installation, commissioning and emergency handling, manual links must also be set up in the control lines, and automatic and manual conversions can be achieved through combination switches or transfer switches.
(5) brake parking circuit. Cut off the circuit power supply, and take some braking measures to make the motor quickly stop the control link, such as energy consumption braking, power supply reverse braking, reverse pull braking and regenerative braking.
(6) Self-locking and blocking. After the start button is released, the circuit remains energized, and the electrical link in which the electrical equipment can continue to work is called the self-locking link. For example, the contactor's moving contact is connected in series with the coil circuit. Two or more than two electrical devices and components, in order to ensure the safety and reliability of the operation of the equipment, only one power-activated start, and the other can not start the protection of power links, called the lock-out link. For example, the two movable contacts of the two contactors are respectively connected in series in the other coil circuit.