Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

A high-voltage DC hybrid circuit breaker is a sophisticated and efficient device designed to quickly and reliably interrupt fault currents in high-voltage DC circuits. The breaker primarily consists of three components: the main branch, the energy absorption branch, and the auxiliary branch.The main branch features a fast mechanical switch (S2), which rapidly disconnects the main circuit upon detection of a fault, preventing further flow of fault current. This rapid response capability is crucia

Role of Contactors in AC and DC CircuitsA contactor is an automatic switch used to frequently connect and disconnect circuits. It is widely applied in power systems. While the basic principle of contactors is similar in both AC and DC circuits, their roles can differ slightly. Below is a detailed explanation of the role of contactors in these two types of circuits:Basic Principles of ContactorsA contactor consists of three main parts: Electromagnetic System: Includes the coil and core, used to g

The operation of a hybrid circuit breaker is divided into eight intervals, corresponding to four operational modes. These intervals and modes are as follows: Normal Mode (t0~t2):During this interval, power is transmitted seamlessly between the two sides of the circuit breaker. Breaking Mode (t2~t5):This mode is used to interrupt fault currents. The circuit breaker rapidly disconnects the faulty section to prevent further damage. Discharge Mode (t5~t6):In this interval, the voltage across the cap

The Typical Single-Line Diagram of an HVDC Transmission Scheme Using DC Side SwitchgearThe typical single-line diagram shown in the figure illustrates an HVDC transmission scheme utilizing DC side switchgear. The following switches can be identified from the diagram: NBGS – Neutral Bus Grounding Switch:This switch is typically in the open position. When closed, it firmly connects the converter's neutral line to the station ground pad. If the converter can operate in bipolar mode with b

Hybrid DC Circuit Breaker SolutionThe hybrid DC circuit breaker solution combines the excellent switching capabilities of power electronic devices (such as IGBTs) with the low-loss characteristics of mechanical switchgear. This design ensures that, unless interruption is needed, current does not flow through the semiconductors in the main circuit breaker. This is achieved through a mechanical bypass path, which consists of a super-fast disconnector (UFD) and an auxiliary commutation switch conne

Valve Hall OverviewThe valve hall is a specialized building housing the valves of a High-Voltage Direct Current (HVDC) static inverter. These valves are typically composed of thyristors, and in older plants, they may consist of mercury-arc rectifiers. The valve hall is a crucial component of the HVDC system, ensuring its safe and efficient operation.Grounding SystemThe grounding of valve hall components is ensured by highly customized grounding switches. For this purpose, two different types of

The air gap and the open circuit in a circuit are two different concepts, each with their unique definitions and roles in electrical engineering.Air GapDefinition: A gap is a non-magnetic region between two magnetic components (such as the stator and rotor) in a motor or other electrical device. This area is typically filled with air but may also contain other non-magnetic materials.Function: Magnetic Flux Regulation: The presence of a gap affects the distribution and path of magnetic flux. A la

Hybrid Circuit Breaker with IGBT Simulink Electronic InterruptionIn a hybrid circuit breaker with IGBT Simulink electronic interruption (as shown in the left figure), the fault current is diverted from the main path to the interrupter path by the IGBTs in path 1. Meanwhile, a local current zero-crossing is created by a set of IGBTs in path 2.In the right figure, the short-circuit fault current begins to flow through the circuit breaker at t1. Then, at t2 , the current is interrupted in path 1 (a

Circuit DescriptionA 12-pulse rectifier is used as the current source to provide a DC test current, while a voltage oscillation circuit provides the recovery voltage after current switching. Auxiliary breakers and spark gaps are implemented in the circuit to connect these two sources to the test object at specific intervals. The specific implementation is as follows:12-Pulse Rectifier: The rectifier is controlled to provide a DC test current to the test breaker (TB) through a smoothing reactor L

The Figure Shows the Current and Voltage Waveforms. When the DCCB (Direct Current Circuit Breaker) is in Normal Operation (Circuit Breaker S1 and Residual Current Circuit Breaker S2 are Closed, S3 is Open), the Opening Sequence Begins. The Circuit Breaker is Triggered by a Protective Relay. Here, the Relay Time is Assumed to be 2ms. After Receiving the Trip Signal, Switch S1 Starts to Operate. When It Reaches a Sufficient Distance to Withstand the Transient Voltage Applied During the Interruptio