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

Transformers are critical components in power systems, and various failure modes can affect their operation. Timely identification and resolution of these failure modes are essential to prevent costly downtime and ensure system reliability. Below are some common transformer failure modes, along with methods to identify and address them: Insulation FailureIdentification: Insulation failure leads to decreased insulation resistance, which can be detected through insulation resistance testing (megge

Most DC molded-case circuit breakers use natural air arc extinction, and there are typically two arc extinguishing methods: one is conventional opening and closing, where the contacts axially stretch the arc, while the conductive circuit generates a magnetic field that bends and elongates the arc, pulling it lengthwise perpendicular to the arc axis. This not only increases the arc length but also induces lateral motion, enabling air cooling to achieve arc extinction.The other method involves the

The arc extinguishing system of a DC circuit breaker is crucial for the safe operation of equipment, as the arc generated during current interruption can damage contacts and compromise insulation.In AC systems, the current naturally passes through zero twice per cycle, and AC circuit breakers take full advantage of these zero-crossing points to extinguish the arc.However, DC systems lack natural current zero crossings, making arc extinction significantly more difficult for DC circuit breakers. T

1 Technical Challenges1.1Stability of Device ParallelingIn practical applications, the current-carrying capacity of a single power electronic device is relatively limited. To meet high-current requirements, multiple devices are often connected in parallel. However, parameter variations between devices—such as slight differences in on-resistance and threshold voltage—can cause uneven current distribution during parallel operation. During switching transients, parasitic inductance and capacitance

First of all, it must be clarified: AC circuit breakers must not be used to replace DC circuit breakers in DC circuits!Due to differences in arc generation and extinction processes between AC and DC, AC and DC circuit breakers with the same rated values do not have identical capabilities when interrupting DC power. Using AC circuit breakers in place of DC ones, or mixing AC and DC breakers, is one of the main causes of protection miscoordination and unintended upstream tripping.Circuit breakers

For a 24V switch-mode power supply branch, I used a single-pole DC circuit breaker, with the negative pole subjected to equipotential bonding (previously, I even directly used AC breakers as substitutes—the main difference being arc-extinguishing performance, but how significant can the arc be in a few-amp low-current short circuit?).During a design review, an expert stated that DC circuit breakers must be bipolar, arguing that DC has positive and negative poles, unlike AC!I'm puzzled—where is t

Fully electric commercial vessels are becoming increasingly popular, with DC power systems being the preferred choice for onboard power distribution due to their ability to handle high power flows within limited space at higher system efficiency and lower lifecycle costs.Commercial vessels equipped with onboard DC grids have proven capable of operating at peak energy efficiency while minimizing emissions. This results in significant power savings and reduced operating costs across maritime appli

1. Security Threats Facing Smart Meter Communications1.1 Physical Layer Security ThreatsPhysical layer security threats refer to factors that damage or interfere with the hardware devices and physical connections of smart meters, directly affecting their normal operation and data transmission. From the perspective of equipment damage, harsh natural environments such as lightning strikes, floods, and earthquakes can directly destroy the hardware circuits and structures of smart meters, rendering

1. Issues and Cause Analysis in Smart Electricity Meter TestingDuring the verification of smart electricity meters, inspections must be conducted on the meter’s appearance, as well as the clarity and integrity of nameplate markings. Additionally, careful checks are required for physical damage and whether the display can show digits completely. A power-on inspection is also necessary. If error codes appear on the display after power-up, faults should be identified and addressed according to the

With the continuous development of smart grids, smart electricity meters are being increasingly widely applied, and various types of operational faults in smart meters are frequently encountered in energy measurement work. This paper analyzes the causes of smart meter failures and proposes corresponding solutions, using several actual operational fault cases as examples.1. Black ScreenA black screen refers to a powered meter with no display, which is the most commonly occurring fault in field-op