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

Why Do Substations Use Stones, Gravel, Pebbles, and Crushed Rock?In substations, equipment such as power and distribution transformers, transmission lines, voltage transformers, current transformers, and disconnect switches all require grounding. Beyond grounding, we will now explore in depth why gravel and crushed stone are commonly used in substations. Though they appear ordinary, these stones play a critical safety and functional role.In substation grounding design—especially when multiple gr

Why Does the Transformer Core Need to Be Grounded?During operation, the transformer core, along with the metal structures, parts, and components that fix the core and windings, are all situated in a strong electric field. Under the influence of this electric field, they acquire a relatively high potential with respect to ground. If the core is not grounded, a potential difference will exist between the core and the grounded clamping structures and tank, which may lead to intermittent discharge.I

I. What is a Neutral Point?In transformers and generators, the neutral point is a specific point in the winding where the absolute voltage between this point and each external terminal is equal. In the diagram below, pointOrepresents the neutral point.II. Why Does the Neutral Point Need Grounding?The electrical connection method between the neutral point and earth in a three-phase AC power system is called theneutral grounding method. This grounding method directly affects:The safety, reliabilit

What is a Rectifier Transformer?"Power conversion" is a general term encompassing rectification, inversion, and frequency conversion, with rectification being the most widely used among them. Rectifier equipment converts input AC power into DC output through rectification and filtering. A rectifier transformer serves as the power supply transformer for such rectifier equipment. In industrial applications, most DC power supplies are obtained by combining a rectifier transformer with rectifier equ

A Brief Discussion on the Selection of Grounding Transformers in Boost StationsThe grounding transformer, commonly referred to as "grounding transformer," operates under the condition of being no-load during normal grid operation and overloaded during short-circuit faults. According to the difference in filling medium, common types can be divided into oil-immersed and dry-type; according to phase number, they can be classified into three-phase and single-phase grounding transformers. The groundi

Impact of DC Bias in Transformers at Renewable Energy Stations Near UHVDC Grounding ElectrodesWhen the grounding electrode of an Ultra-High-Voltage Direct Current (UHVDC) transmission system is located close to a renewable energy power station, the return current flowing through the earth can cause a rise in ground potential around the electrode area. This ground potential rise leads to a shift in the neutral-point potential of nearby power transformers, inducing DC bias (or DC offset) in their

1.Definition and Function1.1 Role of the Generator Circuit BreakerThe Generator Circuit Breaker (GCB) is a controllable disconnect point located between the generator and the step-up transformer, serving as an interface between the generator and the power grid. Its primary functions include isolating generator-side faults and enabling operational control during generator synchronization and grid connection. The operating principle of a GCB is not significantly different from that of a standard c

1.Transformer Maintenance and Inspection Open the low-voltage (LV) circuit breaker of the transformer under maintenance, remove the control power fuse, and hang a “Do Not Close” warning sign on the switch handle. Open the high-voltage (HV) circuit breaker of the transformer under maintenance, close the grounding switch, fully discharge the transformer, lock the HV switchgear, and hang a “Do Not Close” warning sign on the switch handle. For dry-type transformer maintenance: first clean the porcel

In practical work, insulation resistance of distribution transformers is generally measured twice: the insulation resistance between thehigh-voltage (HV) windingand thelow-voltage (LV) winding plus the transformer tank, and the insulation resistance between theLV windingand theHV winding plus the transformer tank.If both measurements yield acceptable values, it indicates that the insulation among the HV winding, LV winding, and transformer tank is qualified. If either measurement fails, pairwise

1.Noise Mitigation for Ground-Level Independent Transformer RoomsMitigation Strategy:First, conduct a power-off inspection and maintenance of the transformer, including replacing aged insulating oil, checking and tightening all fasteners, and cleaning dust from the unit.Second, reinforce the transformer foundation or install vibration isolation devices—such as rubber pads or spring isolators—selected based on the severity of vibration.Finally, strengthen sound insulation at weak points of the ro