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

1.Common Faults and Diagnostic Measures1.1 Transformer Oil Leakage1.1.1 Oil Leakage from Tank Weld SeamsFor oil leakage at flat joints, direct welding is applicable. For leakage at corners or joints reinforced with stiffeners, the exact leakage point is often difficult to locate, and re-leakage may occur after welding due to internal stress. For such cases, repair welding with an added iron plate is recommended: for two-surface joints, the iron plate can be cut into a spindle shape for welding;

Currently, the company operates two electric arc furnace (EAF) transformers. The secondary voltage ranges from 121 V to 260 V, with a rated current of 504 A / 12,213 A. The high-voltage side has a total of eight tap positions, utilizing motor-driven off-circuit voltage regulation. The equipment is equipped with a reactor of corresponding capacity, connected in series to designated taps on the high-voltage side. These transformers have been in operation for over 20 years. Throughout this period,

Prior to the 1960s, dry-type transformers primarily employed Class B insulation in open-ventilated designs, with the product model designated as SG. At that time, foil windings were not yet available, so low-voltage coils were typically constructed using multi-strand conductors in layered or spiral configurations, while high-voltage coils adopted a disc-type design. The conductors used were either double glass-fiber-wrapped wires or single glass-fiber-wrapped wires with alkyd enamel coating.Most

A 25 MVA electric arc furnace transformer at a certain company is an equipment imported from the former Soviet Union. It consists of three single-phase transformers, each rated at 8.333 MVA, with a connection group of D,d0. The primary voltage is 10 kV, and the secondary voltage ranges from 140 to 230.4 V. The tap-changing method is on-load tap changing with 21 steps (steps 11, 12, and 13 are combined as one step, totaling 23 positions). Each phase can be regulated independently, allowing separa

Magnetizing inrush current in electric arc furnace transformers is a problem that troubles many electrical engineers. So, why does magnetizing inrush current occur in arc furnace transformers? First, let's understand what magnetizing inrush current is.Magnetizing inrush current refers to the transient current generated in the secondary winding of an arc furnace transformer due to core saturation, increased magnetic field strength, and other factors. This phenomenon is very common during the oper

An electric arc furnace is a device that melts metal using the high temperature generated by an electric arc. It converts electrical energy into thermal energy through a transformer, then transfers the heat via the arc to the furnace charge, causing it to melt. When the arc furnace starts operating, the transformer load increases suddenly, leading to a drop in grid voltage. Additionally, due to the operational characteristics of the arc furnace, the load continues to rise over a period of time,

A HKSSPZ-6300/110 electric arc furnace transformer has the following basic parameters:Rated capacity S = 6300 kVA, primary voltage U₁ = 110 kV, secondary voltage U₂ = 110–160 V, vector group YNd11, with both low-voltage winding ends (start and finish) brought out, and equipped with 13-step on-load tap changing. Insulation levels: HV/HV neutral/LV, LI480AC200 / LI325AC140 / AC5.The transformer uses a dual-core series voltage regulation design, with an "8"-shaped low-voltage winding conf

On the morning of January 1st at 9:00 AM, the Transformer Work Zone of the Electrical Maintenance Department received an emergency repair task: a 40,000 KVA electric arc furnace transformer at a steel plant had failed and needed replacement. As a critical piece of equipment in steelmaking, the furnace transformer directly impacts the output of upstream and downstream production lines. This replacement task was urgent, challenging, and technically demanding. Under the guidance and strong support

Feeder Automation (FA) and Under-Frequency Load Shedding (UFLS) are two critical protection and control mechanisms in power systems. While both aim to ensure safe and stable system operation, they carry potential conflicts in logic and timing that require careful coordination.Feeder Automation (FA): Primarily addresses local feeder faults (e.g., short circuits, ground faults) in distribution networks. Its objective is to quickly locate and isolate faulted sections and restore power to non-faulte

1 Failure Mechanisms of Power CapacitorsA power capacitor primarily consists of a housing, capacitor core, insulating medium, and terminal structure. The housing is typically made of thin steel or stainless steel, with bushings welded to the cover. The capacitor core is wound from polypropylene film and aluminum foil (electrodes), and the interior of the housing is filled with liquid dielectric for insulation and heat dissipation.As a fully sealed device, common failure types of power capacitors