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

Characteristics and Detection Devices for Single-Phase Ground Faults1. Characteristics of Single-Phase Ground FaultsCentral Alarm Signals:The warning bell rings, and the indicator lamp labeled “Ground Fault on [X] kV Bus Section [Y]” illuminates. In systems with a Petersen coil (arc suppression coil) grounding the neutral point, the “Petersen Coil Operated” indicator also lights up.Insulation Monitoring Voltmeter Indications:The voltage of the faulted phase decreases (in

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

Design Principles for Pole-Mounted Distribution Transformers(1) Location and Layout PrinciplesPole-mounted transformer platforms should be located near the load center or close to critical loads, following the principle of “small capacity, multiple locations” to facilitate equipment replacement and maintenance. For residential power supply, three-phase transformers may be installed nearby based on current demand and future growth projections.(2) Capacity Selection for Three-Phase Pole-Mounted Tr

1.Electric Shock Risk Prevention and ControlAccording to typical design standards for distribution network upgrades, the distance between the transformer’s drop-out fuse and the high-voltage terminal is 1.5 meters. If a crane is used for replacement, it is often impossible to maintain the required minimum safety clearance of 2 meters between the crane boom, lifting gear, slings, wire ropes, and the 10 kV live parts, posing a severe risk of electric shock.Control Measures:Measure 1:De-energize th

Common Faults and Causes in Routine Inspection of Distribution TransformersAs the terminal component of power transmission and distribution systems, distribution transformers play a critical role in supplying reliable electricity to end users. However, many users have limited knowledge of power equipment, and routine maintenance is often carried out without professional support. If any of the following conditions are observed during transformer operation, immediate action should be taken: Excess

Analysis of Lightning Protection Measures for Distribution TransformersTo prevent lightning surge intrusion and ensure the safe operation of distribution transformers, this paper presents applicable lightning protection measures that can effectively enhance their lightning withstand capability.1. Lightning Protection Measures for Distribution Transformers1.1 Install surge arresters on the high-voltage (HV) side of the distribution transformer.According to SDJ7–79 Technical Code for Overvol

1. Design Requirements to Improve Transformer Short-Circuit Withstand CapabilityDistribution transformers should be designed to withstand symmetrical short-circuit currents (thermal stability current) at 1.1 times the current under the most unfavorable three-phase short-circuit conditions. The peak short-circuit current (dynamic stability current) should be designed for 1.05 times the current when short-circuit occurs at the instant of zero terminal voltage (maximum peak current factor). Based o

Impulse Testing of New or Overhauled Transformers Before CommissioningDo you know why new or overhauled transformers must undergo impulse testing before official commissioning? This testing verifies whether the transformer's insulation strength can withstand the impact of full voltage or switching overvoltages.The principle behind impulse testing relates to what happens when an unloaded transformer is disconnected. The circuit breaker interrupts a small magnetizing current, potentially forcing c

Lightning Protection for Distribution Transformers: Arrester Installation Position AnalysisIn China's economic development, the power system holds an extremely important position. Transformers, as devices utilizing electromagnetic induction to convert AC voltage and current, represent a crucial component of the power system. Lightning damage to distribution transformers is quite common, particularly significant in humid tropical areas with frequent lightning activity. A research team has propose