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

1 Basic Operation RequirementsThe technical parameters of current transformers shall meet the actual operation needs. Carefully check the nameplate of the current transformer to confirm whether its technical parameters meet the requirements. Current transformers for metering must be selected with rated loads and accuracy classes that meet the requirements in accordance with relevant metering standards. The actual load connected to the secondary winding of the current transformer shall be within

Hey everyone, I'm Felix, and I've been working in the power system field for 10 years. From following senior engineers on-site to leading teams handling various substation equipment failures, I’ve worked with many types of current transformers (CTs), especially those used in air insulated switchgear (AIS).Although this type of equipment is relatively simple in structure and easy to maintain, it still experiences frequent issues during actual operation. Today, I’ll share my ha

1. IntroductionFrequent occurrences of PT burnout and primary - side fuse melting in combined transformers lead to inaccurate energy meter measurement and seriously threaten the safe operation of the power grid. This paper focuses on the repeated PT damage and fuse melting issues of a 35 kV combined transformer, investigates the fault causes, proposes solutions, and recovers the incorrect electricity quantity through correction coefficients. This effectively reduces grid losses and mitigates ser

Voltage transformers (PTs) consist of iron cores and winding coils, working similarly to transformers but with small capacity. They convert high voltage to low voltage for protection, measurement and metering devices, widely used in plants/stations. Classified by insulation: dry - type (≤6 kV), cast - type (indoor 3 - 35 kV), oil - immersed (outdoor ≥35 kV), and SF₆ gas - filled (for combined appliances).During substation operation, accidents from PT electromagnetic resonance or in

Hey everyone, I’m Oliver, and I’ve been working in current transformer (CT) testing for 8 years.From running around with test equipment on site to now leading full inspection teams, I’ve seen how thousands of outdoor CTs go through a whole series of tests — like going through a military training camp — before they can finally be put into service.A few days ago, a friend asked me: “Oliver, our factory just produced a new batch of outdoor

1. Research Reasons and Background1.1 Importance of Current TransformersCurrent transformers play the role of current transformation and electrical isolation. They convert the large current of the primary system into a proportional small secondary current, which is supplied to measuring instruments, relay protection, and automatic devices. In the power system, the role of current transformers is irreplaceable and directly plays a key role in the safe and stable operation of the power grid.1.2 Ha

1. Accident Overview1.1 Structure and Connection of 35kV GIS Switchgear Voltage TransformerThe ZX2 gas-insulated double-bus switchgear, manufactured in March 2011 and officially put into operation in July 2012, is configured with two groups of bus voltage transformers (PTs) for each bus section. The two PT groups of the same bus section are designed in one switchgear cabinet with a width of 600 mm. The three-phase PTs are arranged in a triangular formation at the bottom of the cabinet.The PTs ar

1. Accident OverviewA newly - built 110kV substation’s GIS exploded during commissioning due to a PT secondary circuit short - circuit. Though the cause was simple, consequences were severe, warranting reflection.2. Accident ProcessOn the power - transmission day: The upper - level power supply charged the 110kV GIS (a combined appliance). 20s after closing the incoming switch and first live - impacting the 110kV bus, white smoke emerged between the PT compartment and control cabinet.

I'm Oliver, with 8 years of experience in current transformer testing. These are all practical experiences, shared with you1 Maintenance of Current TransformersHaving been in the business of current transformer testing for 8 years, I know a thing or two about their maintenance! The maintenance of current transformers is divided into minor repairs, intermediate repairs, and major overhauls.Minor repairs mainly involve opening the cover (if necessary) and changing the oil, usually carried out once

Gas - insulated switchgear (GIS) , often called “SF6 combined electrical apparatus”, is widely used in power systems for its high reliability, small footprint, low noise, and low loss. It encloses high - voltage devices like circuit breakers, fast grounding switches, current transformers, and busbars in a grounded metal shell filled withSF6gas. Each device sits in a separate gas chamber with different pressures. The CT terminal block divides gas chambers, connects components,