As a key power distribution equipment, the safe operation of a compact substation relies on reliable grounding measures. People often wonder: Why is the grounding resistance of a compact substation generally required to be no more than 4Ω? Behind this value, there are rigorous technical bases and application scenario restrictions. In fact, the requirement of ≤4Ω is not mandatory in all cases. It mainly applies to scenarios where the high - voltage system adopts "ungrounded", "reso

In modern power systems, DC electronic current transformers play a crucial role. They are not only used for high-precision current measurement but also serve as key tools for grid optimization, fault detection, and energy management. With the rapid development of high-voltage direct current (HVDC) transmission technology and its widespread deployment globally, the performance requirements for DC current transformers have become increasingly stringent, especially in terms of measurement accuracy

1 Performance AdvantagesIn recent years, electronic current transformers (ECTs) have emerged as a key industry trend. National standards classify them into two types: Active Optical Current Transformers (AOCTs, active hybrid type) and Optical Current Transformers (OCTs, passive optical type). Active hybrid ECTs use low-power electromagnetic transformers and Rogowski coils as core sensing elements (Figure 1).Rogowski coils outperform traditional sensors with non-saturation and wide dynamic ranges

In real-world engineering projects, selecting and installing 35kV combined instrument transformers isn't just a matter of "buying and installing" — it requires a comprehensive evaluation of many factors, such as environmental conditions, equipment performance, and maintenance convenience. Only by taking all these aspects into account can we ensure that the equipment runs safely and stably for a long time under specific conditions.1. Oil-Immersed vs. Dry-Type Transformers — Which One

The installation quality of combined instrument transformers directly affects whether they can operate safely and stably. Therefore, during the installation process, several key aspects must not be overlooked — such as foundation construction, grounding, sealing checks, testing and commissioning, as well as secondary wiring. Below, I’ll explain these points in a more conversational way.1. Foundation Construction Must Be Solid, Especially in Plateau AreasAlthough a combined instrument

1 Principle and Role of Electronic Current Transformers1.1 Working Principle of ECTAn Electronic Current Transformer (ECT) is a key device for managing safe power system operations, converting large currents into manageable small-current signals for measurement and control. Unlike traditional transformers (relying on direct magnetic field interaction between primary and secondary windings), ECTs use sensors (e.g., Hall effect sensors) to detect magnetic field changes from the primary winding. Th

Traditional power transformers face inherent issues due to their sensors. Critically, they are vital for power plant monitoring, control, and protection (e.g., fault recording, safety control). However, large electrical energy transmission via information carriers and the lack of digital signal output from digital systems complicate secondary communication. Complex secondary wiring compensates for microcomputers’ high reliability, streamlining protection and secondary devices. This innovat

Hi everyone, I’m Oliver, and I’ve been working in the instrument transformer industry for almost eight years now. From a complete newbie to someone who can now handle things independently, I’ve participated in dozens of combined instrument transformer inspections over the years.Today, I’d like to share with you: What tests must a qualified combined instrument transformer go through before leaving the factory or being put into operation? After all, it's a very critical pie

Applications and Trends of 35kV Combined Instrument Transformers – From Echo’s PerspectiveHey everyone! My name is Echo, and I’ve been working in the field of instrument transformers for 12 years now. Today, I’d like to share some insights about the applications and future trends of 35kV combined instrument transformers. Hope this can give you a glimpse into this fascinating industry.Application Scenarios: More Than Just Metering ToolsFirst off, let's talk about applicati

1 Measurement Principle of Combined Electronic Transformers1.1 Voltage Measurement PrincipleElectronic transformers measure voltage using the capacitive voltage division method. Since the voltage across a capacitor cannot change abruptly, the secondary voltage obtained directly through capacitive voltage division has poor transient response and low measurement accuracy. To improve the measurement accuracy, a precision sampling resistor is connected in parallel across the low-voltage capacitor. I