Generator 100% stator earth fault protection overcomes traditional coverage limitations by combining two complementary methods. The third-harmonic voltage principle monitors the neutral-to-terminal voltage ratio to detect faults near the neutral, triggering when this ratio falls below a typical threshold of 0.3-0.5. Simultaneously, the low-frequency injection method introduces a 20Hz signal to measure insulation resistance across the entire winding, operating if resistance drops below pre-set thresholds (typically 1-5 kΩ). This dual approach ensures complete stator coverage without dead zones, provides high sensitivity for kΩ-range faults, and offers redundancy. Protection settings are derived from security margins applied to measured normal operating parameters, including harmonic voltage ratios and maximum unbalanced voltage, making it essential for large generator security.

Zero-sequence voltage protection is a vital protection scheme in power systems specifically designed for ground faults, particularly single-phase-to-ground faults. It is widely employed in systems with an ungrounded neutral, a neutral grounded via an arc-suppression coil (Petersen coil), or a low-resistance grounded neutral. The following provides a detailed explanation from three aspects: principle, function, and setting calculation.

Instantaneous Overcurrent Protection (IOCP) is a protection scheme used in power systems to rapidly clear short-circuit faults. Its defining feature is zero intentional time delay (or minimal delay), with typical operating times of 20–50 ms, complying with IEC 60255-151 (Overcurrent Protection Standards) and IEEE C37.91 (Guide for Protection Relay Applications).

Modbus, IEC 60870-5-103, IEC 60870-5-104, and IEC 61850 are widely used communication protocols in the fields of power systems and industrial automation. They exhibit significant differences in design objectives, architecture, data models, and application scenarios. Below is a detailed comparative analysis of them.

Configuration Principles for Motor Protection Systems​

Prevent uncontrolled reclosing of breakers by the Automatic Reclosing (ARC) function following Automatic Bus Transfer (ABT) operation.

What are the differences between auto-reclosing and three-phase single-shot reclosing in line protection relays? Let's briefly compare them in terms of functionality and application scenarios.

This page introduces the function of automatic reclosing, the working principle of automatic reclosing relays, and the operating procedures. For more information, please log in to view.

Generator differential protection is one of the most critical primary protections in generator relaying systems. Its core function is to rapidly and reliably clear internal short-circuit faults in generators, preventing severe equipment damag

In this article, we explore the ​working principle of generator differential protection, its key components, and why it is critical for power system reliability.