Directional overcurrent protection is primarily used for transmission line protection, while bus protection requires fast and reliable fault clearance. Although their protection objectives differ, directional overcurrent protection can be configured with additional logic to indirectly provide bus protection.

Three-Step Current Protection​ is a classic protection scheme widely used in power systems for transmission lines and electrical equipment. It consists of ​Instantaneous Overcurrent Protection (Stage I), Time-Limited Overcurrent Protection (Stage II), and Definite-Time Overcurrent Protection (Stage III)​. Its core feature is ​graded coordination, balancing speed, selectivity, and backup protection, making it essential for power distribution and transmission networks.

Bus differential protection is a critical relay system in power systems, designed to quickly isolate bus faults with high selectivity, speed, and reliability.

Satellite time synchronization devices ensure precise, unified timing across power stations, enabling reliable protection, control, and monitoring in modern smart grids

The motor magnetic balance differential protection relay is an internal fault protection device used for medium- and high-voltage motors, detecting winding faults by comparing the current difference between the motor's input and neutral terminals.

Distance protection is a core protection method for high-voltage transmission lines, implemented using ​distance protection relays​ that determine fault location by measuring the impedance between the fault point and the protection installation point and executing tripping accordingly

A digital motor protection relay is an intelligent protection device that uses microprocessor technology to monitor and protect motors from various electrical faults.

Thermistor Motor Protection Relay​ monitors motor winding temperature in real-time using PTC/NTC thermistors, triggering protection (alarm or power cutoff) against overheating. It is suitable for critical equipment like servo and high-voltage motors, effectively preventing insulation damage and burnout failures.

Generator loss-of-excitation protection serves as a critical defense against generator excitation current failure caused by excitation system faults. As vital protection against system oscillations, terminal equipment damage, and reverse flow of reactive power during asynchronous operation.

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.