1. Overview

2. Parameters & Main Technical Specifications

• Voltage Rating: Operates typically on 48V or 125V DC power supply, adapting to common power distribution and substation power supply configurations.
• Protection Type: Series B differential protection, a specialized protection scheme tailored for power transformer fault identification and isolation.
• Current Measurement: Used in conjunction with Current Transformers (CTs); the differential protection current threshold requires presetting, generally set at 10% – 30% of the rated current to balance sensitivity and anti-interference performance.
• Trigger Threshold: Adjustable current threshold, which serves as the core criterion to distinguish internal transformer faults from external system faults, preventing maloperation caused by external disturbances.
• Response Time: Features ultra-fast response performance, with complete actuation completed within the millisecond level to minimize fault damage to transformers and ensure power system stability.

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3. Product Features

• High Sensitivity: Capable of detecting extremely small differential current variations, enabling rapid identification of incipient internal transformer faults that are difficult to capture by conventional protection devices, maximizing transformer protection effectiveness.
• Excellent Selectivity: Through precise current threshold setting, it can accurately differentiate between internal faults and external faults (such as load fluctuations, external short circuits), effectively eliminating maloperation risks and ensuring stable operation of the protection system.
• High Reliability: Backed by GE’s long-standing reputation for industrial-grade reliability, this relay is engineered to withstand harsh power system operating conditions, making it ideal for critical power grid infrastructure including substations and power distribution hubs.
• Collaborative Operation: Standardly paired with Current Transformers (CTs) for operation; wiring and parameter configuration must be strictly implemented in accordance with the CT transformation ratio to guarantee accurate current measurement and reliable protection actuation.

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4. Structure & Components

• Relay Unit: The core component of the relay, integrating electronic or electromagnetic contact mechanisms, responsible for signal analysis, fault judgment and actuation execution, the central control part of the entire protection device.
• Terminal Block: Specialized terminal for connecting the secondary circuit of Current Transformers (CTs), ensuring stable and reliable signal transmission between CTs and the relay body.
• Output Terminals: Equipped with relay actuation signal terminals (normally open/normally closed contacts) for linking with circuit breakers and other control equipment; also integrated with fault indicator lights (red or yellow) for intuitive operation status monitoring.
• Power Input Terminal: Dedicated interface for connecting 48V or 125V DC power supply, providing stable power support for the relay’s continuous operation.

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5. Application Fields

• Transformer Differential Protection: Serves as the primary protection equipment for power transformers in power systems, dedicated to detecting and responding to various internal transformer faults.
• Power Distribution Systems: Deployed in distribution networks and substations to provide comprehensive protection for large and medium-sized transformers, safeguarding the stability of regional power supply.
• Power Grid Automation: Collaborates with other relay protection devices, monitoring equipment and control systems to form a complete and coordinated power grid protection and automation system, enhancing the overall safety and intelligence of the power grid.