Earth Leakage CT for ELR-4MA AC Earth Leakage Relay
BLUEJAY’s ELR-4MA AC Earth Leakage Relay is a high-performance protection device designed to monitor residual currents and enhance electrical safety in industrial and commercial systems. Using a residual current transformer (RCT), it detects leakage currents and triggers alarms when thresholds are exceeded, preventing electrical hazards.
Type AC, A, F and B Residual Current Transformers
RCTs detect leakage currents in electrical systems, each type suited for different applications:
Type AC RCT
Function: monitors the residual sinusoidal AC current that is suddenly applied or slowly rising. Suitable for linear loads, sensitive only to sinusoidal AC.
Applicable scenarios: Single-phase AC loads without rectifiers in industrial and commercial buildings.
Typical equipment: Electric heaters, industrial ovens, high-power vacuum cleaners, resistive load equipment.
Type A RCT
Function: Monitors the pulsating DC residual current and the pulsating DC residual current superimposed with 6mA smooth residual current, which contains the characteristics of the AC type. Applicable to equipment with rectifier loads, it can detect sinusoidal AC and pulsating DC components.
Applicable scenarios: Equipment containing electronic rectifier components in commercial buildings and office spaces.
Typical equipment: Electromagnetic heating equipment, industrial microwave ovens, smart dishwashers, computers and office equipment in office buildings.
Type F RCT
Function: In addition to the faults covered by Types A and AC, Type F RCT covers the residual current with multiple frequencies up to 1000Hz. However, the residual fault current should limit the pure dc component to 10mA or lesser. Their representation includes a sine wave, a pulsating dc, and a high-frequency sine wave.
Applications scenarios: designed for single-phase variable frequency loads, which involve AC/DC conversion and high-frequency switching components.
Typical equipment: Industrial HVAC systems, frequency-controlled water pumps, heat pumps, and other single-phase variable frequency-driven equipment.
Type B RCT
Function: Contains the protection characteristics of Type A, and in addition, it can monitor the sinusoidal AC residual current of 1000Hz and below, AC residual current superimposed with smooth DC residual current, pulsating DC residual current superimposed with smooth residual current, pulsating DC residual current generated by two-phase or multi-phase rectifier circuits, and smooth DC residual current.
Applicable scenarios: industrial automation, transportation and new energy applications, equipment involving variable frequency drive and AC/DC conversion.
Typical equipment: cranes, cranes, elevators, industrial frequency conversion equipment, three-phase photovoltaic inverters, electric vehicle charging piles, medical and mining isolated power supply monitoring systems.
BLUEJAY’s Capabilities
The ELR-4MA currently supports AC and A-type detection, ensuring precise leakage monitoring for industrial and commercial environments. This enhances safety, minimizes downtime, and protects equipment. For B and F-type applications, BLUEJAY continues to innovate to meet evolving industry needs.
By understanding the differences between AC, A, B, and F-type RCTs, users can select the appropriate protection device, ensuring reliability and compliance in modern electrical system.
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