TYPES OF RESIDUAL CURRENT PROTECTION

Choose the most suitable protection based on the type of loads in your installation

The appropriate selection of residual current protection elements contributes to operational efficiency, allowing a fast response time to failures and reducing downtime. Residual current protection is not only a vital component for safety, but also for the efficiency and reliability of electrical installations.

Type A residual current protection
Effective and reliable protection for electrical installations, guaranteeing people's safety and service continuity.

Type A residual current protection detects AC residual currents, pulsating residual currents, and pulsating DC residual currents superimposed on a smooth DC residual current of up to 6 mA. It is the most widely used in industrial settings for protecting loads such as lighting, power outlets, single-phase drives and computer equipment

Learn more about Type A protection
Type B residual current protection
Advanced protection that detects AC, pulsating and DC earth leakage currents for loads with AC/DC conversion.

Type B residual current protection is capable of detecting DC leak currents, as well as AC and pulsating currents. It is essential for applications that can generate DC leakage currents due to the use of power electronics, such as three-phase variable speed drives, frequency converters, UPS systems, inverters, active filters or EV charging points.

Learn more about Type B protection
EARTHING SYSTEMS

Protection type by earthing system

Our range of residual current protection devices covers both earth fault tripping (TT systems and, in some cases, TN systems) and preventive insulation monitoring for critical loads (TN/IT systems). The diagram below shows a summary of their use cases according to the earthing system.

TT systems
TN systems
IT systems
Residual current protection
Mandatory
Recommended
Not necessary
Monitorización
Recommended
Recommended
Mandatory
TT system

The TT earthing system is an arrangement in which the exposed-conductive-parts of the installation are connected to a local earth electrode that is independent of the supply earth. Protection of persons is provided by residual current devices (RCDs), which automatically disconnect the supply in the event of an earth fault.

Residual current protection

It provides protection against both direct and indirect contact and ensures effective protection of the installation against earth faults, since automatic disconnection of the supply depends directly on the operation of the RCD.

Earth leakage monitoring

Enables the trend in earth leakage current to be monitored and provides the data needed to correctly set the sensitivity and time delay of the protection, preventing nuisance tripping and detecting faults before they result in unplanned downtime.

TN-S system

The TN-S earthing system is an arrangement in which the exposed-conductive-parts of the installation are connected to the supply protective conductor. Safety is provided by overcurrent protective devices and, depending on the application, residual current protection, which disconnect the supply in the event of an earth fault.

To ensure protection

In high-impedance systems, such as installations with long cable runs, residual current protection is essential to ensure correct operation of the protection system, since overcurrent protection may not always provide effective fault clearance.

To protect loads

Residual current protection prevents damage to connected equipment caused by high fault currents, which can seriously damage both electrical equipment and cable insulation. By operating at lower fault currents, it enables rapid and effective disconnection, protecting connected equipment as soon as a fault is detected.

Earth leakage monitoring

Allows insulation deterioration in connected equipment to be detected before an insulation fault occurs, helping to prevent service interruptions and reduce operating costs.

IT system

The IT earthing system is an arrangement in which the live conductors are either insulated from earth or connected to earth through a high impedance. This system maintains continuity of supply following the first earth fault, which is detected by an insulation monitoring device, ensuring a high level of safety and system availability.

Residual current protection

Not required because the neutral is isolated from earth and the current generated by a first earth fault is very low, so continuity of supply is not affected. A second fault would actuate the overcurrent protection.

Earth leakage monitoring

Detects earth leakage before a second fault causes the overcurrent protection to trip. The RCD provides an early warning of a first fault, allowing appropriate maintenance to be carried out and helping to avoid downtime in critical systems.

Discover the difference between Type A and Type B protection

Learn how to identify the most suitable residual current protection for your installation and the connected loads. Choosing the right protection is essential to ensure both electrical safety and continuity of service.

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SERVICE CONTINUITY

Type A residual current protection

Type A residual current protection is a key element in ensuring electrical safety in installations. It is designed to detect earth leakage currents in both alternating current and pulsating DC currents generated by electronic loads commonly found in industrial, commercial and service-sector installations.

Circutor’s solutions provide effective protection, safeguarding both people and the installation itself against earth leakage currents and insulation faults. Thanks to their high reliability and super-immunized design, Type A RCDs maintain continuity of supply in the presence of non-hazardous leakage currents and leakage currents with high harmonic content, while also preventing nuisance trips caused by transient effects, minimizing electrical risk without compromising continuity of service.

Type A residual current protection

The correct installation of residual current protection devices ensures both personal safety and continuity of service in electrical installations.

Residual current protection with reclosing system

Electrical installations where uninterrupted continuity of supply is essential in the event of unexpected situations.

Earth leakage protection for electric vehicles

As the number of charging points increases, so does public exposure, making suitable residual current protection essential.

TYPE A PROTECTION

Why install ultraimmunized Type A residual current protection?

Although Type A protection is the most common type used in industrial and commercial installations, it is important to distinguish between devices with and without a ultra-immunized design in order to avoid unwanted trips. Selecting a ultra-immunized RCD can prevent unnecessary service interruptions that should not occur under normal operating conditions.

Trip margin set to 85% of the leakage value

Standard RCDs may trip at as little as 50% of their rated residual operating current. The ultra-immunized system ensures tripping at 85% of the configured sensitivity threshold.

Harmonic filtering (high-frequency leaks)

The ultra-immunized system monitors 50/60 Hz earth leakage currents while filtering out high-frequency components to prevent tripping caused by harmonic leakage currents.

Immunity against transients in the grid

Avoids unexpected trips in the event of weather or transitory phenomena caused by the distribution grid.

SERVICE CONTINUITY

Type A residual current protection

We offer a comprehensive range of Type A residual current protection solutions, tailored to the requirements of every switchboard and installation. Our portfolio includes compact devices with a choice of sensitivities and time delays—fixed or adjustable—as well as models with communications, remote control and on-screen monitoring, and control units capable of operating up to four independent circuits, all while minimizing space requirements within the electrical panel.

Type A Protection and Monitoring (MRCD – Modular Residual Current Device)

Residual current protection devices for tripping and/or monitoring earth leakage currents in:

TT system
TN-S system
—

RGU-10A

Type A ultra-immunized residual current protection and monitoring relay

More info on the RGU-10A

—

CBS-40A

Type A residual current protection and monitoring relays with 4 channels

More info on the CBS-40A

—

WGC

Earth leakage transformers
for Type A relays

More info on the WGC

Type A Solutions for Residual Current Monitoring (RCM)

Residual current monitoring devices for tripping and/or monitoring earth leakage currents in:

TN-S / TN-C systems
IT systems
—

RGU-100A

Ultra-immunized Type A residual current monitoring relay

More info on the RGU-100A

—

CBS-400A

Type A residual current monitoring relays with 4 channels

More info on the CBS-400A

—

WGC

Earth leakage transformers
for Type A relays

More info on the WGC

TYPE A PROTECTION

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Type B residual current protection

Type B residual current protection is a key element in ensuring electrical safety in installations with loads that may produce DC leakage currents. It is designed to protect both people and equipment in circuits where there is a risk of earth leakage involving direct current (DC), alternating current (AC), pulsating AC, or mixed leakage currents comprising both AC and DC components. These types of leakage currents are common in electronic loads used throughout industrial, commercial and service-sector installations.

Type B residual current protection is used as a universal solution for protecting loads such as variable speed or frequency drives, inverters, cold storage systems, HVAC systems, UPSs and electric vehicle charging equipment.

Type B residual current protection

The correct installation of residual current protection devices ensures both personal safety and continuity of service in electrical installations.

Residual current protection with reclosing system

Electrical installations where uninterrupted continuity of supply is essential in the event of unexpected situations.

Earth leakage protection for electric vehicles

As the number of charging points increases, so does public exposure, making suitable residual current protection essential.

TYPE B PROTECTION

When is type B residual current protection recommended?

Loads incorporating AC/DC conversion can generate both AC and DC leakage currents, affecting the safety of both the installation and personnel. For this reason, manufacturers of equipment using this technology specify in their technical manuals that Type B residual current protection is required.

Three-phase variable speed drives

Solar inverters

UPS

Power electronics

HVAC systems

Electric Vehicle

SERVICE CONTINUITY

Type B residual current protection

Find the ideal Type B protection device to protect your loads or electrical panels. The range includes multiple sensitivity and time-delay settings, as well as versions with integrated communications, remote control and display-based monitoring. To save space in the panel, our multichannel units can be used for both residual current protection and residual current monitoring.

Type B Protection and Monitoring (MRCD – Modular Residual Current Device)

Residual current protection devices for tripping and/or monitoring earth leakage currents in:

TN-S system
IT system
—

RGU-10B

Type B earth leakage protection and monitoring relay

More info on the RGU-10B

—

CBS-400B

Type B monitoring and protection relay with 4 channels

More info on the CBS-400B

—

WGB

Earth leakage transformers
for Type B relays

More info on the WGB

Type B Solutions for Residual Current Monitoring (RCM)

Residual current protection devices for monitoring leakage currents in:

TT system
TN-S / TN-C systems
—

RGU-100B

Type B residual current monitoring relay

More info on the RGU-100B

—

CBS-400B

Type B residual current monitoring relay with 4 channels

More info on the CBS-400B

—

CBS-2000AB

Type A and type B multichannel leakage current monitoring relay

More info on the CBS-2000AB

TYPE B PROTECTION

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