Type B Earth Leakage Relay - A Comprehensive Guide

Type B Earth Leakage Relay – A Comprehensive Guide

Type B earth leakage relay is a Type B leakage protection class, which can detect all types of leakage current, including AC, pulsating DC, smooth DC fault current, and high frequency leakage current. It is usually used in conjunction with leakage current transformers. When the leakage current exceeds the set value, it will send a signal to the shunt coil of the circuit breaker (MCB/MCCB or ACB) to trigger alarm and pre-alarm.

Blue Jay Type B Earth Leakage Relay

Detects AC, pulsating DC and smooth DC fault currents

Enhance safety for advanced power electronics, EV charging stations, and renewable energy applications.

Why do you need a Type B earth leakage relay?

First, the Type B earth leakage protection relay is the most comprehensive protection measure to protect personnel and loads from leakage of alternating current (AC), direct current (DC), or mixed current (AC/DC). Secondly, local regulations or IEC standards require leakage current protection for loads/equipment. Finally, the existing Type A and Type AC earth leakage relays cannot effectively detect large smooth DC leakage currents, thus losing the ability to detect AC leakage currents, but this is not the case with the Type B earth leakage relay.

What applications can the type B earth leakage relay be used for?

Type B earth leakage relays are mainly used in the following fields: electric vehicle charging piles (especially DC charging piles), photovoltaic inverters, inverter drive systems (such as HVAC, pumps, fans, elevators, cranes, etc.), UPS uninterruptible power supplies (data centers, server rooms), medical equipment power supply (operating rooms, ICU, etc.), industrial control equipment, etc.

Application	Core Leakage Current Risk	Function of Type B Earth Leakage Relay	Type B RCD/RCBO Tripping Current (IΔn)	Additional Requirements
Electric Vehicle Charging Pile	Charging pile internal AC/DC module malfunction, generating smooth DC leakage current.	Detects DC leakage current from charging pile internal circuits/components. Prevents electric shock risk to users and fire hazard from irregular current.	30mA	4-pole, 10kA Breaking Capacity
PV Inverter (Photovoltaic Inverter)	Inverter malfunction causes DC backfeed, forming a DC leakage current.	Detects DC leakage current from the inverter. Prevents DC current flowing into the human body and damage to the inverter/transformer.	300mA	Lightning Protection Coordination
Variable Frequency Drive (VFD) System	High-frequency AC current (1kHz~20kHz) and pulsating/smooth DC components caused by frequency conversion.	Detects high-frequency AC leakage current from motor insulation damage and continuous DC current from external factors. Prevents A-type RCD malfunction or non-tripping due to DC leakage.	100mA (Time-delayed)	IP54 Protection
UPS Power Supply	Two-way conversion causes high-frequency DC and AC components in the UPS output.	Protects UPS input/output circuits from high-frequency DC and AC components. Prevents cascading accidents in data centers caused by UPS fires.	100mA	Dual-path Redundancy
Medical Equipment	Micro DC leakage current	Achieves dual-layer protection with isolation transformers.	30mA	Medical IT System Certification
Industrial Control Equipment	Prevents equipment malfunction due to DC leakage current, reducing production downtime (avoids A-type RCD mis-tripping).	Protects precision control devices from electromagnetic interference (EMI).	30mA/300mA (adjustable)	EMC (Electromagnetic Compatibility) Anti-interference Design

What is the difference between Type A and Type B earth leakage relay?

Types	Type A Earth Leakage Relay	Type B Earth Leakage Relay
Leakage Current Detection	AC and pulsating DC current leakage	AC, pulsating DC and smooth DC current leakage
Application	Suitable for residential, commercial and light industrial applications	Phase variable speed drives (VSD) and inverters Electric vehicle (EV) charging stations Photovoltaic (PV) solar inverters and industrial equipment
Response sensitivity	DC component > 6mA may refuse to operate	smooth DC ≥ 6mA can operate reliably

How to choose type A and type B earth leakage relay?

The core of choosing between Type A or Type B ELR is based on risk assessment and load characteristics. For standard AC loads and simple electrical installations, Type A ELRs provide adequate protection. However, with the advancement of technology and the widespread application of complex power electronic equipment in residential, commercial, and industrial fields, Type B earth leakage relays have become the inevitable choice for ensuring comprehensive electrical safety and meeting modern leakage current challenges. Especially in medical environments, advanced industrial systems, renewable energy, and electric vehicle charging stations, where life safety is critical, Type B ELRs are not only in compliance with regulatory requirements but also provide the ultimate protection for life and property.

What reliable brands are there for Type B earth leakage relay?

Blue Jay‘s strengths in the field of Type B leakage current protection relay are its in-depth expertise, comprehensive detection capabilities for all leakage current types, high accuracy, intelligent diagnosis and fault location functions, and wide recognition in medical, new energy, charging pile, and critical industrial applications in China. Additionally, it primarily focuses on offering low-cost and high-quality Type B leakage current protection relays.

Frer, an Italian company specializing in power measurement and protection, provides a series of high-performance Type B earth leakage relays, usually split ELRs, which need to be used with external residual current transformers (CTs). Its Type B ELRs are known for their high measurement accuracy and sensitive action.

Circutor, a Spanish company, usually incorporates advanced measurement and monitoring technologies into its Type B leakage current protection relays. Circutor’s Type B earth leakage protection relays are suitable for electric vehicle charging piles, photovoltaic systems, inverters, UPS and other equipment that generate DC or high-frequency leakage currents

LOVATO Electric is an Italian manufacturer of low-voltage electrical equipment that provides a comprehensive Type B leakage protection solution, including integrated RCBOs and split ELRs. It offers a variety of B-type products with rated current and leakage sensitivity to meet the needs of different industrial applications.

Schneider offers a very comprehensive and technologically advanced B-type leakage protection relay, covering integrated and split solutions. Its B-type leakage current protection relay can be seamlessly integrated into Schneider’s various energy management and automation platforms.

Contrel focuses on electrical measurement and control, and its type B leakage protection relay products generally have high-precision and professional functions. It provides B-type ELRs with high-resolution measurement and precise fault diagnosis capabilities, offering a range of models to meet various application needs.

FANOX focuses on protection relays, and its Type B earth leakage relay also reflects its expertise in the field of protection and control. It provides B-type leakage current relays designed specifically for industrial applications, emphasizing reliability in harsh industrial environments. Its B-type leakage current relays are suitable for industrial loads such as pumps, fans, motor drives (inverters), industrial machinery, etc., that have strict requirements for leakage protection.