6mA DC sensitive residual current monitoring for AC charge stations
Published: 11 December 2018 - Sarah Mead
RCMB121- compliant and safe charging at a lower cost.
As of January 1st, 2019, it is stated in IET Wiring Regulations 18th Edition Section 722.531.2.101 that it will be a requirement for protective measures against DC fault current to be designed into all electric charge stations.
In electric vehicle charging if the DC fault current is greater than 6mA, it could change the characteristics of a Type A RCD due to its core saturation, resulting in the type A failing to trip and a lack of detection of the DC fault. In this instance, the risk of electric shock is increased, and safety is compromised.
The new wiring regulations BS7671:2018, 18th Edition Section 722.531.2.101 approves two provisions of DC fault protection:
Use type B RCD, which is suitable for AC and DC fault protection but usually the costs are 10 times the cost of type A RCD.
Use type A RCD and a DC 6mA sensor to provide a means of disconnection of supply in case of DC fault, which is commercially a much more attractive solution.
Bender UK has launched a new 6mA DC sensor RCMB121 that is designed to detect a DC earth fault, which is more cost-effective than using a Type B RCD. This sensor activates automatic shut-down through an external disconnection device in the event of hazardous electrical faults occurring.
The RCMB121 works in conjunction with a Type A RCD to provide a significantly cheaper alternative to type B RCD for AC charge stations. It enables compliance with the BS7671:2018, providing maximum safety at a considerably lower cost than using a Type B residual current circuit breaker.
This new 6mA DC sensor enables compliance with the updated BS7671:2018 and reduces the cost of developing electric vehicle charging solutions. For more information visit our product page.