Selection Of Types Of RCD
Residual current devices (RCDs) prevent you from receiving fatal electric shocks. RCD protection is life-saving and protects against fires. If you touch a bare wire or other live components of a consumer unit, it will keep the end user from being harmed. If an installer cuts through a cable, residual current devices will switch off the power flowing to the earth.
RCD's exist in various different forms and react differently depending on the presence of DC components or different frequencies. The level of safety they provide for live currents is greater than an ordinary fuse or circuit breaker. The following RCD's are available with the respective symbols and the designer or installer is required to select the appropriate device for the specific application.
RCD Testing
When should Type AC RCD be used?
General purpose use, RCD can detect & respond to AC sinusoidal wave only.
When should type A RCD be used?
Equipment incorporating electronic components RCD can detect & respond as for type AC, PLUS pulsating DC components.
When should type F RCD be used?
Equipment with frequency controlled speed drives RCD can detect & respons as for type A, PLUS high frequency residual current.
When should type B RCD be used?
Electric vehicle chargers, PV supplies.
RCD can detect & respond for type F, PLUS smooth DC residual current.
RCD's & Their Loads
|
RCD |
Types of Load |
|
Type AC |
Resistive, capacitive, inductive loads |
|
Type A |
Single phase with electronic components |
|
Type F |
Frequency controlled equipment |
|
Type B |
Three phase electronic equipment |
More from the 18th Edition
Surge Protection
A transient overvoltage or surge is a short duration increase in voltage measured between two or more conductors. In short this means anything from microseconds (millionths of a second) to a few milliseconds (thousandths of a second) in duration.
Arc Fault Detection Devices
Arc fault protection devices (AFDD) use microprocessors to identify characteristic current flow and voltage curves that indicate an arc fault and automatically trip the affected circuit.
Overload Protection
Devices such as switches, RCCBs etc. in distribution boards and consumer units may have historically had their rated current determined after having taken diversity into account but without having considered overload protection of the devices.
BEAMA Guides
A collection of the latest guides relating to 18th Edition, Hager is proud to be a technical contributor to these guides which provide technical advice on a range of 18th Edition related topics.
