MK Sentry RCD 100A 30MA 230V DP Type A 2 Module

Product Information

The initial verification required under 641.1 and 301.1 (ii), covers the requirements for the verification that electrical equipment (any appliance supplied or connected, as part of the existing fixtures and fittings) is compatible with other electrical equipment such as RCDs installed to provide additional protection e.g. for a domestic installation, document the appliance RCD requirements with the justification for the consumer unit specification.

Type AC RCDs subjected to pulsed waveforms will not trip within the safe limits, required for 30mA protection. Appliances containing diodes, produce pulsed residual currents – see Fig 1. Diodes became so common in domestic equipment some years ago, that many countries banned the "general use" of Type AC RCDs e.g. From 1985, VOE Regulations specified the use of Type A RCDs in all domestic installations as a minimum requirement.RCDs are far more sensitive than circuit-breakers. The sensitivity being rated in milliamps (mA) as opposed to amps (A). Different Types of RCD Type A RCDs are not designed to detect smooth dc residual currents. They will still trip within safe limits with < 6 mA smooth dc superimposed on a 50Hz pulsed residual current.

In new installations, it is common practice to install a consumer unit which was supplied with RCDs already connected. These are likely to be Type AC which could be ineffective due to the residual DC fault current created by types of electrical equipment. Many installers, either because of habit or a misunderstanding of the limitations for an AC Type RCD, often assume they are suitable for all installations, but this is incorrect.

UK electricians can still make informed technical decisions

NOTE 4: For guidance on the correct use of RCDs for household and similar use, see PD IEC/TR 62350.

Fault Protection. Any tripping current dependent on the resistance of the earth path. (Regulations 411.4.204; 411.5.1; 531.2). Type F RCDs are not designed to detect smooth dc residual currents. They will still trip within safe limits with < 10 mA smooth dc superimposed on a 50Hz pulsed residual current. In a healthy circuit, the vector sum of the currents flowing in all live conductors should be nominally zero. When a fault occurs on a circuit causing a current to flow to earth, this creates an imbalance and trips the device. What is DC residual/fault current? Type A RCDs are used for alternating sinusoidal residual current and for residual pulsating direct current up to 6 mA.Should be neutral - but I accept the motivations of the reader may focus on what is more important to them. It should be noted that the residual DC leakage current can vary with motor speed and cable length. Type B devices are also suitable for Type AC, Type A and Type F applications. How do I test the different Types of RCD? To help explain, it might be worth thinking about some older models of earth fault loop impedance testers, which could cause the RCD to operate unintentionally. To prevent this, some types of earth fault loop impedance testers imposed a DC current on the AC test current. This DC current saturated the magnetic core of the RCD preventing it from tripping under the test condition. Industrial installations using uninterruptible power supplies (UPS) and variable speed drive (VSD) frequency inverters for the speed control of motors.