RCM is playing an increasingly important role with high availability power supplies, which are now found in almost all market segments. Constant processes and especially sensitive applications such as computer centres, hospitals and semiconductor factories are depending on RCM in particular. Furthermore, RCM measurement offers a good alternative in all areas in which it is not possible to utilise insulation resistance measurements and residual current devices due to local or operational circumstances. The „foresighted“ monitoring described also helps to reduce alarms, as required for example with alarm management according to EEMUA 191 or NAMUR NA 102.
However, RCM can do even more – namely reduce the risk of fire! Residual current, triggered by defective insulation, can be treacherous. The current level is determined by the power of the supply network, the insulation fault resistance and the resistance to ground. With a sufficiently high current flow (with a dead earth short or corresponding low-resistance short) the upstream protective device disconnects the electrical consumers from the mains. However, if the residual current is too low then the protective device will not trigger. If the recorded fault power exceeds a value of approx. 60 Watt (approx. 261 mA at 230 V), a risk of fire exists. Residual current monitoring therefore also serves as fire prevention.