Some users find that the Follow sockets are no longer switched off even though the main unit is switched off. This can be caused by very high inrush currents of the connected Follow units, which greatly exceed the max. load capacity of the relay and thereby weld the switching contacts.
In many cases, the switching contacts can be detached from each other again by vibrations (knocking) and thus temporarily brought back into function. However, without a change in the configuration of the Follow units, the problem usually reappears quickly.
Background:
Our automatic extension leads, as a whole and the relays used in them, are designed for a continuous load with currents of 16A. End devices with a protective contact plug are not allowed to draw more current. However, some terminal devices exceed this limit many times over at the moment they are switched on. The current consumption can rise to 50A or more for a fraction of a second. These high currents can cause welding of the switching contacts in the relay - the relay then no longer switches off.
Experience has shown that this problem occurs more frequently in terminals with switching power supplies. These can be installed almost everywhere nowadays, e.g. PC, monitor, printer, external hard drives, active loudspeakers, etc. Which products actually cause such problems also depends on whether the manufacturers of the end devices have taken appropriate measures against excessive inrush currents or not. Unfortunately, this cannot be read from any data sheet or type plate. We have optimised our automatic extension leads in this respect by using special relays for pulse loads of up to 80A. As a result, the problem occurs much less frequently.