ESS30-S003-DC24V-2A E-T-A Circuit Protection and Control. Circuit Breakers UL1077, 1P, plug, 24VDC, Aux Cont, 2A. The electronic circuit protector ESS30-S with physical isolation is the globally unique electronic overcurrent protection for DC 24V applications as a “low energy breaker”. It meets the requirements to DIN EN 60934 and UL 1077 as a supplementary protector in central and decentralized energy supply units. The compact device can be plugged into the terminal block systems 17PLUS and 18PLUS and is also suitable for the SVS power distribution systems, ensuring quick and easy installation. DC 24V switch-mode power supplies are widely used in automation today. In the event of an overload, however, they turn down the output voltage which is intended to power all connected loads. So if there is a failure in a single load of the system, the supply voltage will break down also in all other load circuits. Not only does this frequently cause undefined fault conditions, but it can even lead to machine stoppages or system downtimes.