3VA Large Frame DAS Installation

The new 3VA large frame circuit breakers (1200A, 1600A, and 2000A frame sizes) now have Maintenance Mode, or DAS, integral to the trip unit with terminals inside the cover to wire an external switch, light, and 24V power supply. Previously with 3VA, specifically frames smaller than 1200A, it was required to have an MMB300 to wire these external components to the breaker. However, since the NEC requires Maintenance Mode on breakers 1200A or larger, the feature was integrated into the breaker to reduce parts and create an easier solution for customers looking to satisfy the NEC 240.87 requirement for Maintenance mode. It should be noted that DAS mode can be activated on trip units that have an LCD screen (5 series and 8 series trip units) without the use of external components. If DAS mode is activated through the LCD screen interface the external switch will not be able to deactivate DAS; and vice versa. 

You will find the DAS terminals inside the accessory cover of the 3VA large frame breakers on the left side. They appear to be 2 black aux contact with 3 inputs each. While they are marked in the same fashion as form C contacts, they are wired internally to the trip unit and do not function as aux contacts. These are circled in red in the attached photo.

The wiring diagram can be found in the manual and also attached to this article. The components are to be wired exactly as the position of the terminals shown. I.e. the top left position in the diagram corresponds to the top left position in the breaker terminal. 

For further questions regarding DAS please reach out to componentsae.ic@siemens.com