Tested for Safety. We can only guarantee trouble-free operation of our trains when used with original Märklin transformers. These transformers must be protected from moisture and are not approved for outdoor use. These transformers are to be connected only to AC power. Please also read the operating instructions for these components. Multi-Train Operation with Separate Power Circuits. In conventional train operation, if several trains are to be operated independently of each other, the layout is divided into several power circuits. A transformer and at least one feeder track are assigned to each power circuit and each circuit is easily separated electrically from other power circuits with center conductor insulators (74030, 5022, or 7522). In the Märklin H0 system, running rails have the same polarity everywhere on a layout and do not need to be interrupted. Power circuits can be closed routes like most main lines or other areas of track with their own operation. Examples of the latter would be branch lines, station areas, storage sidings, switchyards, or railroad maintenance facilities. This gives you the possibility of controlling individual locomotives for specific purposes along with fully automatic route operations. As a rule, catenary for electrified routes is also connected to its own transformer as an additional power circuit for each area of catenary. This allows you to control locomotives used in catenary operation independently of locomotives or rail cars powered from the center conductor on the track. Two or more catenary power circuits can be separated from each other with the 70221 (7022 in the old catenary system) contact wire interrupter. The output power (in VA) specified on the transformer is available for the power consumption of all users in that power circuit. Some sample calculations for power consumption: Smaller locomotives with a load (example: 30001 tank locomotive or similar units) require about 9 VA, larger locomotives (example: 33803 diesel locomotive) about 12 VA. The power consumption for train lighting depends on the light bulbs being used and is usually less than 2 VA per car. After subtracting the output required by trains, the remaining reserve can be used at the accessory outputs for electric accessories. Here, light bulbs consume between 0.5 and 1 VA (see the table ”Light Bulbs for Accessories”) and turnout or signal mechanisms require about 6 VA at the moment they are activated. Additional electric accessories should be connected to additional accessory transformers. The 66471 safety transformer is not a toy for children.