Transformer Load & Power Consumption Chart

Excerpt from HOW TO OPERATE YOUR LIONEL TRAINS, 1959, Page 52

How To Estimate Available Power:

The wattage rating of a transformer tells you how much power it will take from your household mains. However, all of this power is not available for your train. From about one-quarter to one-eighth of the total wattage taken from the lines is used up by the transformer itself in transforming the power from high to low voltage. This wattage loss becomes apparent in the warming up of the transformer as it is used.

A transformer operating continuously for long periods of time or in warm surroundings will be able to deliver less power than one used intermittently or in cool surroundings. As the transformer warms up in use its output voltage and wattage will drop gradually.

As an example, a 90-watt No. 1033 transformer should not be used to deliver more than 60 watts of usable low-voltage power. A 275-watt ZW transformer should not be counted on to supply more than 200 watts. It is important to take this loss into consideration when estimating the amount of equipment your transformer can operate.

Another and simpler way to determine the amount of equipment which you can add to your train layout is by considering the amount of current, in amperes, which can be supplied by your transformer continuously, without overheating. The following table lists the current which can be supplied by Lionel transformers for at least four hours of continuous operation, under normal temperature conditions.

Transformer Amperes

Transformer    Max. Output Amps
1015 2.5
1043-1053 3.0
1033-1044 4.0
LW 5.5
KW 8.0
TW 8.0
ZW 12.0


How To Estimate Your Power Requirements

While electric power is normally calculated in watts, you can obtain a very close approximation of the requirements of your model railroad by adding up the current, in amperes, consumed by your equipment, counting 1-1/4 amperes for each motor, and 1/5 amperes for each steadily burning lamp.

You do not need to figure in the power requirements of automatic couplers and operating cars, since the couplers draw current for only an instant and operating cars only when the train is not running. For the same reason, do not add power used by such accessories as coal elevators, log loaders and other operating devices which are put in action when the train is not running.

Even with a small transformer your layout can contain as many operating accessories as you wish provided that you operate them one at a time.

For example, if your outfit consists of a 5-car illuminated passenger train pulled by an "O" gauge twin-motored locomotive, and you have a pair of No. 022 switches, 4 lamp posts and a couple of block signals you could make a table, as follows:


Equipment Quantity Current   Total Amps
Motors 2 1.25 2.5
Headlights 2 0.2 0.4
Car Lights 10 (2 in each)  0.2 2.0
Switch lights 2 0.2 0.4
Switch controllers 2 0.2 0.4
Block Signal lights 2 0.2 0.4
Total current 6.1 amps


This would mean that your outfit would require a continuous current of approximately 6 amperes and would call for a KW or a TW transformer.

Again, note that installation of several operating units such as a No. 356 Station and a No. 350 Transfer Table will have practically no effect on your power requirements.