12vAdapters.com

When choosing a power supply for a DC motor, you must know two things about a motor. These are the continous draw of the motor, measured in AMPS, or Watts, and the Peak Draw. The continous draw is the amount of power, or load, that the DC motor pulls from the power supply when it is already running. This is usually a smaller number than the peak draw. It is often measured in Watts, which is equal to the Amperage of the motor, multiplied by the voltage. So a 5 Amp DC motor running at 12V will consume 60 Watts of power. This is called the continuos draw, and must be less than the contimous load rating of the power supply. THe other major factor to consider when selecting a power supply for a DC motor is the peak draw. This is the amount of draw when the motor is just starting up, going from a stopped to running state. This peak power limit is usually significantly higher that the continous draw... So if a motor draws 3A on continous running, it might draw up to 5 Amps or more for a few moments as it starts running. Most switching power supplies have a protection circuit, which will turn them off if load peaks beyond it's safe capabilities. You must ensure that the peak rating of the motor does not surpass the peak shutoff protection of the powr supply. An example is, that if you want to power a DC motor with a 3A continous draw, you must assume the peak draw as about 50% more, so you should select a 5A power supply. This will be enough to get through the peak power usage, and will of course have no trouble running the continous load of 3A. Hope that makes it clear.....