The power supply supplies power to the modules on the backplane. Generally power from field devices DOES NOT come from the power supply. The power supply only provides control power to modules on the backplane. Power for field devices come from a separate source which is connected to the output module. The power supply merely provides the power needed to shut a contact, or fire a triac or transistor to pass power from this external source to the field device. On the back of the power supply, a jumper is used to set the voltage range for AC Power Supplies.
The current ranges for each voltage tap are listed inside the power supply door. Each module’s label will declare how much current it requires from the power supply. Add all the current rating requirements together for each voltage tap, and make sure they do not exceed the limitation of the power supply.
If an AC supplied power supply becomes overloaded, it will shut down. If this happens, you can reset the power supply, by cycling power for 45 seconds after correcting the overload condition.
24v power supplies are also available, depending on your voltage requirements.
If you determine that a power supply needs to be replaced, simply remove power, and disconnect the power supply leads. You will find two screws inside the power supply door on the right side of the module. When you loosen these two screws, the power supply will pull directly forward for removal from the chassis. Be sure to check the High/Low jumper on the new power supply if applicable, then insert the new power supply, tighten the holding screws, and re-connect the leads to the new module.