DC power for controls

[JdoubleU]

I was trouble shooting a pump alarm and found that the controls for these Vault pump alarms use DC voltage. They use 120v for the controls to the alarms. They use a converter to convert 120AC to 120DC voltage for the controls. What is the reason for this.

 

[Buck Parrish]

Probably designed for a battery back up system to easily adapt.

 

[beanland]

125vdc

125vdc

Spot on. Utilities often use 125VDC for control because this is a typical battery voltage they use. In this fashion, control can be maintained even during a POCO outage.