Some transformers in the power supplies provide a little humming noise and that is normal. If the humming in Von Duprin PS873 power supply is loud follow these steps. Remove the load from the outp...
Battery backup can be added to the PS900 series power supplies. Order the 900-BBK to get the battery backup board and batteries for field installation.
Attached table provides how long the battery back up will last with a PS914 power supply.
Load (Amp
DC)
Battery
backup time
Comments
0.3 Amp
20 hours
Continuous load
...