When connecting PSU power supplies in series, 
up to 2 units can be used in series and all units 
must be of the same model. When operated in 
series, the power supplies can be used to 
increase the voltage output or setup the power 
supplies to output both positive and negative 
polarities. Unlike with the parallel operation, 
the series operation does not require any 
special configuration as each power supply is 
operated and controlled individually. 
When the units are used in series, a number of 
precautions and limitations apply. Please read 
this overview before operating the power 
supplies in series.