The DP800 series power supply will show a transient voltage on the outputs when the power supply is powered up. Typically the transient voltage will show approximately 400mV p-p over a 200us duration.
The DP800 power supplies do not have output relays to to enable output after the power supply has been turned on and has stabilized. It is recommended that connections be made to a device after the power supply has been powered up if you are working with circuitry that is sensitive to this transient voltage.