Programming Output ProtectionSet the Over-Voltage ProtectionSet the Over-Current ProtectionOutput Watchdog TimerUser-Defined ProtectionClear Output Protection FunctionsProtection Shutdown BehaviorIntroductionThe APS models have many protection functions. These functions disable the output to protect thedevice under test as well as the power supply. A front panel status indicator will turn on when aprotection function has been set. Most protection functions are latching, which means that they mustbe cleared once they have been set. Of the following protection functions, the OV, OC, PROT, INH, andUProt are user-programmable.OV Over-voltage protection is a hardware OVP whose trip level is a user-programmable value. Over-voltage protection also occursautomatically if the remote sense leads are shorted. OV protection is always enabled.OV- Negative over-voltage protection detects if the remote sense leads are reversed. At instrument turn-on, it also detects if voltagesmore negative than -2V are present at the output terminals. OV- protection is not programmable and is always enabled.OC Over-current protection is a user-programmable function that can be enabled or disabled. When enabled, the output will be dis-abled when the output reaches the current limit setting.CP+ Positive over-power compares the output power against a built-in threshold. A CP+ protection occurs when the threshold isexceeded. CP+ protection is always enabled.CP- Negative over-power compares the internally dissipated power against a built-in threshold. A CP- protection occurs when thethreshold is exceeded. CP- protection is always enabled.OT Over-temperature protection monitors the internal temperature of the power supply and disables the output if the temperatureexceeds the pre-defined limit (see OUTPut:PROTection:TEMPerature:MARGin?). Note that sensor information from anyconnected power dissipator is combined with the information from the power supply into a single indicator. OT protection isalways enabled.PF Power-fail indicates that a power fail condition on the AC mains has occurred and has disabled the output. PF protection isalways enabled.EDP Excessive dynamic protection disables the output in the event of excessive large repetitive voltage swings caused by pro-grammed voltage changes, lists, Arbs, or load-induced voltage swings (see Output Dynamic Response). If unchecked,these voltage swings could result in premature failure of components in the instrument. EDP protection is always enabled.Prot Prot indicates the output is disabled because the programmed output watchdog timer expired.INH The Inhibit input (pin 3) on the rear panel digital connector can be programmed to act as an external shutdown signal. Refer toInhibit Input for further information.UProt A User-defined protection condition has disabled the output.4 Using the Advanced Power System112 Keysight N6900/N7900 Series Operating and Service Guide
