OVERVOLTAGE LEVEL
The output voltage level at which the overvoltage protection latch is activated may be adjusted locally via a 10-turn potentiometer accessed through the top cover.HSP power supplies incorporate output overvoltage protection (OVP) circuitry which latches the output regulator off in the event that the output voltage rises above a predetermined level. Reset requires that the user remove source power for a minimum of 30 seconds (optional remote reset. The trip level is preset at the factory for 130% of the nominal output voltage , however, this level can be adjusted from 100% to 140% of the nominal output (except Model HSP 48-21, which can be adjusted from 100% to 160% of the nominal output) via the OVP ADJUST control accessed through the top cover.
The signal generated by the OVP detector is gated with a signal from the fault detector circuit to produce a selective overvoltage shutdown function which prevents shutdown of operational power supplies in a parallel-redundant power system configuration. The OVP latches of any working power supplies are disabled, allowing only the faulty modules to be latched off; system operation can then return to normal, assuming sufficient load capacity in the remaining modules to support the load. This function is critical in fault-tolerant power systems, otherwise a single overvoltage failure could ripple through all of the operating supplies and result in a complete power system loss.
NOTE: The overvoltage protection circuit senses the voltage directly at the output terminals of the power supply, not at the error sensing point. When selecting an overvoltage set point, the user must take into account the expected power lead voltage drop and, if applicable, the transient response overshoot in order to avoid false shutdowns. The HSP design is such that the power supply cannot generate an output voltage high enough to cause internal damage, regardless of OVP setting.
