When the output power or current reaches the range of O.L.P. /O.C.P. (typically 105%~150% of rated power/current), the S.P.S. would be protected by decreasing or cutoff of output power. The protection modes for over current/overload are categorized into the following types:
(1) Foldback Current Limiting
Output current is folded back to 20% or less of rated load current (curve (a) in figure 2.9).
(2) Constant Current Limiting
Output current remains constant and within the specified range while the output voltage drops to a low level (curve (b) in figure 2.9).
(3) Over Power Limiting
Output power remains constant. As output load increases, output voltage decreases in proportion (curve (c) in figure 2.9).
(4) Hiccup Current Limiting
Output voltage and current keep pulsing ON and OFF repeatedly when protection is activated. The unit automatically recovers when fault condition is cleared.
(5) Shut Off
Output voltage and current are cut off when output load reaches protection range.
(1) Auto Recovery: S.P.S. recovers automatically when over current/overload condition is removed or over.
(2) Re-power on: S.P.S. restarts by manual AC re-power on after over current/overload condition is removed or over.
Cautions: Please prevent from long-term overload or short-circuit, or it could lead to decreased lifetime or damage of S.P.S. Some models are designed with two-stage protection for overload or short-circuit. When in the protection mode, S.P.S. is either foldback current limited or over power limited, and then goes into shutdown or hiccup current mode after a predetermined period of time.