Current inrush limiting apparatus
AssigneeTRW Inc.
InventorFenwick R. McLeod, Jr.
Life of this patent
Estimating the term…
Abstract
Current inrush limiting apparatus is disclosed including a power supply circuit (32) which regulates the transmission of power from a source (12) to a load (14). A soft start control (36) controls the power supply to prevent excessive current inrush to the load by causing it to apply power to the load gradually when the power first comes on. A dropout timer (38) monitors the power signal and rapidly resets the soft start control circuit if a power dropout exceeds a predetermined minimum duration. This ensures that excessive current inrush also does not occur following brief power dropouts.
Claims8
Apparatus for transmitting power from a power source to a load, comprising:
- first means for controlling the level of power transmitted to said load from said power source, including means for soft starting the transmission of power to said load, upon initial turn-on of said power source, by initially transmitting power at a low level and thereafter gradually increasing the level of transmitted power to a higher level said soft starting means being responsive to a reset signal to completely reset the soft start function;
- and
- second means for providing said reset signal to said soft starting means only if the power provided by said power source drops out for in excess of a predetermined interval of time whereby when power thereafter returns the transmission of power to said load is again soft started at said low level.
Apparatus for controlling the application of an A.C. power signal to a load in such a manner as to prevent excessive current inrush, comprising:
- A.C. phase control power supply means responsive to a control signal for varying the phase angle at which said A.C. power signal is applied to said load, said power supply means responding to a control signal having a first value to apply power at a phase angle wherein said A.C. power is applied to said load at a first level and to a control signal having a second value to apply power at a phase angle wherein A.C. power is applied to said load at a second level greater than said first level;
- means for providing said control signal to said power supply means, said means providing said control signal having said first value upon the initial application of power to said apparatus, and thereafter gradually varying said control signal value towards said second value, said means being responsive to said reset signal for resetting said control signal to said first value within a fraction of a cycle of said A.C. power signal;
- and
- reset means responsive to the withdrawal of said A.C. power signal from said apparatus for providing said reset signal to said control signal providing means only upon the withdrawal of power for in excess of a first predetermined period of time,
- whereby power withdrawals which are shorter than said predetermined period of time do not reset said control signal providing means but power withdrawals in excess of said predetermined period of time cause said control signal providing means to reset said control signal within a fraction of a cycle of said A.C. power signal.
Dependencies are inferred from the claim text.