Abstract Fast-slewing regulated power supplies exhibit very short duration transient overvoltage conditions. These overvoltage spikes are attenuated when above a predetermined level. Overvoltage conditions of longer duration activate further clamping means and means for turning off the power supply. Regulated power supplies are designed to supply predetermined voltage or current to a load. Highly regulated, stable power supplies are available. During normal steady-state operation the regulated voltage or current remains constant and no problems exist. Many loads for which such power supplies are used are extremely sensitive to overvoltage conditions, even those of extremely short duration. Power supplies having large capacitors across the output terminals tend to absorb short duration overvoltage tendencies or ''''spikes.'''' For such power supplies overvoltage protective devices are designed to respond after a short delay so that, for example, turn-on transients will not trip the power supply off at once. This leaves a source of possible trouble, i.e. the turn-on transient unprovided for. In addition, fast-slewing rate power supplies have little or no capacity across their output terminals and turn-on and similar transients are greater than in conventional power supplies. Such transients may not be tolerable with some types of overvoltage sensitive loads.
In a load-protecting system for regulated power supplies, the combination of; a pair of terminals for connection to a load to be protected; first signal responsive shunting means connected to said terminals; a source of reference voltage; means for comparing a portion of the voltage between said terminals with said reference voltage for deriving a difference voltage; means for amplifying the difference voltage to provide an output control signal; means for applying the control signal to said shunting means to activate said shunting means in the presence of a difference voltage greater than a predetermined voltage; a second signal responsive shunting means connected to said terminals; and a time delay circuit means connected between said amplifier and said second shunting means for activating said second shunting means in response to a difference voltage persisting for longer than a predetermined period of time.
Claim 2
Dependent Claim
142 words
In a load-protecting system for regulated power supplies, the combination of; a pair of terminals for connection to a load to be protected; first signal responsive shunting means connected to said terminals; a source of reference voltage; means for comparing a portion of the voltage between said terminals with said reference voltage for deriving a difference voltage; means for amplifying the difference voltage to provide an output control signal; means for applying the control signal to said shunting means to activate said shunting means in the presence of a difference voltage greater than a predetermined voltage; a second signal responsive shunting means connected to said terminals; and a time delay circuit means connected between said amplifier and said second shunting means for activating said second shunting means in response to a difference voltage persisting for longer than a predetermined period of time.
Claim 3
Dependent Claim
21 words
A load-protecting system as set forth in claim 1; and including circuit breaker means coupled to said time delay circuit means.
Claim 4
Dependent Claim
28 words
A load-protecting system as set forth in claim 1; wherein said first shunting means is a bipolar transistor and said second shunting means is a silicon controlled rectifier.
Claim 5
Dependent Claim
18 words
A load-protecting system as set forth in claim 1; wherein said time delay circuit means is substantially noncumulative.
Claim 6
Dependent Claim
28 words
A load-protecting system as set forth in claim 1; and including means for varying the portion of voltage between said terminals which is compared with said reference voltage.
Claim 7
Dependent Claim
32 words
A load-protecting system as set forth in claim 1; wherein said time delay circuit means includes a capacitor, controlled rate charging means for said capacitor and fast discharge means for said capacitor.