Relocatable power tap with surge protector
A relocatable power tap that includes a surge protector. The surge protector provides three modes of transient voltage surge protection while limiting leakage current caused by the relocatable power tap to less than a current limit value (e.g., 100 micro-amperes [“μA”]). The surge protector includes a first transient voltage clamp connected between a line conductor and a neutral conductor, a second transient voltage clamp connected between the line conductor and a ground conductor, and a third transient voltage clamp connected between the neutral conductor and the ground conductor. The transient voltage clamps are, for example, varistors having non-linear current-voltage characteristics. In the presence of voltages that exceed the clamping threshold voltages of the transient voltage clamps, the transient voltage clamps are configured to conduct the current associated with the transient voltage.
1. A relocatable power tap comprising:
at least one receptacle;
a power supply configured to convert an AC signal to a DC signal;
a fault detector configured to determine the existence of ground and polarity faults in a power source, the fault detector including a first current-controlled switch configured to turn on if an open, ground, or polarity fault exists;
a power switch controlled by the fault detector, connected to the power supply, and configured to communicate AC power from the power source to the at least one receptacle according to whether the fault detector detects a fault, the power switch including a second current-controlled switch controlled by the first current-controlled switch;
a path to a ground connected to the at least one receptacle; and
a surge protector configured to operate in a first mode and a second mode, the surge protector including
a first electrical clamp connected between the line conductor and the neutral conductor, the first electrical clamp configured to limit the flow of current to the at least one receptacle when the surge protector is in the second mode of operation and a first voltage between the line conductor and the neutral conductor exceeds a first threshold value,
a second electrical clamp connected between the line conductor and the ground conductor, the second electrical clamp configured to limit the flow of current to the at least one receptacle when the surge protector is in the second mode of operation and a second voltage between the line conductor and the ground conductor exceeds a second threshold value,
a third electrical clamp connected between the neutral conductor and the ground conductor, the third electrical clamp configured to limit the flow of current to the at least one receptacle when the surge protector is in the second mode of operation and a third voltage between the neutral conductor and the ground conductor exceeds a third threshold value, and
a fourth electrical clamp configured to prevent a leakage current caused by the relocatable power tap from exceeding a current limit when the surge protector is operating in the first mode.
2. The relocatable power tap of claim 1 , wherein the fault detector is further configured to generate a human recognizable indication when no faults are detected.
3. The relocatable power tap of claim 2 , wherein the human recognizable indication is light generated by a light emitting diode.
4. The relocatable power tap of claim 1 , wherein the power switch includes a normally-open switch.
5. The relocatable power tap of claim 3 , wherein the power switch includes at least one relay.
6. The relocatable power tap of claim 1 , wherein the power supply includes a half-wave rectifier.
7. The relocatable power tap of claim 1 , wherein the power supply includes one or more series connected diodes.
8. The relocatable power tap of claim 1 , wherein the fault detector is further configured to drain a leakage current to ground.
9. The relocatable power tap of claim 1 , wherein the current limit is 100 micro-amperes or less.