Phase-to-phase surge protective devices

Abstract

A surge protector having a hot line, a load line, a neutral line, and a ground line, the surge protector is provided. The surge protector has a fuse coupled between the hot line and the load line to protect loads from current surges. A differential mode protection circuit is coupled between the load line and the neutral line to protect loads from differential mode transient voltage surges. A common mode protection circuit is coupled to the load line, the neutral line and the ground line to protect loads from common mode transient voltage surges. An indicator circuit monitors the differential mode protection circuit and the common mode protection circuit to provide an indication as to the operational status of the surge protector.

What is claimed is: 
     
         1 . A surge protector having a hot line, a load line, a neutral line, and a ground line, the surge protector comprising:
 a fuse coupled between the hot line and the load line;   a differential mode protection circuit coupled between the load line and the neutral line; and   a common mode protection circuit coupled to the load line, the neutral line and the ground line.   
     
     
         2 . The surge protector of  claim 1 , further comprising an indicator circuit coupled at least between the load line and the neutral line and capable of indicating an operational status of the surge protector. 
     
     
         3 . The surge protector of  claim 2 , wherein the indicator circuit comprises an indicator configured to activate when the surge protector is operational. 
     
     
         4 . The surge protector of  claim 3 , wherein the indicator comprises at least one of a visible indicator, a light source and an audible indicator. 
     
     
         5 . The surge protector of  claim 1 , wherein the differential mode protection circuit comprises at least one surge suppressor coupled between the load line and the neutral line. 
     
     
         6 . The surge protector of  claim 1 , wherein the at least one surge suppressor comprises a varistor. 
     
     
         7 . The surge protector of  claim 6 , wherein the varistor comprises a metal oxide varistor. 
     
     
         8 . The surge protector of  claim 1 , wherein the common mode protection circuit comprises at least one surge suppressor between the load line and the ground line. 
     
     
         9 . The surge protector of  claim 8 , wherein the at least one surge suppressor comprises a varistor. 
     
     
         10 . The surge protector of  claim 9 , wherein the varistor comprises a metal oxide varistor. 
     
     
         11 . The surge protector of  claim 8 , wherein the at least one surge suppressor comprises a gas discharge suppressor. 
     
     
         12 . The surge protector of  claim 11 , wherein the gas discharge suppressor comprises a gas discharge tube. 
     
     
         13 . The surge protector of  claim 1 , wherein the common mode protection circuit comprises at least one surge suppressor between the neutral line and the ground line. 
     
     
         14 . The surge protector of  claim 13 , wherein the at least one surge suppressor comprises a varistor. 
     
     
         15 . The surge protector of  claim 14 , wherein the varistor comprises a metal oxide varistor. 
     
     
         16 . The surge protector of  claim 13 , wherein the at least one surge suppressor comprises a gas discharge suppressor. 
     
     
         17 . The surge protector of  claim 16 , wherein the gas discharge suppressor comprises a gas discharge tube. 
     
     
         18 . The surge protector of  claim 1 , further comprising an indicator circuit coupled at least between the load line and the neutral line and having a transmitter capable of transmitting a signal indicating an operational status of the surge protector. 
     
     
         19 . A surge protector having a hot line, a load line, a neutral line, and a ground line, the surge protector comprising:
 a fuse coupled between the hot line and the load line;   a differential mode protection circuit coupled between the load line and the neutral line, the differential mode protection circuit having at least one surge suppressor coupled between the load line and the neutral line; and   a common mode protection circuit coupled to the load line, the neutral line and the ground line;   wherein the common mode protection circuit includes:
 a first surge suppressor coupled between the ground line and an intermediate node; 
 a second surge suppressor coupled between the load line and the intermediate node; and 
 a third surge suppressor coupled between the neutral line and the intermediate node. 
   
     
     
         20 . The surge protector of  claim 19 , further comprising an indicator circuit coupled between the load line and the neutral line and capable of indicating an operational status of the surge protector. 
     
     
         21 . The surge protector of  claim 20 , wherein the indicator circuit comprises a substantially DC power source and an indicator configured to activate when the surge protector is operational. 
     
     
         22 . The surge protector of  claim 20 , wherein the indicator circuit comprises a substantially DC power source and an indicator configured to activate when the surge protector is not operational. 
     
     
         23 . The surge protector of  claim 19 , wherein the first surge suppressor, the second surge compressor and the third surge suppressor each comprise at least one of a varistor and a gas discharge suppressor. 
     
     
         24 . The surge protector of  claim 19 , further comprising an indicator circuit coupled at least between the load line and the neutral line and having a transmitter capable of transmitting a signal indicating an operational status of the surge protector. 
     
     
         25 . A surge protection device, comprising
 a housing;   a hot line, a load line, a neutral line, and a ground line;   a fuse coupled between the hot line and the load line;   a differential mode protection circuit coupled between the load line and the neutral line; and   a common mode protection circuit coupled to the load line, the neutral line and the ground line.   
     
     
         26 . The surge protection device of  claim 25 , further comprising an indicator circuit coupled at least between the load line and the neutral line and capable of indicating an operational status of the surge protection device. 
     
     
         27 . The surge protection device of  claim 26 , wherein the indicator circuit comprises an indicator configured to activate when the surge protection device is operational. 
     
     
         28 . The surge protection device of  claim 26 , wherein the indicator circuit comprises an indicator configured to activate when the surge protection device is not operational. 
     
     
         29 . The surge protection device of  claim 25 , wherein the differential mode protection circuit comprises at least one surge suppressor coupled between the load line and the neutral line. 
     
     
         30 . The surge protection device of  claim 29 , wherein the at least one surge suppressor comprises a varistor. 
     
     
         31 . The surge protection device of  claim 25 , wherein the common mode protection circuit comprises at least one surge suppressor between the load line and the ground line. 
     
     
         32 . The surge protection device of  claim 31 , wherein the at least one surge suppressor comprises a varistor. 
     
     
         33 . The surge protection device of  claim 25 , wherein the common mode protection circuit comprises at least one surge suppressor between the neutral line and the ground line. 
     
     
         34 . The surge protection device of  claim 25 , further comprising an indicator circuit coupled at least between the load line and the neutral line and having a transmitter capable of transmitting a signal indicating an operational status of the surge protection device. 
     
     
         35 . The surge protector of  claim 1 , further comprising a second fuse, coupled in the neutral line, adjacent to the neutral terminal connection.