Patent ID: 7372688

Claim:
A differential mode surge protection apparatus comprising: a. a first input connection point and a corresponding first output connection point; b. a second input connection point and a corresponding second output connection point; c. a first differential mode unipolar solid state protection device, wherein said first device is disposed in series between said first input connection and said first output point, whereby said first unipolar solid state protection device is disposed to operate to limit electrical current in only one direction from said first input point to said first output point; d. a second differential mode unipolar solid state protection device, wherein said second device is disposed in series between said second input connection and said second output point, whereby said second unipolar solid state protection device is disposed to operate to limit said electrical current in only one direction from said second input point to said second output point, whereas both said unipolar solid state protection devices are aligned to limit current in the same direction relative to said input and said output connections; and e. an isolating device connected between said first output connection and said second output connection, wherein said isolation device is a common mode protection device, whereas said unipolar solid state protection devices provide differential mode protection and said isolation device provides common mode protection.