Coupling arrangement for power line carrier systems

• US 4,066,912 A
• Filed: 04/21/1976
• Issued: 01/03/1978
• Est. Priority Date: 04/21/1976
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: General Electric Company
• Inventors: Wetherell, Daniel L.
• Primary Examiner(s): Hohauser, Herman
• Application Number:
  US05/678,962
• Time in Patent Office: 622 Days
• Field of Search: 307/3, 307/1, 307/2, 340/310 R
• US Class Current: 307/3
• CPC Class Codes: H04B 2203/5425 improving S/N by matching impedance, noise reduction, gain control
• CPC Class Codes: H04B 2203/5466 using three phases conductors
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 2203/5491 using filtering and bypassing
• CPC Class Codes: H04B 3/56 Circuits for coupling, blocking, or by-passing of signals

Abstract

First and second bands of separate frequencies are coupled through hybrid transformers and frequency isolation filters to each of three phase wires of a power transmission line. The hybrid transformers and filters are arranged so that both bands of frequencies are transmitted and received even though there is an open or short circuit on one of the feed lines or one of the phase wires, thus providing the reliability desired or needed, particularly when the frequency bands provide relaying functions.

Claims

1. An improved arrangement for coupling first and second separated frequency bands to each of first, second, and third phase wires of a power transmission line comprising:

a. a first hybrid transformer having an input for said first frequency band and first and second outputs coupled thereto;

b. a second hybrid transformer having an input for said second frequency band and first and second outputs coupled thereto;

c. a third hybrid transformer having an input coupled to said first output of said first hybrid transformer and having first and second outputs coupled thereto;

d. a fourth hybrid transformer having an input coupled to said second output of said second hybrid transformer and having first and second outputs coupled thereto;

e. first, second, and third filters for said first frequency band;

f. fourth, fifth, and sixth filters for said second frequency band;

g. means connecting said first filter between said first output of said third hybrid transformer and said first phase wire;

h. means connecting said second filter between said second output of said first hybrid transformer and said second phase wire;

i. means connecting said third filter between said second output of said third hybrid transformer and said third phase wire;

j. means connecting said fourth filter between said first output of said fourth hybrid transformer and said first phase wire;

k. means connecting said fifth filter between said first output of said second hybrid transformer and said second phase wire;

l. and means connecting said sixth filter between said second output of said fourth hybrid transformer and said third phase wire.

2. The improved arrangement of claim 1 wherein said first, second, and third filters pass substantially only said first frequency band, and wherein said fourth, fifth, and sixth filters pass substantially only said second frequency band.

3. The improved arrangement of claim 1 wherein said first, second, and third filters reject said second frequency band, and wherein said fourth, fifth, and sixth filters reject said first frequency band.

4. The improved arrangement of claim 1 wherein each of said hybrid transformers comprises a secondary winding having a center tap with an impedance matching resistor connected thereto.

5. An improved arrangement for coupling first and second separated frequency bands to each of first, second, and third phase wires of a power transmission line comprising:

a. a first hybrid transformer having an input for said first frequency band and first and second outputs coupled thereto;

b. a second hybrid transformer having an input for said second frequency band and first and second outputs coupled thereto;

c. a third hybrid transformer having an input and having first and second outputs coupled thereto;

d. first and second filters for said first frequency band;

e. third and fourth filters for said second frequency band;

f. means connecting said first filter between said first output of said first hybrid transformer and said input of said third hybrid transformer;

g. means connecting said third filter between said first output of said second hybrid transformer and said input of said third hybrid transformer;

h. means connecting said first output of said third hybrid transformer to said third phase wire;

i. means connecting said second output of said third hybrid transformer to said third phase wire;

j. means connecting said second filter between said second output of said first hybrid transformer and said second phase wire;

k. and means connecting said fourth filter between said second output of said second hybrid transformer and said second phase wire.

6. The improved arrangement of claim 5 wherein said first and second filters pass substantially only said first frequency band, and wherein said third and fourth filters pass substantially only said second frequency band.

7. The improved arrangement of claim 5 wherein said first and second filters reject said second frequency band, and wherein said third and fourth filters reject said first frequency band.

8. The improved arrangement of claim 5 wherein said hybrid transformers comprise a secondary winding having a center tap with a resistor connected thereto.