Overvoltage protection for HV bushing test tap
A protection device configured for being electrically connected to a test tap of a HV bushing for protecting the bushing from transient overvoltages. The protection device includes at least two parallel connected protection branches connected between the test tap and a ground connector configured for connecting to ground. Each of the protection branches includes a plurality of parallel connected gas discharge tubes, a Transient-Voltage-Suppression (TVS) diode connected in series with the gas discharge tubes, and a resistor connected in series with the gas discharge tubes and across the TVS diode.
1. A protection device configured for being electrically connected to a test tap of a high-voltage (HV) bushing for protecting the bushing from transient overvoltages, the protection device comprising:
at least two parallel connected protection branches connected between the test tap and a ground connector configured for connecting to ground;
each of the at least two protection branches comprising:
a plurality of parallel connected gas discharge tubes (GDTs);
a Transient-Voltage-Suppression (TVS) diode connected in series with the gas discharge tubes; and
a resistor connected in series with the gas discharge tubes and across the TVS diode.
2. The protection device of claim 1 , wherein the TVS diode has a breakdown voltage which is higher than an ignition voltage of the GDTs.
3. The protection device of claim 1 , wherein the at least two parallel connected protection branches comprises four parallel connected protection branches.
4. The protection device of claim 1 , wherein the plurality of parallel connected GDTs comprises three parallel connected GDTs.
5. A HV bushing comprising:
a test tap; and a protection device of claim 1 connected to the test tap.
6. An electrical system comprising:
an electrical device; and the bushing of claim 5 arranged through a wall of a housing of the electrical device.
7. The electrical system of claim 6 , further comprising a measurement equipment connected to the test tap via an electrical conductor.
8. The protection device of claim 1 , wherein each GDT of the plurality of GDTs has an ignition voltage, and
wherein the TVS diode has a breakdown voltage greater than the ignition voltage of the plurality of GDTs.
9. The protection device of claim 1 , wherein the plurality of protection branches comprise four protection branches.
10. The protection device of claim 9 , wherein, for each protection branch of the plurality of protection branches, the plurality of GDTs comprises three GDTs.
11. The protection device of claim 1 , wherein, for each protection branch of the plurality of protection branches, the plurality of GDTs comprises three GDTs.
12. The HV bushing of claim 11 , wherein the resistor and the TVS diode are connected in parallel between the intermediate node and the ground connector.
13. The HV bushing of claim 11 , wherein each GDT of the plurality of GDTs has an ignition voltage, and
wherein the TVS diode has a breakdown voltage greater than the ignition voltage of the plurality of GDTs.
14. The HV bushing of claim 11 , wherein the plurality of protection branches comprise four protection branches.
15. The HV bushing of claim 14 , wherein, for each protection branch of the plurality of protection branches, the plurality of GDTs comprises three GDTs.
16. A protection device for a high voltage (HV) bushing, the protection device comprising:
a plurality of protection branches connected in parallel between a test tap of the HV bushing and a ground connector,
each protection branch of the plurality of protection branches comprising:
a plurality of gas discharge tubes (GDTs) connected in parallel between the test tap and an intermediate node;
a Transient-Voltage-Suppression (TVS) diode connected in series between the intermediate node and the ground connector; and
a resistor connected in series between the intermediate node and the ground connector.
17. The protection device of claim 16 , wherein the resistor and the TVS diode are connected in parallel between the intermediate node and the ground connector.
18. A HV bushing comprising:
a test tap;
a ground connector; and
a protection device connected between the test tap and the ground connector, the protection device comprising:
a plurality of protection branches connected in parallel between the test tap and the ground connector,
each protection branch of the plurality of protection branches comprising:
a plurality of gas discharge tubes (GDTs) connected in parallel between the test tap and an intermediate node;
a Transient-Voltage-Suppression (TVS) diode connected in series between the intermediate node and the ground connector; and
a resistor connected in series between the intermediate node and the ground connector.
19. An electrical system comprising:
an electrical device comprising a housing, the housing comprising a wall; and
the bushing of claim 18 arranged through a wall of the housing of the electrical device.
20. The electrical system of claim 19 , further comprising a measurement equipment electrically connected to the test tap.