Abstract A bushing current transformer is provided and includes an auxiliary current transformer mounted on the top of a bushing. The primary and secondary coils of the auxiliary current transformer are connected parallel to each other and in series to an electrical power line having a high voltage and carrying a high current therethrough. A conductive lead is connected to the secondary coil of the auxiliary current transformer and is conducted to the bottom of the bushing to thereby form a primary coil of a main current transformer which is positioned on the bottom of the bushing and then conducted upwards again through the bushing. With such an arrangement the size of the line conductor being introduced into the bottom of the bushing can be made smaller, since the current transformation ratio between the primary and secondary coils of the auxiliary current transformer can be adjusted. Also, the current transformer can be standardized and thereby adapted for mass production due to the ability to fix the secondary current of the auxiliary current transformer at a constant amplitude.
An upright type bushing current transformer comprising: a casing; a main current transformer mounted in said casing and having an iron core with a primary and a secondary coil wound thereon: an upright bushing mounted on said casing; an auxiliary current transformer mounted on the top of said bushing and having an iron core with a primary and a secondary coil wound thereon, the windings being in opposite directions and said primary and secondary coils of said auxiliary current transformer being connected in parallel with each other and being connected in series to an electrical power line; and, a conductive lead connected to said primary of said main transformer and said secondary of said auxiliary transformer and extending through said bushing for enabling energization of the primary coil of said main current transformer in accordance with the current of the secondary coil of said auxiliary current transformer.
Claim 2
Dependent Claim
147 words
An upright type bushing current transformer comprising: a casing; a main current transformer mounted in said casing and having an iron core with a primary and a secondary coil wound thereon: an upright bushing mounted on said casing; an auxiliary current transformer mounted on the top of said bushing and having an iron core with a primary and a secondary coil wound thereon, the windings being in opposite directions and said primary and secondary coils of said auxiliary current transformer being connected in parallel with each other and being connected in series to an electrical power line; and, a conductive lead connected to said primary of said main transformer and said secondary of said auxiliary transformer and extending through said bushing for enabling energization of the primary coil of said main current transformer in accordance with the current of the secondary coil of said auxiliary current transformer.
Claim 3
Dependent Claim
24 words
An upright type bushing current transformer according to claim 1, wherein said auxiliary current transformer is removably mounted on the top of said bushing.
Claim 4
Dependent Claim
33 words
An upright type bushing current transformer according to claim 1, wherein said secondary coil of the auxiliary current transformer includes at least one intermediate tap for enabling different current transformations to be realized.
Claim 5
Dependent Claim
35 words
An upright type bushing current transformer according to claim 1, wherein said secondary coil of the auxiliary current transformer includes at least two coil elements which may be connected either in series or in parallel.
Claim 6
Dependent Claim
29 words
An upright type bushing current transformer according to claim 1, wherein said secondary coil of the auxiliary current transformer includes a second auxiliary current transformer connected in series thereto.
Claim 7
Dependent Claim
42 words
An upright type bushing current transformer according to claim 1, wherein at least one of said primary and secondary coils of said auxiliary current transformer includes an impedance element connected thereacross for enabling a fine adjustment of the current transformation to occur.