US1713214A - Transformer - Google Patents

Description

May 14, 1929. BRAND 1,713,214

TRANSFORMER Filed July 11, 1928 v Inventor:

Frederick FTBrand;

His Attorney Patented May 14, 1929'.

UNITED STATES 1,713,214 PATENT OFFICE.

FREDERICK 1. BRAND, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

TRANSFORMER.

Application filed July 11,

structed in accordance with the invention,

the windings being shown partially in section to reveal details.

The transformer shown in the drawing includes a magnetic core 1 of the usual three legged type with a central winding leg and two outer legs to provide return paths for the magnetic flux. The central winding leg is surrounded by a high voltage winding 2 having two end terminals 3 and 4 for connection to a high voltage outside circuit. The trans former operates as an autotransformer, the winding 2 having a third terminal 5 spaced from the end terminal 3 to give the desired voltage for a low voltage outside circuit connected to the terminals 3 and 5. The end terminal 3 is grounded.

- An intermediate point, preferably the center, of the winding 2 is connected to the core 1 by a connection 6 so that the potential of the core is the same as that point in the high voltage winding 2 to which it is connected. -The core must, of course, be insulated from ground for this voltage.

The winding 2 has a common section between the terminals 3 and 5 and a series section between the terminals 4 and 5. The turns of the winding are arranged along the winding leg of the core substantially in the order of increasing voltage from the low voltage or grounded terminal 3 to the high voltage terminal 4. This arrangement avoids high voltage and the necessity for excessive insulation between adjacent turns and coils of the winding but results in a wide separation of the common and series sections of the winding. To avoid an otherwise excessively high reaction between the common and series sections of the winding 2, there is,provided a coupling winding having two sections 7 and 8 surrounding the winding leg'of the core and which are connected in series by the conductors 9 and 10. The section 8 of the cou- 1928. Serial No. 291,988.

pling winding surrounds the winding leg of the core between it and the high voltage windmg 2 so that this section 8 of the coupling winding is closely coupled to the entire high voltage winding 2 including both its common and series sections. The section 7 of the coupling winding is located at the low voltage end ofthe high voltage winding 2 between the common section of the high voltage winding and the adjacent yoke of the core. This section 7 of the coupling winding thus provides additional magnetic coupling between the coupling winding and the common section of the main high voltage winding and therefore between the two sections of the high voltage winding.

The core 1 is connected by a conductor 11 to the coupling winding and preferably to an intermediate point at or near the center of this winding. This establishes the relative potentials of the core and the coupling winding, and limits the potential difference between them at any point to a small value because the voltage of the coupling winding itself may be small. Only a small amount of insulation is therefore necessary between the coupling winding and the core and also between the coupling winding and the central portion of the high voltage winding 2.

The voltage between the high voltage winding and the coupling winding and core increases gradually from a minimum at the center of the high voltage winding to a maximum at each end of the high voltage winding where this difference in voltage is equal to one half the total voltage of the high voltage winding. The insulation for the high voltage winding therefore tapers from a small amount at its center to a maximum at each end and may consist of a suitable arrangement of insulating cylinders 12 and end collars and flanges 13. It will be apparent that, even though one end of the high voltage winding be grounded no part of the entire transformer structure requires more insulation than is necessary for a voltage greater than one half that between the high voltage winding terminals. The arrangement is not only economical in insulation but the windings and core may be comparatively close together so that the reactance is small.

The invention has been explained by describin and illustrating a referred embodiment t ereof but it will e apparent that changes may be made without departing from the scope of the invention as defined in the appended claims.

What I claim as new and desired to secure by Letters Patent of the United States, 1s:

1. A transformer including a magnetic core having a high voltage winding, said winding having two end terminals and an intermediate terminal for autotransformer connection to two outside circuits, and an auxiliary winding magnetically coupling the common and series sections of said high voltage winding, said high voltage winding having one end grounded and an intermediate point-thereof conductively connected to said core. 7

2. A transformer including a magnetic core having a high voltage winding, said winding having two end terminals and an intermediate terminal for autotransformer' connection to two outside circuits, and an auxiliary winding magnetically coupling the common and series sections of said high volta e winding, one end of said high voltage winding being grounded, and said core being insulated from ground and conductively connected to an intermediate point of said high voltage winding.

1 3. A transformer including a magnetic core having a high voltage winding, said winding having two end terminals and an intermediate terminal for autotransformer connection to two outside circuits, and'an auxiliary winding conductively connected to said core and magnetically coupling the common and series sections of said high voltage winding, one end of said high voltage winding being grounded, and said core being insulated from ground and conductively connected to an intermediate point of said high voltage winding.

4, A transformer including a magnetic core having a high voltage winding, said winding having two end terminals and an intermediate terminal for autotransformer connection to two outside circuits, an auxiliary winding magnetically coupling the common and series sections of said high voltage winding, said auxiliary winding being conductively connected to said core and disposed between the core and said high voltage winding having one end grounded and an intermediate point thereof conductively connected to said'core, and insulation between said high voltage winding and said auxiliary winding and core, said insulation progressively increasing in amount from said intermediate point of the high voltage winding toward both ends thereof.

In witness whereof, I have hereunto set my

Images