US2117583A - Electrical transformer - Google Patents

Description

May 17, 1938 G. s. VAN ANTWERP ELECTRICAL TRNSFORMER Filed Aug. le, 1955 .3/ immun 1 Glad/fa@ $272,577 10H70 p fans iwf/V565! W...

lMay 17, 1938. G. s. VAN ANTWERP ELECTRICAL TRANSFORMER Filed Aug. 16, 1935 2, Sheets-Shea?, 2

w, M m M iw M M HES- ya. G J P. s M x 8 7 A5 lvxOv 0 www: mw 4/ M M l o w48 4 3 2 5/ ,hnhlhhuuflnwuu 2 3.2 3 3 Cl -,---H 5. l 3 lllllf 6 o lo O 2 YM F @ao Patented May 17, 1938 UNITED STATES .PATENT oFFicE ELECTRICAL mANsFonMsn c George S. Van Antwerp, Norristown, Pa.

Application num: 1s, i935, serial No. 36,511

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and more eil'ective, and in which the operation I is more perfect and the protection given is more satisfactory, than heretofore.

lo Other objects are to dispense with the use of .cross arms on the poles las a means for suspending the transformers; to provide an overload cut-out manually or automatically operated; toA

provide that a fuse shall blowin oil; to utilize l the primary circuit in the automatic operation of the overload cut-out; to operate the overload cut-out in differential response to both the current in the primary circuit and to the sensible temperature of the loil; to simplify the construction of the tank and avoid the necessity for pockets in it; to improve the construction, arrangement and operation of the fuse holder and to conveniently locate the lightning arrester at the outside of the tank. Other objects of the invention will appear from the following description at the end of which the invention will be claimed.

Generally stated the invention comprises a cylindrical tank provided with a T-slot suspension and with an insulating fuse holder detachably mounted at its top and including a lightning arrester, and the interior of the tank containing an oil supply and a frame submerged in the oil4 supply and arranged above the transformer coils and core, and externally of the tank there being provided a manual handle for operating a cut-out switch arm that breaks the primary circuit beneath the oil and serves to lock and unlock the fuse carrier and there is optionally provided a spring tending to throw the switch arm out and 1 an electro-magnetic catch for detaining the spring, the electro-magnetic catch being operated by differential thermostats of which one is immersed in the oil and responds to its temperature, and of which the other is included in the primary circuit of the transformer, said thermostats controlling the circuit of the electro-magnetic catch.

The invention also comprises the improvements to be presently described and iinally claimed.

Referring to the drawings, Figure 1 is a view partly in section and partly in elevation illustrating the upper portion of a .transformer embodying features of the inven- -(Cl. F- 294) y tion' and diagrammatically showing the transformer coils.

Figure 2 is a sectional view taken on the line 2 2 of Figure 1.

Figure 3 is a view partly in section on the line .5

, 3 3 of Figure 1 and partly in elevation.

Figure 4 is a view drawn to a reduced scale and illustrating the transformer in application to a pole, and

Figure 5 is a side view of the transformer shown 10 in Figure 4.

Referring to the drawings, I is a tank of metal shown as externally provided with a channelpiece 2 having a T slot 3 formed therein. The channel piece 2 is provided with pivotal extenl5 sions 4. This 'construction enables the transformer tank to be suspended in a readily detachable manner from a through bolt 5 extending through the pole. The channel piece finds a good support in respect to the pole and the extensions 4 may be employed as additional means for preventing the tank from swaying. The lid 6 of the tank is provided with a drip skirt and is shown as bolted to a flange at the top of the tank with the interposition of a gasket 1. Thus the interior of the tank is protected from the weather. The .tank contains oil, the level of which is indicated at the line :zt-11:. The tank also contains at the lower part thereof the core and the primary and secondary windings. The 3 primary winding is indicated at b and the secondary winding is indicated at c and c. 8 is a frame extending across the tank with space on each side of it. 9 is an insulator shown as cylindrical and it is detachably mounted on the 35 ltop of the tank by means of a threaded metal ring I0 having screw threaded engagement with a metal neck II on the top 6 of the tank. Thus the cylindrical insulator 9 can be shipped detached from the tank and readily mounted in 40 place. Use may be made of a closure I2 (Figure 5) for retaining the oil when the tank is shipped. 'I'he insulator 9 is fitted with spring contacts I3 and Il (Figure 2) and the contact I3 is connected with the high tension line I5. The con- 45 tact I4 is connected with the conductor I6 of the lightning arrester I'I of which the other conductor or terminal I9 is connected with the ring IIl and. through the tank to ground. The cap I9 is shown as provided with a handle 20 and it 50 is mounted on top of the insulator 9. The cap detachably carries a fuse and is in fact a fuse holder. The fuse includes a metallic head 2| having contact blades which are engaged by the contacts I3 and I4. The fuse alsor includes an u insulating tube 22 and 23 and at the lower end there is a metallic foot 24 having an insulating tip 251i The insulating tip 25 is seated in an aperture provided in the frame 8. The fuse proper 2B extends from the head 2i to thc foot 24 and is included in the primary circuit of the transformer. The foot 2d is immersed in the oil. 21 is a handle turnably mounted and accessible from the exterior oiJ the tank. 2li is a switch arm turnabie with the handle and provided with a bridge contact 29 adapted to be interposed in the primary circuit Sil. It bridges the circuit between the conducting post 3i and the metal :toot it may be remarked that when the bridge 29 is in position for closing the primary circuit the fuse may not be withdrawn because the bridge overlies the foot 2li. The purpose of this is to ensure that the cap iii and the fuse may not be withdrawn until after the primary circuit is broken, and it is broken in oil just as the fuse blows in oil. There is a spring 32 tending to turn the switch arm riti into off position. rhis spring is set when the switch is closed and it is held in set position by a latch operating upon a keeper 3ft. As shown the spring is a spiral spring wound around the shaft Sli and having one end connected with the keeper Sil and the other end connected with an adjustable tension device 35. The keeper 35i is turned to set the spring by a iinger dii fast on the shaft Sila and when released the keeper 3G shifts the ringer Sii and with it the switch arm i253. The latch 33 is spring pressed and is part of an electro-magnetic device of which 3l is the solenoid. It will be understood that when the switch arm is turned to closed position the lnger 3G shifts the keeper to latched position provided that it is not already in latched position and when the keeper is released by the catch it turns the finger and with it the switch arm 2Q into open position. There are loi-metallic thermostats il@ and 39 mounted on the irme t and immersed in the oil. Between these thermostats are contacts for closing the circuit through the electro-magnet 3l. The thermostat 3S responds to the temperature o the oil. The thermostat 381s in the primary circuit and is grounded by way oi conductors 38 and fit. The thermostat is provided with a jacket di made in similitude to the winding on the transformer coil h and it is heat insulated. The thermostat 3d is heated by the current in the primary circuit to substantially the same extent that the primary coil is heated. By the diierential action of these thermostats the circuit through the electro-magnetic latch is closed permitting the switch arm 28 to be cut-out. in the event that the transformer, due to the load being carried, has increased the oil temperature, the thermostat 39 has partly closed and hence a short circuit or heavy load causes the thermostat 38 to function before damage is done to the transformer winding. if the oil is cold and a short circuit occurred the thermostat 3S will have comparatively4 far to travel and will consequently carry the load for a suicient length of time before tripping the cut-out switch 2S. In this way the thermostatic device is responsive to actual temperature conditions in the transformer and allows for the maximum carrying capacity of the winding of the transformer before tripping the switch arm 28. It is a feature that the switch arm 2li may be opened manually or automatically and it may be remarked that the provision for automatically opening the switch arm 28 may, if desired, be omitted. The center part of the secondary coil is grounded by 42 and 40 and the circuit for the electro-magnetic device 3l is from one end of the secondary by 43 and thence to ground by 39 when the contacts of the thermostats are closed. There are two leads for the secondary circuit of which one is shown at d4 and the other at @i5 and in the form of covered wires they are carried through insulating guide eyes i5 on the outside oi the tank i. 1t may be remarked that the tank is grounded and that the parts which carry current are insulated from the frame il.

The tank structure and its accessories and the electrical provisions are dependent upon each other and contribute to the improved result oi the described transformer which invoives not only safety in the distribution of high tension current but also convenience and safety in manipulation by those who have to install and service the devices on poles in all sorts or conditions of weather.

Oil may find its way into the lower part of the fuse tube 23, and when 'the iuse blows, ii7 there is an explosion, it occurs remote from the gas space above the oil line and is vented through the notch lil and by the lifting of the cap it will be obvious to those skilled in the art to which the invention relates that modiications may be made in details of construction and arrangement without departing from the spirit or the invention, which is not limited as to such matters or otherwise than the priorart and the appended claims may require.

I claim:

i. In a transformer of the type specified the combination of a tank provided internally with primary and secondary windings and with a core, and containing oil, an insulator mounted on the top of the tank, a cap detachably mounted on the insulator and provided with a depending inse tube and a fuse having a metallic foot immersed in the oil, circuit connections from the primary circuit through the fuse to the foot, a handle turnably mounted and accessible from the exterior of the tank and having a switch arm in- -side the tank and in range of the foot. and a contact submerged in the oil and interposed in the primary circuit and disposed, in the path of the switch arm, said switch arm and themetailic foot on the fuse tube constructed and arranged to interlock when the arm is in closed position.

2. In a transformer of the type specified the combination of a tank provided internally with primary and secondary windings and with a core and containing oil, a cap provided with a depending fuse tube and fuse Ahaving a metallic foot in the oil, circuit connections from the primary circuit through the fuse to the foot, a handle' turnably mounted and accessible from the exterior of the tank and having a switch arm inside of the tank and in range of the foot, a contact submerged in the oil and disposed in the path of the switch arm and in the primary circuit, a spring and connections tending to turn the switch arm to ofi position, a keeper adapted to restrain the spring and permit free operation of the handle, an electro-magnetic latch for detaining the keeper, two thermostats having contacts and adapted to control the circuit of the electro-magnetic latch at a point submerged in the oil and of which one is responsive to the sensible temperature o the oil and of which the other is in the primary circuit and is responsive annees to current in the primary transformer coil, and a circuit connected to and controlled by the electro-magnetic latch and through the contacts of the thermostats.

3. Ina transformer of the type specied, the

combination of a tank provided internally with primary and secondary windings and with a core and containing oil, a frame submerged in the oil and provided with a contact included in the primary circuit andl with an aperture, a fuse provided with a fuse tube having a fuse included in the primary circuit and also having a metallic foot and an insulating tip adapted to seat in said aperture, a switch arm inrange of the contact and foot and having an operating handle exterior of the tank, a spring and its keeper adapted when the spring is released to throw out the switch arm, an electro-magnetic latch device for the keeper, two thermostats mounted on 4the frame and of which one is responsive to the temperature of the oil and the other to current in the primary coil of the transformer and is in series therewith, circuit connections through the electro-magnetic device and controlled by the diderential action of the thermostats, and circuit connections providing leads for said primary winding and for said secondary winding.

4. In a transformer of the type recited, the combination of a tank provided internally with primary and secondary windings and with a core and containing oil, a cap provided with a depending fuse tube and fuse having a metallic foot ,in the oil, a circuit connection from the primary circuit through the fuse to the foot, a handle turnably mounted and accessible from the exterior of the tank and having a switch arm inside of the tank and movable into and out of contact with the foot, a contact submerged in the oil and disposed in the path of the switch arm and connected to the primary winding, a spring and connections tending to turn the switch arm to ofi-position, an electro-mechanical latch device adapted to restrain the spring and permit free operation of the handle, two thermostats adapted to control the circuit of the electro-mechanical latch device and of which one is responsive to the sensible temperature of the oil and of which the other is in the primary circuit and is responsive to current in the primary transformer coil, and a circuitthrough the electro-mechanical latch device and connected to and controlled by the contacts oi' the thermostats.

5. In a transformer having primary and secondary windings, a tank suitable for enclosing the operating parts of the device and containing oil. a fuse tube supported by said tank and having a current-conducting portion projecting into l the exterior of said tank for moving said switch 6. In a transformer having primary and secondary windings. a tank forming a casing and containing o'il. a fuse tube having contacts `thereon of which one is`\beneath the oil in said tank, a

switch connected as to control the connections between said fuse tube and the primary winding, means operable from outside said tank and controlling said switch, a spring and connections tending to turn said means and said switch to disengaged position, a latch restraining said spring from operation, a thermostat responsive to the temperature of the oil in said tank, a contact with which the thermostat cooperates, and electromechanical means having a circuit controlled by the thermostat at the last mentioned contact and controlling the operation of said latch.

l 7. In a transformer having primary and secondary windings, a tank forming a casing and containing oil, a fuse tube having contacts thereon of which one is beneath the oil in said tank, a switch in said tank and connected so as to control the connections between said fuse tube and the primary winding, means operable from outside said tank and controlling said switch, a spring .and connections tending to turn said means and said switch to disengaged position, a latch restraining said spring from operation, a thermostat substantially heat insulated from the oil in said tank and responsive to the current in the primary winding and an electromechanical device having a circuit closed by the thermostat and controlling the operation of said latch.

8. In a protective system for an electric transformer, the combination of, a tank provided internally with primary and secondary coils and with a core co-operating with said coils and containing oill an insulator mounted on the tank, a lightning arrester mounted on the insulator and electrically connectedto the tank, a -fuse tube supported by said insulator and having a conducting portion projecting into the oil of said tank, a contact in said tank located adjacent said portion, a switch arm arranged for movement into and out oi' engagement with said contact and said portion and which, when in engaged position, locks said portion and consequently said fuse tube against removal from said tank, and means operable on the exterior of said tank for moving said switch arm. l

9. In a protective system for an electric transformer, the combination of, a tank containing oil and internally provided with primary and secondary coils and with a core co-operating with said coils, a hollow insulator mounted on said tank and having an outlet through one wall thereof, an imperforate cap detachably mounted on said insulator, a fuse tube mounted on said insulator and projecting through the hollow in said insulator, said fuse tube being provided with a vent adjacent said cap and communicating with the interior of said insulator, a metal foot mounted on said fuse tube in the oil in said tank, an electric connection mounted on said insulator and connected to said foot, a stationary contact mounted in the oil in said tan-k adjacent said foot, a metal bridge contact mounted for movement in said tank into and out of engagement with said foot and said stationary contact and arranged, when in engagement therewith, to lock said foot and consequently said fuse tube against removal from said tank, and means having a portion external to said tank for moving said bridge contact into and out of engaged position.

GEORGE 8. VAN AN'I'WERP.

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