US1638533A - Protective device for use in polyphase-current installations - Google Patents

Description

1,638 Aug. 9, 1927. I R. KELLER ,533

PROTECTIVE DEVICE FOR USE IN POLYPHASE CURRENT INSTALLATIONS Filed Nov. :5. 1925 Patented Aug. 9, 1927.

UNITED STATES PATENT OFFICE.

ROBERT KELLER, OF ENNETBADEN, SWITZERLAND, ASSIGNOR T0 AKTIENGESELL- SCHAIT BROWN BOVERI AND DIE, 0F BAIDEN, SWITZERLAND.

PROTECTIVE DEVICE FOR USE IN POLYPHASE-CUBRENT INSTALLATIONS.

Application filed November 3, 1925, Serial No. 68,617, and in Germany November 17, 1924. i

operation when a certain load has been attained and reducing the exciting current of the generators supplying the installation, so that the output is reduced to normal. In polyphase current installations however there is a disadvantage in that the effect of the overload on the regulator varies according to the nature of the overload, i. e.,

whether it occurs on one, two or all the.

phases.

This disadvantage is overcome by the present invention which ensures that the regulator shall operate whether the current exceed the limit in one, two or all the phases and whether the currents be leading, lagging or in phase. The object of the invention is attained by providing as many electrically separate magnetic devices as' there are phases,-- each of the devices acting independently on the control member of the regulator.

Forms of the invention will now be described with reference to the accompanying drawings wherein Fig. 1 shows diagrammatically one arm bodiment of the invention, and

Fig. 2 shows diagrammatically a second form of the invention.

Figures 3 and 4 illustrate diagrammatically two further embodiments of the invention.

In the embodiment of the invention diagrammatically illustrated in Fig. 1 a is a resistance inserted in the field circuit of theexciter c of the polyhasc generator I). This resistance is controlled by a member (5 which normally occupies a position in which the resistance a is short circuited thereby. The member d is held in the position mentioned by a sprin f. The member d carries a plate e w ich' occupies a position opposite to, but separate from, the armature of an electromagnet g and the ends of two two-armed levers m, n. The levers m, n 'are connected with and operated by the armatures of electromagnets h, i, respective ly. k, is, k are tension springs which act of the phases, say,

.on the armatures of the electromagnets R, S, T.

'The operation of the device is as follows If, for example, an overload occurs in one in. phase S, the electro-. magnet z' is energized to actuate the lever m which strikes and raises the plate e and with it the member 05. The short circuit on the resistance a is removed, wholly or partly, the exciting current is reduced and the potential of the generator 6 falls. In the case of an overload of equal amount in two or all the phases, the electromagnets energized b the said phases are caused to 0perate t e member d. In order that the pressure on the plate e may be kept practically equal in the case of an overload on one two or all the phases the spring 7'- is ma e as weak as possible in relation to the pull of the electromagnets g, h, i.

Fig. 2 illustrates diagrammatically another embodiment of the invention in which the electromagnets g', h, 11, act on Ferraris discs p. The discs p are also influenced by springs k which normally hold them against a stop g. Now if the current, for example, in phase B exceeds the predetermined limit, the disc 12 rotates, together with a toothed segment 0", against the pull of the spring is in the direction indicated by the arrow. The toothed segment 1- meshes with a toothed wheel a loosely mounted on the shaft 0 of the regulator. When the toothed wheel s has rotated through a predetermined angle, a pin t mounted on the toothed wheel 8 comes in contact with a lever a mounted on the shaft e of the regulator. The shaft of the regulator is connected with a contact segment at and this contact segment d is operated and is moved in a direction to insert resistance a into the field circuit of the exciter when the lever u is acted on by the pin 6.

Referring to Figs. 3 and 4, when an overload occurs on one, two or all of the phases, a SWlLLJAl 1) is operated by the electromagnet or electromagnets that is or are energized to actuate. The switch 4) controls the circuit of the regulator 10. In the embodiment illustrated in Fig. 3, when an overload occurs on one or more of the phases, the armature of one or more of the electromagnets. g, h, i strikes the switch plate f and closes switch '0. The closing of switch '0 places the vibrator coil of the Tyrrill Regulator w in circuit and the field current of the exciter is weakened.

In the embodiment illustrated in Fig. 4, the switch a; is opened on an overloa by at least one of the electromagnets g h, z, and the holding-on coil 1) of the switc arm az' is de-energized. The switch arm a: is released and as it moves resistance a is inserted into the field circuit of theexciter.

The devices shown act equally well on single base circuit as on a two-phase or a three-p ase circuit.

What I claim is 1. Means for controlling overloads in poly h lnSt8 .llB.tl0nS comprising a single regu at member to control the current supplied y the generator, a plurality of electrically separate electromagnetic devices connected one in each phase and an operative connection between each electromagnetic device and the regulating member.

2. Means for controlling overloads in poly hase installations comprising a single regu ating member to control the current supplied the generator, a plurality of electrically separate electromagnetic devices, a plurality of current transformers -connected one infeach phase with each secondary connected to a separate electromagnetic device, and an operative connection between each electromagnetic device and the regulating member.

3. Means for controlling overloads in poly hase installations comprising a single regu ating member to control the current.

supplied by the generator, a plurality of electricallyse arate electromagnetic devices one connecte in each phase and each controlled by a-separate spring and an operative connection between each electromagnetic device and,the regulating member.

4. Means for controlling overloads in poly hase installations comprising a single regu atin member to control the current supplied y the generator, a plurality of electrically separate electromagnetic devices each controlled by a separate spring, a plurality of current transformers connected one in each phase with each secondar connected to a separate electromagnetic. evice and an operative connection between each electromagnetic device 'and the regulating member.

5. Means for controlling overloads in polyphase installations comprising a single regu atin member to control the current supplied y the generator, a plural1ty of electrically separate electromagnetic devices connected one in each phase, and an opera tive connection between each electromagnetic device and the regulating member having a time lag between the commencement of operation of the electromagnetic device and its action on the regulating member.

6. Means for controlling overloads in polyphase installations comprising a single regu ating member to control the current supplied by the generator, a plurality of electrically separate electromagnetic devices, a plurality of current transformers connected one in each phase with each sec-.

to vary the amount of said resistance con- I nected in the circuit, a plurality of electrically separate electromagnetic devices connected one in each phase of the polyphase installation, and an operative connection between each electromagnetic device and the means to vary the amount of the resistance connected in the circuit.

8. Means for controlling overloads iii polyphase installations comprising a resistance connected in the field circuit of the exciter of the polyphase generator, means to vary the amount of said resistance connected in the circuit, a plurality of electricall separate electromagnetic vdevices, a plura ity of current transformers connected one in each phase with each secondar connected to a separate electromagnetic evice and an operative connection between each electromagnetic device and the means to vary the amount of the resistance connected in the circuit.

9. Means for controlling overloads in polyphase installations com rising a resistance connected in the field circuit of the exciter of the polyphase nerator, means to vary the amount of saitf resistance connected in the circuit, a plurality of electrically separate electromagnetic devices connected one in each phase of the polyphase installation, and an operative connection between each electromagnetic device and the means to vary the amount of the resistance having a time lag between the commencement of operation of the electrmagnetic device and its action on the means to vary the amount of the resistance.

10. Means for controlling overloads in polyphase installations comprising a resistance connected in the field circuit of the exciter of the polyphase generator, means to var the amount of said resistance connected in the circuit, a plurality of electrically separate electromagnetic devices, a plurality of current transformers connected, one in each phase with each secondar connected to a separate electromagnetic evice, and an operative connection between each elec tromagnetic device and the means to vary the amount of the resistance havin a time lag between the commencement 0 operation of the electromagnetic device and its action on the means to vary the amount of the resistance.

11. The combination with a polyphase penerator having a field wind' of a reguator for controlling the current m said field

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