DE421524C - Device for eliminating malfunctions caused by double earth faults in three-phase networks - Google Patents

Description

GERMAN EMPIRE

ISSUED NOVEMBER 13, 1925

REICH PATENT OFFICE

PATENT LETTERING

- JVr 421524 - ■ CLASS 21 c GROUP 57

VIII / 2ic ^{3 y}

Voigt & Haeffner Akt-Ges. in Frankfurt a. M. *).

Device for eliminating faults caused by double earth faults in three-phase networks. Patented in the German Empire on January 11, 1925.

In the case of extensive distribution networks: switch off. To now run the business as possible

it is often the case that one has been able to carry out undisturbed for a long time

existing earth fault at another point j it is necessary that from the earth faults to

of the network in another phase also j at least one is eliminated from the world,

a ground fault occurs and then all j thus the operation, even if one phase is on

between these two earth faults lies: earth lies, but can still be continued

endeavor immediately · can.

The following has been indicated by the patent seeker as the inventor:

P. v. d. Sien 'in Frankfurt a. M.

A solution to this problem is according to the invention through the use of voltage drop relays reached, which are normally due to the line-to-line voltage and one of which is switched to earth when an associated overcurrent relay responds, while at the same time one after the asymmetry circuit switched earth fault relay causes the connection to earth. The process is then ίο so that when you press the on Asymmetry responding earth fault relay and the corresponding overcurrent relay that one Voltage drop relay is drained that has been connected to earth, and in this way a switch, which is adjacent to one of the two ground faults, for Shutdown comes or in this way a piece of the network that has one earth fault is limited, switched off. A continuation

.20 drove with the second earth fault is generally harmless at first.

One of the possible circuit forms is shown in the drawing. It denotes α the switch with its overcurrent relays b and €. d \, e, f are three voltage drop relays, g the earth fault relay, which can be actuated by three current transformers in the lines R, S, T , which are connected in an asymmetrical circuit, and when switching the voltage drop relay / connects to earth, if the associated one Overcurrent relay c has determined by responding that there is an overload. The three voltage drop relays d, e, f work in a known manner according to the Ferraris principle. The disc r is driven by the coils m ¹ to m ⁴ , the coils m ¹ and m ^% as w? and m ⁴ are interconnected crosswise. Parallel to the coils m and ² m ^l is a resistor, "parallel to the coils m ¹ and m ³ ο a resistor. ρ is an auxiliary relay, q a weight connected to the Ferraris disc r , which gives contact for tripping when s. If the relay is energized, the resistance η gives the coils tri ² and m ^A a phase shift with respect to the coils m ¹ and m ³ in the sense of the clockwise movement of the Ferraris disk, the weight q is pulled up. If the overcurrent relay c responds, the auxiliary relay ρ receives current. The armature t is attracted and the voltage of the coils m ² and nz ⁴ is removed. The Ferraris-Sdheibe now rotates in the sense of draining, since the resistance ο has replaced the resistance η . At the same time, the coils m ¹ and m ^{3 act} with the parallel connected resistance ο in the braking sense against the tensile force of the weight q. After a time corresponding to the voltage drop, the weight q closes the contact s and the mains switch α is switched off. Once the short-circuit has been eliminated, the auxiliary relay ρ is de-energized, the weight q is pulled up, since a phase shift in the sense of clockwise movement has occurred again due to the resistance η. The operation of the voltage drop relays, which are connected to voltage as usual / in a delta connection, takes place in the normal way in such a way that the associated maximum relay responds in the event of an overcurrent or short circuit in one phase. All voltage drop relays begin to expire as all auxiliary relays receive ρ current. The voltage drop relay, the voltage of which has dropped due to the short circuit, will expire faster than the other two and cause the disconnected line to be switched off first. According to the invention, the overcurrent relay c is now provided with changeover contacts, whereby the voltage drop relay / belonging to the line R , which is connected to the voltage u / v, is switched off in the event of the earth fault relay g being switched from, ν and this terminal is connected to earth. Is in the line 5 at one point in the network and a ground fault at another point in the network, z. B. a ground fault in R ₁ , the relay c will switch over and switch the voltage drop relay / to earth. If an earth fault in 5 is accompanied by a further earth fault in T in the network, relay b will close and, when voltage drop relay d triggers, which is connected to earth via C , it will switch off, etc. ⁹ S

Claims (1)

Patent claim: Device for eliminating faults caused by double earth faults in three-phase networks using voltage drop relays characterized in that that in the event of an earth fault in two different phases by closing the contact of one lying in asymmetry Earth fault relay and closing of another with the contact of the earth fault relay series contact of a changeover switch through an overcurrent relay of a of the three voltage drop relays normally connected to linked voltage no with his one pole is connected to earth and this depends on the voltage drop against Earth causes the shutdown. 1 sheet of drawings.