DE1945803C3 - Circuit arrangement for monitoring the rotor circuit of DC machines - Google Patents

Description

The invention relates to a circuit arrangement for monitoring the rotor circuit of DC machines in terms of its insulation resistance to earth with a rotor circuit, a

1 S45 803

Secondary winding of a to feed a Hill- · Die VMilcr-.tand-.anoiduun, «der

* ·> !. ■ ·. hselspannuni..serving ifillstr.uisf'irniainr>. -.ίlicn Si haliiiiiusanordniinü contains advantage! ¹ .ifierwei-e one

on uic frequency of the auxiliary Wvvhsdspifnnuii.L away from the secondary winding of the! lilfsiraiiil '-. irniaior-

sliiniiMcn bandpass filter and an external part cuMiallciuicii fed further circuit. Since middle Jcr Widcr-

(Monitoring circle. Such a Schaliuiigsainudniin- "■ -tandsordnung significantly the Aiislöseverhahen the

gL-n are generally called Läufcr-ürdschiuilschniz i-.cii.iitΐιημ. arrangement, d. I '.. your address to one

designated. specific lsc.laiionswider-.tand is set are

In a known circuit arrangement of this would be the opponent in the resistance legs and to the several bandpass further upstream resistance voi-en Koiidensaio ^r arranged parallel to the direct current decoupling moderate, of which icweils m leilhafierweisi; adjustable. As a result, many are switched on, as is necessary with regard to the possibility of the tripping behavior of the animal eifmdiing Runner from the earth capacity possible:; · uninfluenced circular. adapt.
I. to be able to carry out monitoring. · .; The circuit means of the evaluating jil the invented

Furthermore, a device / for design-compliant circuit arrangements contain purpose- ■ • aehung of direct current circuits known (German idle, for example, differential transformers! Each with patent specification 666 203). where there are two primary windings and jev.ei! a secondary winding tapped in the middle next to the excitation winding of a three-phase generator, each with cMier downstream and an excitation machine as well as the secondary rectifier .chaluing. the success of an auxiliary transformer and an evaluation device work on a tripping element: through one part there is a bandpass filter that allows the auxiliary winding voltage to be matched to the frequency of such a configuration of the circuit means. This can be done with relatively little effort from the known device is not free from undesired DC circuit currents caused by the auxiliary AC voltage in the resistance influences by capacitances in the arrangement to be monitored and in the rotor circuit. men generate differential currents that are used to obtain

The invention is based on the object of a triggering signal being compared with one another in terms of amount in the triggering circuit arrangement for monitoring the rotor element. The circuit of DC machines is to be created with a primary winding of the one differential transformer wise high sensitivity, so that 30 mators in a branch with the bandpass filter and already insulation resistances to earth, which are smaller than the rotor circuit to be monitored and for example 5 kU can be detected. The other primary winding of this transformer should also be present in the rotor circuit or, together with the one primary winding, further interference voltages made possible by insulation faults. Differential transformer with the formation of the one that can be caused by rectifier excitation or rotating earth auxiliary circuit in series with which a resistor-U-circuit is not provided for the Bceinträch- branch of the resistor arrangement, while the operation is carried out. Furthermore, the invention is based on the task of creating a transformer circuit arrangement with the formation of the further aid for monitoring the rotor circuit of the direct current circuit with the other resistance branch of the machines, in which the balancing of the resistance arrangement is in series arranged isi.
Rätes largely insensitive to capacitance changes in the rotor circuit for evaluating the differential currents is: because, as is well known, the tripping circuit can be formed in different the earth capacitance of the rotor circuit not only from the on-way. For example, it can be a construction of the respective machine and the arrangement in relays with two windings,
It depends on a machine set, but depends on the temperature. circuit in the form of a resistor with downstream

To solve this problem, a circuit device is a current trigger, the current trigger being the preferred order a differential amplifier is arranged upstream to monitor the rotor circuit. This DC machines with regard to its isolation training the trigger circuit offers namely before resisted earth with a runner's circle. a 50 all the advantage that the comparison of the differential secondary winding one to feed in auxiliary currents is carried out quickly and thus also as an emergency voltage serving auxiliary transformer. a release signal is generated relatively quickly because matched to the frequency of the auxiliary AC voltage - the relatively long response times of th bandpass filter and an over-relay containing an evaluation part can not be disadvantageously noticeable, monitoring circuit suitable, in accordance with the invention in 55 In addition, such a trigger circuit is sensitive monitoring circuit in series with the bandpass filter more than a relay.

borrowed a fed from the auxiliary AC voltage in the circuit arrangement according to the invention

Resistance arrangement is arranged. the one from at least one on the frequency of the auxiliary exchange signaling

At least one of the secondary winding of the auxiliary trans- matched bandpass has to be avoided

formator's directly fed resistance branch to prevent harmful effects from overvoltage

generation of a comparative force and a tension such as this occur in the band, for example

there is a pass upstream resistor; the earth faults on the anode windings of direct

Distribution part shows switching steps! on which the Riehlertransformatoren on - proved to be advantageous,

the auxiliary alternating span in the resistor arrangement in the cross branch of the bandpass to connect a choke coil

niing generated comparison trol 'with that in the runner 65 arrange and dier.e so that they are in

circuit generated current;: to obtain a connection with a in the series branch of the bandpass

Trip signal when there is a sufficient difference between arranged, connected to the rotor circuit

compares both streams in terms of amount. Capacitor for direct current decoupling; ■ U. '

an overvoltage occurring in the monitoring circuit goes into Fcrrcrosonanz and thereby becomes effective for voltage limitation. In addition to this is / to prevent thermal overload in series with the bandpass filter, a primary winding of a protection handler and connected to the secondary winding of the torque converter a limit value indicator, when ferroresonance occurs in the choke coil, a damping resistor switches to initiates the monitoring circuit. The limit value indicator can advantageously influence a protective relay, by opening a contact that normally bridges the damping resistor switches on the attenuation monitor.

To despite switching on the damping resistor with the associated decrease in the current through the primary winding of the protective converter Command to maintain the current limitation or the excitation of the relay following the alarm indicator is expediently one in addition to the primary winding of the protective converter further primary winding provided; both primary windings are connected to each other at one end, and the common connection point is connected to the relay contact, so that the additional primary winding and the damping resistor existing series connection is parallel to the relay contact. This means that when the Damping resistance despite reduction of the current through the primary winding of the Sehutzvaiuller the excitation of the converter remains about the same, because '' 'e number of windings on the primary side I insciialten the further primary winding accordingly are increased. The protective relay remains picked up.

In order to avoid disruptive disruptions. z. B. with one of the frequency of the auxiliary AC voltage corresponding frequency and critical amplitude, to avoid, the of the Limit indicator activated protective relays advantageousvcise further contacts for switching off the evaluation part on. When critical interference voltages occur, the evaluation part becomes ineffective did.

Furthermore, it has proven to be advantageous when to Indication of the occurrence of critical interference voltages additional contacts of the protective relay signal lamps switch on and thus indicate that the erfindungsgcgenössc Circuitry currently not working effectively.

To explain the invention, FIG. 1 shows an exemplary embodiment of the hose assembly according to the invention shown, and Fig. 2 gives a preferred embodiment of an Ausvverteteiles again. 3 and 4 are to explain the mode of operation of the circuit arrangement according to the invention an equivalent circuit diagram and a diagram are shown.

If one first turns to Fig. I, one recognizes a circuit arrangement 5 which is connected to a rotor circuit of a DC machine to be monitored, which is marked by an insulation resistor RE and a capacitance CE to earth: the rotor circuit is connected to the circuit arrangement with a terminal Kl 5 connected, the other terminal A'2 of which is connected to earth.

The circuit arrangement S contains an auxiliary transformer Ht on the input side, the primary winding II '/) /) of which is connected to a voltage U. which is preferably identical to the mains voltage. The secondary winding of the auxiliary transformer IVsIi Hi is connected to a sound transmission point PX with a resistor arrangement IC and a circuit point Pl to a terminal point of an Al Auswertcteilcs AI.

The resistor arrangement IC contains a resistor branch with a resistor R1 and a further resistor branch with a resistor Λ3 and a resistor A1 in its series branch; the resistor Rl is connected to a connection point Al and the resistor Ri to a connection point A3 of the distribution part AT . At circuit points P3 and P4 is a tuned to the frequency of the voltage U band pass filter BP is connected to the resistor arrangement which contains in its longitudinal branch two inductors Ll and Ll and a capacitor Cl; the usual more capacity in the longitudinal branch of a bandpass filter is formed by a capacitor Cl which is connected to the terminal KX and a DC decoupling of the circuit 5 causes the rotor circuit Reice. In the transverse circle;.; A further inductance formed by a choke coil L3 and a capacitor C3 are arranged on the bandpass filter Bp.

Between the decoupling serving capacitor Cl and the band pass filter BP is arranged a protective converter .SH, which comprises two primary windings and WPSL H / w2 and a secondary winding Wss. The two primary windings Wpsl and Wpsl are each directly connected to one another at one end of the winding, and the common connection point PS is connected to a contact al of a protective relay A , which is connected to the output of a limit value indicator G connected to the secondary winding Wss of the protective converter SW. As can be seen from FIG. the contact «1 of the protective relay A normally bridges one primary winding H /> j2 of the protective converter SW and a damping resistor RcI lying in series with it. so that this damping resistor Rd in the de-energized state of the protective relay A is not effective. This changes when overvoltages occur, such as those that occur in the event of earth faults on the anode windings of rectifier transformers. In order to protect the circuit arrangement from hermic overload in this case, the power consumed is limited by switching on the damping resistor Rd , which is switched on automatically by means of the limit value indicator G with a protective relay A downstream. The command to limit the current is maintained by the primary winding Wpsl of the protective converter .SH ^, which is also switched on when the contact al is opened. Previously has become effective by the already guessed to the capacitor Cl in ferroresonance choke coil Z.3 the passband Bp voltage limiting.

As already stated above, the evaluation part AT is connected with its connection points AX to A3 with the secondary winding WsIi of the auxiliary transformer /// or with the resistor arrangement W : a further connection point A 4 of the Ausvverteteiles 47 "is directly connected to the circuit point PA connected to the grounded terminal Kl .

As shown in FIG. I, the evaluation part AT contains two differential transformers DTX and DTl on the input side, each of which has two primary windings WpXX and WpXl as well as WpIX and IFp22.

The primary winding WpIl of the one differential is a locus for the conductance 7} results with the

renz-Transform &'. ors DTl is identical with one end with circle GE / Gl . So if you choose a

connected to the connection point A4 , while you agreed circle GE / Gl = const as border line then

at the other end with the windings WpIl and Wp 11 , the decision »insulation is healthy or defective«

of the further differential transformer DTl in Ver 5 regardless of the capacity CE of the rotor circuit

binding stands. The other primary winding WpIl is against earth. The outer space of the border circle GK

on the one hand with one end of the winding WpIl and denotes the healthy one, the interior the defective one

on the other hand connected to the connecting point Al, isolation. Marked by the hands "21 and 03

while the primary winding WpIl to the connection conditions thus indicate a healthy insulation

points Al and A3 is connected. io by the resistor Rl (see. Fig. 1) is the

Both differential transformers DTl and DTl right intersection of the boundary circle GK with the

have a center-tapped secondary winding WsI real axis set, while the resistance

and WsI, the winding ends of which form A3 the center point M of the boundary circle GK and thus

It is a two-way rectifier circuit with rectifier the size of its diameter is determined

tern GIl and G12 or G21 and G22 are connected, 15 expediently, the resistors Rl and Λ3

the opposite direction to one of a relay B with two adjustable to run so in a simple way

Acting trigger circuit formed windings. by increasing or decreasing the resistance

This relay B closes in the event of a ground fault with values that allow the limit circle to be enlarged or reduced;

its contact b a circuit and thus gives a simple way of the response value

Trigger signal off. ao adjusted according to the respective circumstances

The circuit arrangement according to the invention works.

tet in the following way: In Fig. 2 is only one embodiment

From the auxiliary transformer Ht one of an evaluation part is constantly displayed. That on the input side

Auxiliary AC voltage Uh in the monitoring circuit turn two differential transformers DT3 and J

fed, whereby currents Jl and Jl on the as Dl4 containing evaluation part ATl is in the Zv.

Resistance branches with the resistors R1 and A3 in connection with the manner described in FIG. 1 practice;

flow to the evaluation part AT. In addition, flows into the connection points A 1 to A4 with the remaining parts

the evaluation part AT a current 73, the size of which depends on the circuit arrangement, such as the auxiliary transformer.

Insulation resistance RE in the rotor resistance arrangement to be monitored, bandpass filter and to be monitored

circuit of the DC machine is dependent. In the 30 the rotor circle, connected and points to the secondary

Evaluation part AT is made from the currents 71 to 73 of the differential transformers DT3 and DT *

Differential currents 73-71 and 72-71 formed; which in turn consist of rectifiers G31 and C32 as well

Differential currents can also be converted into a two-way rectifier circuit formed by the differences G41 and G42

<5 · Uh - \ / Rl · Uh and \ / R3 ■ Uh - \ / Rl ■ Uh prayers, which in the switching point /> 6 with each other

write, if with % the I eitwert according to Fig. 1 35 are connected. Between this switching point P6

or 3 is designated. Occurring on the secondary side and one with the center taps of the secondary

the two differential currents are rectified and windings Ws3 and Ws4 of the differential transform ³ -

act in opposite directions on relay B , which is located at point Pl connected to gates DT3 and DT4

The differential current 72-71 predominates because of the resistance Rm, which corresponds to the respective

characterized by defective insulation in the course of 40 strength of the differential transformers DT3

ferkreis responds and causes a trip. and DT4 differential currents emitted on the secondary side

The circuit arrangement according to the invention is based on a voltage Um drops. This voltage is based on the knowledge that, starting from this, a differential amplifier DV is controlled, which is followed by a current in the equivalent circuit diagram of the zj trigger St shown in FIG. Such a design of the monitoring rotor circuit and the bandpass-45 of the evaluation part is characterized by a ratio - CE in turn denotes the earth capacitance and RE the moderately high sensitivity and ensures insulation resistance in the rotor circuit, while Gp 1 bis a relatively fast triggering.

Gp3 the equivalent resistances of the bandpass filter. The invention is a circuit arrangement

Frequency of the auxiliary alternating voltage Uh , and Gl for monitoring the rotor circuit of direct current

the reciprocal of the resistance Rl is - a 50 machine created, which by an advantageously high

Conductance diagram <3 / Gl results, as it is marked in Fig. 4 sensitivity and the in their

is shown. This conductance mode of operation can be recognized by interference voltages due to direct

diagram that the curves 91 · C £ / GI = const and Richter excitation or rotating earth fault are not

G £ / Gl = const two orthogonally intersecting is impaired. In addition, the invention

Represent groups of circles. It can also be seen that 55 according to the circuit arrangement is unaffected by changes

at GE / Gl = const despite the change in the capacitance CE , the capacitance of the rotor circuit wrestled against earth.

1 sheet of drawings

Claims (1)

!> ■ 'uicnianspruchc: I. Circuit arrangement / for monitoring the rotor circuit of the DC machine)! in relation to: its insulation resistance to earth with a rotor circuit, a secondary winding of an auxiliary fan door serving to feed in an auxiliary AC voltage, a bandpass filter matched to the frequency of the auxiliary AC voltage and an evaluated monitoring circuit, thereby geke η η ζ calibration η ei that in the monitoring circuit a resistor arrangement (W) fed by the auxiliary alternating voltage (Uli ) is additionally arranged in series with the bandpass filter (Bp) . the other of at least one (of the secondary winding {Wsh) of the auxiliary transformer (Hi) gesp directly. ^ th resistive branch resistance Λ2) for generating a Vergleichsstromcs (Jl) and a the bandpass filter (bp) upstream resistor (Rl) ordered, and that the Has evaluated (.17 ") circuit means (DTl, DTl; GII to G22) which compare the comparative current (/ 1) generated by the auxiliary AC voltage (L '/;) in the resistor arrangement (II) with that in the rotor circuit (RE. CE) The amount of the induced current (J3) is compared with one another in order to obtain a tripping signal when there is a sufficient difference between the two currents (FIG. I). 2. Circuit arrangement räch A ipruch I. characterized in that the resistor arrangement contains a further resistance branch (resistor /? 3) fed by the secondary winding (It's /;) of the auxiliary transformer (Hi ) for generating a further comparison current (Jl) (Fig. I) ). 3. Circuit arrangement according to Claim I or 2, characterized in that the resistors (Rl. R3) in the resistance branches and the further resistor (Λ1) connected upstream of the bandpass filter (Bp) are adjustable (Fig. I). 4. Circuit arrangement according to one of claims I to 3, characterized in that the circuit means of the Ausvverteteils (AT) two differential transformers (DTl: DTl) each with two primary windings (M / Ml. Wp 12; WpIl. W /> 22) and a center-tapped secondary winding ( WxI: H si) each with a nachgcordncten Zwciweg rectifier circuit (GI 1. G12: G2I. G22), which work in opposite directions on a trigger circuit (Fig. I). 5. Circuit arrangement according to claim 4, characterized in that the one primary winding (M / Ml) of a differential transformer (DTl) is arranged in a Stroni branch with the bandpass filter (Bp) and the rotor circuit to be monitored (RE, CE) and the other primary winding ( Wp 12) of this transformer (Ο7Ί) together with the one primary winding (M '/> 2I) of the further differential transformer (DTl) forming an auxiliary current circuit in series with the one Widcrslandszweig (resistor Rl) of the resistor arrangement (W) lies, while the other primary winding (WpIl) of the further differential transformer (DTl) is arranged in series with the further resistance Zwcig (resistor R3) of the resistor arrangement (M ') forming a further auxiliary circuit (Fig. I). fi. Circuit arrangement according to Claim 4 or 5. characterized in that the Au3! ov- »ciialtunti a relay (B) with two windings e-.t (Fig. i). 7. Circuit arrangement according to claim 4 or 5, characterized in that the Adsloseschaitung is a resistor iRni) with a downstream current trigger (Si) (Fig. 2). S. Circuit arrangement according to claim 7, characterized in that the current trigger (Si) is preceded by a differential amplifier (Di) ίο (Fig. 2). 9. Circuit arrangement according to one of claims I to 8, characterized in that a choke coil (L3) located in the shunt arm of the bandpass filter (Bp) is so dimensioned. that in connection with a capacitor (Cl ) which is arranged in the series branch of the bandpass filter (Bp) and connected to the rotor circuit (RE. CE) , when an overvoltage occurs in the monitoring circuit, it goes into ferroresonance and thus becomes effective for voltage limitation (Fig. 1). 10. Circuit arrangement according to one of claims I to 9, characterized in that a primary winding (Wpsl. Wpsl) of a protective converter (SW) is arranged in series with the bandpass filter (Bp) in the circuit arrangement and that to the secondary winding (Wss) of the protective converter (SW) a limit value indicator (G) is connected. of the occurrence of ferroresonance the reactor (line 3) at a turning on a current-limiting damping resistor (Rii) into the monitoring circuit causes (Fig. 1). 11. Circuit arrangement according to claim 10. characterized in that the limit value indicator (G) is followed by a protective relay (4, 4). that by opening one of the damping resistance (Rd) normally bridging- 'Kon. aktes (al) switches on the damping resistor (RtI) (Fig. I). 12. Circuit arrangement according to claim II. Characterized in that the protective converter (SIC) in addition to the one primary winding (Wpsl) has a further primary winding (Wpsl) , that both primary windings (Wpsl, Wpsl) are connected to one another at one end and that the common connection point (P5) is connected to the relay contact (al). so that the series circuit consisting of the further primary winding ( Wpsl) and the damping resistor (RcI) is parallel to the relay contact ( a1) (Fig. I). 13. Circuit arrangement according to claim 11 or 12, characterized in that further contacts of the protective relay for switching off the evaluation part (AT) are provided. 14. Circuit arrangement according to one of claims Il to 13, characterized in that Additional contacts of the protective relay (I) for indicating the occurrence of overvoltages Switching on indicator lights are present.