DE3111400C2 - Device for phase difference protection of electric motors - Google Patents

Abstract

The device for phase difference protection of electric motors contains series-connected current transformer units (21, 29, 28), the number of which depends on the required degree of security of the device. The secondary windings (9, 10, 11, 12, 13, 14) of the current transformers (1, 2, 3, 4, 5, 6) are connected to the first and the last current transformer unit, the primary windings of which pass through the busbars (7) of the electric motor (8) can be formed. Phase comparison units (78, 79 and 80) are connected to the current transformer units (21, 29, 28) and are electrically connected to a disconnection block (81) provided for disconnecting the electric motor.

Description

The invention relates to devices for phase difference protection of electric motors.

The device implemented according to the invention can have been successfully used to protect high power electric motors from phase short circuits.

With continuously increasing individual performance of electric motors, there is a significant increase in reliability the facilities for their protection against short circuits, e.g. B. of devices for phase difference protection of the electric motors required, including the control of these facilities during their operation becomes necessary.

A known device for phase difference protection of electric motors within the scope of the preamble of claim 1 according to the Soviet copyright certificate 5 99 309 contains current transformers, their Primary windings are each formed by a busbar of the electric motor, a main current converter unit whose inputs are connected to a terminal of secondary windings of the current transformers are a main phase comparison unit, the inputs of which are connected to the current transformer unit are a source of food that comes with. the power converter unit and the phase comparison unit are electrically connected

and a shutdown block provided for shutting down the electric motor, which is connected to the phase comparison unit and the supply source is electrically connected

The device, however, has a low reliability because of failure due to breakdown or circuit interruptions in one of the structural units fails or responds incorrectly, whereby the The electric motor is damaged or switched off unnecessarily.

To detect errors, the device must be put out of operation, including the electric motor must be switched off.

The invention is based on the object of a device for phase difference protection of electric motors to develop their structural units increasing the reliability of the device and their enable continuous operational control.

In the case of the facility mentioned at the beginning, this task is carried out by the features in the identifier of the Claim 1 solved

It is useful in the device for phase difference protection of electric motors the additional installation of electrically connected to the supply source and to provide certain control units for monitoring the operation of the facility, their number the total number of CT units, including the main CT unit and additional CT units, should correspond, the input of each control unit to the corresponding phase comparison unit and their output is connected to the corresponding input of the shutdown block.

Each control unit is advantageously connected in series a relay, a resistor and a signal lamp

The relay of the control unit is expediently designed with two windings, one of which Connections are interconnected and connected to the power source. You are in line with two lying contact pairs provided, of which the common connection point to the resistance of the Control unit is switched and a contact is connected to the other terminal of one of the windings is, and the relay is equipped with two diodes, the anodes of which contact the other be switched, with the cathode of a diode connected to the other terminal of the working winding will.

If the device for phase difference protection of electric motors with two additional current transformer units is provided, it is useful to have three electrically interconnected in the shutdown block Relays and thyristors to be provided according to the number of relays, the anode of each thyristor with the Terminal of the corresponding relay is connected, and resistors according to the number of relays to be installed, one connection of each resistor to the control electrode of the corresponding thyristor is connected.

The electrical connection between the relays should be established via contacts of all three relays will.

A contact of the first relay is to be connected to a contact of the second relay, whose second contact is connected to a contact of the third relay and in which to switch off the A diode is to be provided in which the anode is connected to the connection

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point of the contacts of the first and the second relay and the cathode to the connection point of the Contacts of the second and third relay can be connected.

The invention gives the possibility of the operating state of the device in the event of malfunctions in one to preserve their structural units and thus exclude failures or incorrect response of the device, their Increase reliability and ensure continuous operation of the electric motor.

The invention also enables continuous control of the operation of the device and the Signaling of the resulting errors as well as error elimination during operation. This contributes further to increase the reliability of the device and ensures trouble-free operation of the Electric motor.

The invention will now be based on exemplary embodiments explained in more detail with reference to the drawings It shows

F i g. 1 is a block diagram of the device for Phase difference protection according to the invention;

F i g. 2 shows a block diagram of the device for phase difference protection according to FIG. 1 with control units for monitoring the operation of the device according to the invention;

F i g. 3 shows a basic circuit diagram of the current transformer units and the phase comparison units according to FIG Invention;

Fig. 4 shows a functional diagram of the control unit for monitoring the operation of the device according to FIG Invention;

Fi g. 5 a schematic diagram of the in the control unit built-in relay according to the invention;

6 shows a functional circuit diagram of the shutdown block constructed according to the invention for shutting down the electric motor;

F i g. 7 shows a basic diagram of the electrical connection the relay built into the switch-off block according to the invention.

A device for phase difference protection of electric motors is described below as an exemplary embodiment considered, in order to ensure the required level of security, two additional CT units are used.

The device for phase difference protection of electric motors contains current transformers 1,2,3,4, 5, 6 (FIG. 1), the primary windings of which are formed by busbars 7 of an electric motor 8. At one of the connections of the secondary windings 9, 10, 11, 12,13,14 of the transformers 1,2,3,4,5 and 6 are the Inputs 15, 16, 17, 18, 19 and 20 of the main current converter unit 21 connected, and to the other connections of the secondary windings 9, 10, 11, 12, 13, 14 are the outputs 22, 23, 24, 25, 26, 27 of the additional current transformer unit 28. With the main current transformer unit 21 are the inputs 30,31,32,33, 34, 35 of the additional current converter unit 29 are connected. To the current converter unit 29 are the Inputs 36, 37, 38, 39, 40, 41 of the additional current transformer unit 28 connected. With the current transformer units 21, 29, 28 are all inputs 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, the inputs 54, 55, 56, 57,58,59, 60, 61,62, 63, 64,65 or the inputs 66, 67 , 68,69,70,71,72,73,74, 75,76,77 of the phase comparison units 78, 79 and 80 connected. The shutdown block 81 is connected to the phase comparison units 78, 79, 80 its inputs 82, 83 and 84 are switched. To the

Inputs 85, 86, 87 of Stromwandiereinheiten 21, 29 and 28 is the positive pole of the supply source 88. To the Inputs 89, 90, 91 of the phase comparison units 78, 79 and 80, respectively, are the negative pole of the supply source 88 connected. The inputs 92, 93 of the shutdown block 81 are connected to the negative or positive pole of the supply source 88 connected. The switch-off block 81 is connected to the input 94 of a switch 95, which is on which acts as the primary windings of the transformers 4, 5, 6 busbars 7 is connected.

The other variant of the device for phase difference protection of electric motors contains for the purpose of their operational control control units 96,97, 98 (Fig. 2), the inputs 99, 100 and 101 to the Phase comparison units 78, 79 and 80 are connected. The inputs 102, 103, 104 of the control units 96, 97 and 98 are connected to the negative pole of the supply source 88. The inputs 82 S3 84 of the peel-off block 8! are with the control units 96, 97 and 98 are connected.

Each current converter unit 21, 29, 28 contains transformers 105, 106, 107, 108, 109, 110 (Fig. 3) with primary windings Ul, 112, 113, 114, 115 or 116. Between the terminals of each secondary winding 117, 118, 119, 120, 121, 122 of the transformers 105, 106, 107, 108, 109 and 110, respectively, are resistors 124 and 125, 126 and 127, 128 connected at point 123 and 129, 130 and 131, 132 and 133, 134 and 135. Between resistors 124 and 127, 128 and 131, 132 and 135 are resistors 136, 137 and connected, respectively. Between resistors 125 and 126, 129 and 130, 130 and 134 are resistors 139, 140 and 141, respectively. Each phase comparison unit 78, 79, 80 contains diodes 142, 143, 144, 145, 146, 147, the cathodes of which are interconnected at junction 148 are and at their anodes the one terminals of the resistors 149, 150, 151, 152, 153 and 154 in the Connection points 155, 156, 157, 158, 159 and 160 are switched. The other connections of the resistors 149, 150, 151, 152, 153, 154 are interconnected at point 161. At the connection points 155, 156, 157, 158, 159, 160 are the anodes of diodes 162 and 163, 164 and 165, 166 and 167, 168 and 169, 170 and 171 or 172 and 173 connected.

Each control unit 96, 97, 98 contains one of one Relay 174 (Fig. 4), a resistor 175 and a signal lamp 176 existing series network.

The relay 174 has two windings 177 and 178 (Fig. 5), one of which connects terminals together and are connected to the Minsupol of the supply source 88. A: n other connection of the winding like this 178 is a contact pair 179, which with another contact pair 180 at the connection point 181 in Is connected in series. With the other connection of the winding 177, the cathode of a diode 182 is at the point 183 connected. At the connection point 184, the anode of a further diode is connected to the anode of the diode 182 185 and the pair of contacts 180 connected.

The block 81 provided for switching off the electric motor contains three together at point 186 (FIG. 6) associated Reiais 187,188,189, with which the anodes of thyristors 190 are connected, the cathodes of which are interconnected at connection point 191 and connected to the Negative pole of the feed source 88 are connected. At the control electrode of each thyristor 190 is a Resistor 19Z A contact 193 is connected to connection point 186.

The relays 187, 188, 189 contain windings 194, 195 and 196 (FIG. 7), each with a connection in the Point t86 are interconnected. The relay 187 has a pair of contacts 197 to which relay 188 belongs Contact pairs 198, 199 and a contact pair 200 for relay 189.

The contact pairs 197 and 198 are connected to one another at point 201. Located at connection point 201 the anode of a diode 202, the cathode of which is connected to the contact pairs 199 and 200 at point 203 is.

The device for phase difference protection of electric motors works as follows.

The transformers 1, 2, 3, 4, 5, 6 (Fig. 1) deliver to the inputs 15, 16, 17, 18, 19, 20 of the current transformer unit 21 a signal. From the outputs of this unit 21 the signals reach the inputs 30,31,32,33,34, 35 of the current transformer unit 29 and from this to the inputs 36,37,38,39,40,41 of the current transformer unit 28.! N the Sf.romwanrllereinhrilrn 21. 29. 28 the Signals are transformed and then arrive at the phase comparison units 78, 79, 80. in which they are processed. The supply source gives signals to the inputs 85, 86, 87, 89, 90, 91 and 92, 93 of the units 21,29,28, 78,79,80 or the shutdown block 81.

From each phase comparison unit 78, 79, 80 that Signal to the shutdown block 81 at the time the short circuit occurs in the electric motor 8 or between his' * busbars 7 as well as breakthroughs or interruptions in the components of the Building units 21, 78, 29, 79, 28.80 delivered. A signal to turn off the switch 95 is received from block 81 at the arrival of signals at any two inputs, e.g. B. at inputs 82, 83 or all three Inputs 82,83,84 delivered.

To control the operation of the facility in the Cases of the mentioned short circuits and errors supply the phase comparison units 78, 79, 80 signals to the Control units 96, 97, 98 (Fig.2), in turn Send signals to inputs 82, 83, 84 of block 81. The facility continues to operate as above described.

The operating personnel receives light signals from the control units 96, 97, 98 that indicate the operating status the institution.

The operation of the current transformer units 21,29,28 and of the phase comparison units 78, 79, 80 is shown below using the example of the interaction of Units 21 and 78 considered.

During load operation and when the electric motor 8 is idling, the secondary windings 9 and 12, 10 and 13, 11 and 14 of transformers 1 and 4.2 and id 5 or 3 and 6 via inputs 15 and 16, 17 and 18, 19 and 20 of the current transformer unit 21 the transformers 105 and 106, 107 and 108, 109 and UO (Fig. 3) Signals are supplied that follow the industrial frequency in phase in each half cycle, because the currents, the rails 7 acting as the primary windings of the transformers 1 and 4, 2 and 5, 3 and 6 (Fig. 1, 2) flow, are in phase. At the arrival of signals to the primary winding boys 111, 112, 113, 114, 115, 116 (Fig.3) of the transformers 105, 106, 107,108,109 or 110 during the negative half-wave this current is generated by the secondary windings 117,118,119,120,121,122 of these transformers the corresponding inputs of the phase comparison unit 78 given negative-going signals. Consequently the diodes 170, 173, 166, 169, 162, 165 of the assembly 78 are opened, with the input 99 of the Control unit 96 the signals are missing because the current of the

Supply source 88 through resistors 149, 150, 151, 152, 153, 154, through the diodes 170, 173, 166, 169, 162, 165 and through the resistors 124, 126,128,130,132, 134 and the connection point 123 flows.

If errors occur in the facility, e.g. B. if any diode 170, 172, 173, 171, 166, 168, 169, 167, 162, 164, 163, 165 of the phase comparison unit 78 is broken, supplies the latter to the input 99 from the control unit 96 a signal. This is due to the fact that the winding 117 is damaged, for example the diode 170 or 171 is connected to the diode 145.

When any diode 142, 143, 144, 145, 146, 147 of the phase comparison unit 78 breaks down a signal is also given on input 99 of the control unit%.

In the event of a break in any resistor 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, e.g. B. in resistance 124,> becomes from the phase comparison! - means 78 during the positive current half-wave of the industrial frequency and when the diode 171 is blocked the resistor 153 and the diode 146 output a signal to the input 99 of the control unit 96.

In the event of a conductor interruption in any secondary winding 117, 118, 119, 120, 121, 122, e.g. in winding 117, when the electric motor 8 (Figs. 1, 2) is started, the phase comparison unit 78 reaches the input 99 of the control unit% a signal because the diode 170 (Figure 3) as a result of the signal arrival from the winding 118 via the resistors 139, 125, 124 gif ^; is blocked at the same time with the diode 171.

The control units 96, 97, 98 provided for monitoring the operation of the facility (Fig. I. 2) work like this.

Upon arrival of a positive signal e.g. B. at the input 99 of the control unit 96, the winding 177 (Fig. 4, 5) of the relay 174 with current flowing through it, the contact pair 180 of this relay is closed and the signals via the diode 185 dem Disconnection block 81 and the winding 177 of the relay 174 via the diode 182.

When a negative signal arrives, the pair of contacts 179 is closed, and the signal is sent to the Winding 177 of relay 174 is applied.

The control units 97, 98 function in a similar manner.

The shutdown block 81 (FIGS. 1, 2) intended to switch off the electric motor operates as follows.

When signals appear at inputs 82,

83, 84 of the disconnection block 81 are the thyristors 190 (Fig. 6) conductive, the signal being applied to windings 194,

ίο 195,196 (Fig. 7) of the relays 187,188 and 189 respectively will.

In the relays 187, 188, 189 the contact pairs 197, 198 and 199 or 200 are closed.

In the event of short circuits inside the electric motor 8 (Fig. 1, 2) or between its busbars 7, z. B. between the busbars 7, which are used as primary windings of the transformers 4 and 5, the currents flow in the as primary windings of the

~ T - (- nni.fnf * mntm.An I r * ri Λ ιιιίρίηηΊηη C ** K »Λ *» * »*» 1 in

iiuiMti / iiiiutuit.11 ■ uiiu -ν niinbiiubii k / t, iii «.ii« »ii ι in antiphase. As a result, the signals appear at the inputs 15 and 16, 30 and 31, 36 and 37 of the current transformer units 21, 29 and 28 also in antiphase, with the diodes 170 and 171 or 172 and 173 (FIG. 3) of the phase comparison units 78, 79, 80 are blocked. Therefore, the signals reach the inputs 99, 100 and 101 of the control units 96, 97 and 98 via the resistors 153, the diode 146, the resistor 154 and the diode 147. The device continues to operate as above

JO described.

In the case of other phase short circuits, the signals are sent to the control units 96, 97 and 98 via the Resistors 149,150,151,152 and across the diodes 142, 143,144,145 supplied.

J5 The invention enables the exchange of faulty structural units of the device without affecting the operation of the device itself or the Electric motor is interrupted.

The invention also makes it possible to meet the requirements for the qualification of the operating staff and reduce the number of operators.

In addition 6 sheets of drawings

Claims (7)

Patent claims: 1. Device for phase difference protection of electric motors, which contains current transformers in which the primary winding of each transformer is formed by a busbar of the electric motor, and which has a main current transformer unit, the inputs of which are connected to a terminal of the secondary windings of the current transformers, as well as a main Has phase comparison unit, the inputs of which are connected to the current converter unit, and contains a supply source electrically connected to the current converter unit and the phase comparison unit and a shutdown block for switching off the electric motor when a phase difference occurs, which is electrically connected to the phase comparison unit and to the supply source, characterized by the Equipped with an even number of additional current transformer units (28, 29) connected in series with one another and electrically connected to the supply source (88), the number of which depends on the required Si depends on the degree of security of the device, the inputs (30, 31, 32, 33, 34, 35) of one of the additional current transformer units (28, 29) being connected to the main current transformer unit (21), and the outputs of the latter to the other connections of the secondary windings (9, 10, 11, 12, 13, 14) of the current transformers (1, 2, 3, 4, 5, 6) jo are connected, as well as through the installation of additional phase comparison units (79, 80) corresponding to the number of zusätzftVien current transformer units (28, 29), wherein a group of inputs (90, 91) of the additional Phasenver- a same units (79, 80) is connected to the supply source (88), the other inputs (54, 55, 56, 57 58,59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77) with the additional current transformer units (29, 28) and the outputs are connected to the inputs (82, 83, 84) of the shutdown block (81). 2. Device according to claim 1, characterized by the additional installation of with the Supply source (88) electrically connected and intended for monitoring the operation of the device Control units (96, 97, 98), the number of which is the total number of CT units, including The main current transformer unit (21) and additional current transformer units (28, 29), wherein the input (99, 100, 101) of each control unit (96, 97, 98) to the corresponding one Phase comparison unit (78, 79, 80) and the output to the corresponding input (82,83,84) of the shut-off block (81) are connected. 3. Device according to claim 2, characterized in that the monitoring of the operation of the Device provided control unit (96,97,98) as a series connection of a relay (174), one Resistance (175) and a signal lamp (176) is constructed. 4. Device according to claim 3, characterized in that the relay (174) of the control unit (96, 97, 98) is designed with two windings (177, 178), one of which has connections are interconnected and connected to the supply source (88), and with two in series lying contact pairs (179, 180), of which the common connection point (181) is connected to the resistor (175) of the control unit (96, 97, 98) and one contact with the other Connection of a winding (178) is connected, and the relay (174) with two diodes (182, 185) is equipped, of which the anodes are connected to the other contact (180) while the cathode of one diode is connected to the other terminal of the other winding (177) 5. Device according to one of claims 1 to 4, characterized in that the shutdown block (81) if the device is designed with two additional current transformer units (28, 29), three electrically interconnected relays (187, 188, 189) and thyristors (190) according to the Number of relays (187, 188,189), the anode of each thyristor (190) with the connection of the corresponding relay (187,188,189) is connected, and resistors (192) corresponding to the number of relays (187,188,189), and one terminal each Resistor (192) is connected to the control electrode of the corresponding thyristor (190). 6. Device according to claim 5, characterized in that the electrical connection between the relays (187, 188, 189) via contacts (197, 198, 199,200) of all three relay relays (187,188,189). 7. Device according to claim 6, characterized in that a contact (197) of the first relay (187) with a contact (198) of the second relay (188) is connected, its second contact (199) on a contact (200) of the third relay (189) is connected, and that in which to switch off of the electric motor certain shutdown block (81) a diode (202) is additionally provided in which the anode to the junction (201) of the contacts (197, 198) of the first and the second Relay (187, 188) and the cathode to the connection point (203) of the contexts (199,200) of the second and third relays (188,189) are connected.