GB2089151A

GB2089151A - Circuit arrangement for an a.c. motor with an electromagnetically releasable spring-loaded brake

Info

Publication number: GB2089151A
Application number: GB8133983A
Authority: GB
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1980-11-28
Filing date: 1981-11-11
Publication date: 1982-06-16
Also published as: JPS57113781A; DE3045027A1; DE3045027C2; GB2089151B

Abstract

The exciter winding of the electromagnet of the spring-loaded brake is divided into two winding halves (7 and 8), which are connected commonly at one winding end to the mains side end of a phase winding (3) of the motor and at their other winding end are connected separately via opposite-poled diodes (9 and 10) to one phase (T) of the alternating current network feeding the motor. In order to achieve a direct-current sided interruption of the exciter circuit of the magnet, it is proposed that one diode (10) on the mains side and the other diode (9) on the motor side of a switching contact (6) in the connecting line of the motor be connected to the corresponding mains phase (T). <IMAGE>

Description

SPECIFICATION Electrical circuit arrangement for an alternating current motor with an electromagnetically releasable spring-loaded brake This invention relates to an electrical circuit arrange mentor an alternating current motor with an electromagnetically releasable spring-loaded brake, in which the exciter winding of the magnet is divided into two winding halves, which are commonly connected at their one winding end to the mains supply end of a phase winding of the motor and which are connected at their other winding end in each case via a diode to a phase of the alternating current supply feeding the motor. A circuit arrangement of this type is known from DE-OS 22 59349.

Adjusting drives, particularly regulating drives, which operate with braking motors, call for short times for the brake to come into operation and release. Short enough release times for the brake are achieved by rapid excitement. In order to obtain short enough times for the brake to take effect, it must be switched off on the direct current side.

The present invention has been developed primarily, though not exclusively, with a view to provide a circuit arrangement whereby a direct-current-sided interruption of the exciter circuit of the magnet serving to release the brake is possible.

According to the invention there is provided electrical circuit arrangement for an alternating current motor with an electromagnetically releasable spring-loaded brake having an exciter winding of the electromagnet divided into two winding halves, which are connected commonly at one end to the mains-supply end of a phase winding of the motor and at each of their other winding ends via respective opposite-poled diodes to one phase of the alternating current network feeding the motor, in which one diode on the mains side, and the other diode on the motor side of a switching contact in the connecting line of the motor are connected to the corresponding mains phase.

The circuit arrangement has the advantage that no additional switching contact is required for the direct-current-sided interruption of the exciter circuit. Thus, even the diodes of already existing installations can still be connected in the specified manner and therefore the advantages of the circuit arrangement can be used for these existing installations.

One diode may be connected to the mains side of the switching contact via an auxiliary contact operating synchronously with the switching contact in the connecting line, so that the exciter winding is potentially separated from the mains at the same time as the motor is switched-off.

One embodiment of circuit arrangement according to the invention will now be described in detail, by way of example only, with reference to the accompanying circuit diagram.

Indicated with 1 to 3 are the three phase windings of a motor, which can be connected to the phases R, S, T of an alternating current supply via switching contacts 4 to 6. The phase windings 1 and 2 are hereby connected directly to the corresponding phases R and S via the switching cotacts 4 and 5. On the other hand, the exciter winding of an electromagnet used to release a spring-loaded brake is in series with the phase winding 3. This exciter winding consists of two winding halves 7 and 8, which are commonly connected by one winding terminal to the mains-side end of the phase winding 3. The other end of winding of each of the winding halves 7 and 8 is connected to diodes 9 and 10 respectively. The diodes 9 and 10 are connected with opposite poles to the winding ends of the winding halves 7 and 8.Of the two diodes 9 and 10, diode 9 is connected on the motor side of the switching contact 6 to the mains phase T, and diode 10, on the other hand, is connected to the mains side of the switching contact 6.

A further variation of the circuit is shown by a dotted line, whereby the line connected tio the diode 10 is connected to the mains phase T via an auxiliary contact 11 on the mains side of the switching contact 6. As also shown by a dotted line, the auxiliary contact 11 is mechanically coupled to the switching contact 4 to 6, so that it connects synchronously with these.

The circuit arrangement operates as follows: By closing the switching contacts 4 to 6, voltage is applied to both the phase windings 1 to 3 of the motor and the two winding halves 7 and 8. Therefore, the high initial motor current flows through the two winding halves 7 and 8. As a result of this high current, quick reaction of the electromagnet is effected and therefore a correspondingly rapid release of the spring-loaded brake. If the motor is switched-off by opening the switching contacts 4 to 6, then the exciter circuit of the electromagnet is interrupted simultaneously by the switching contact 6 and therefore rapid de-excitation of the magnet is achieved, so that the brake begins to function in the shortest possible time under the action of its springloading.

Since the electromagnet used to release the brake is built on to the motor, the connection, on the motor side, of the diode 9 can be constructed directly in the terminal box of the motor. A separate line is necessary only for the other diode 10 to be connected to the mains side of the switching contact 6.

Since, in practice, the switching devices and motors are usually arranged at great distances apart, the described circuit arrangement brings about considerable saving in respect of connecting lines.

With this circuit arrangement, there is also no unbalanced network for the motor, since both the lines leading from the phase windings 1 and 2 to the switching contacts 4 and 5 and the lines leading from the diodes 9 and 10 to the switching contact 6 are of the same length, and current only passes through these two lines connected to the diodes 9 and 10 alternatively for one half-wave in each case.

1. Electrical circuit arrangement for an alternating current motor with an electromagnetically releasable spring-loaded brake having an exciter wind

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Electrical circuit arrangement for an alternating current motor with an electromagnetically releasable spring-loaded brake This invention relates to an electrical circuit arrange mentor an alternating current motor with an electromagnetically releasable spring-loaded brake, in which the exciter winding of the magnet is divided into two winding halves, which are commonly connected at their one winding end to the mains supply end of a phase winding of the motor and which are connected at their other winding end in each case via a diode to a phase of the alternating current supply feeding the motor. A circuit arrangement of this type is known from DE-OS 22 59349. Adjusting drives, particularly regulating drives, which operate with braking motors, call for short times for the brake to come into operation and release. Short enough release times for the brake are achieved by rapid excitement. In order to obtain short enough times for the brake to take effect, it must be switched off on the direct current side. The present invention has been developed primarily, though not exclusively, with a view to provide a circuit arrangement whereby a direct-current-sided interruption of the exciter circuit of the magnet serving to release the brake is possible. According to the invention there is provided electrical circuit arrangement for an alternating current motor with an electromagnetically releasable spring-loaded brake having an exciter winding of the electromagnet divided into two winding halves, which are connected commonly at one end to the mains-supply end of a phase winding of the motor and at each of their other winding ends via respective opposite-poled diodes to one phase of the alternating current network feeding the motor, in which one diode on the mains side, and the other diode on the motor side of a switching contact in the connecting line of the motor are connected to the corresponding mains phase. The circuit arrangement has the advantage that no additional switching contact is required for the direct-current-sided interruption of the exciter circuit. Thus, even the diodes of already existing installations can still be connected in the specified manner and therefore the advantages of the circuit arrangement can be used for these existing installations. One diode may be connected to the mains side of the switching contact via an auxiliary contact operating synchronously with the switching contact in the connecting line, so that the exciter winding is potentially separated from the mains at the same time as the motor is switched-off. One embodiment of circuit arrangement according to the invention will now be described in detail, by way of example only, with reference to the accompanying circuit diagram. Indicated with 1 to 3 are the three phase windings of a motor, which can be connected to the phases R, S, T of an alternating current supply via switching contacts 4 to 6. The phase windings 1 and 2 are hereby connected directly to the corresponding phases R and S via the switching cotacts 4 and 5. On the other hand, the exciter winding of an electromagnet used to release a spring-loaded brake is in series with the phase winding 3. This exciter winding consists of two winding halves 7 and 8, which are commonly connected by one winding terminal to the mains-side end of the phase winding 3. The other end of winding of each of the winding halves 7 and 8 is connected to diodes 9 and 10 respectively. The diodes 9 and 10 are connected with opposite poles to the winding ends of the winding halves 7 and 8.Of the two diodes 9 and 10, diode 9 is connected on the motor side of the switching contact 6 to the mains phase T, and diode 10, on the other hand, is connected to the mains side of the switching contact 6. A further variation of the circuit is shown by a dotted line, whereby the line connected tio the diode 10 is connected to the mains phase T via an auxiliary contact 11 on the mains side of the switching contact 6. As also shown by a dotted line, the auxiliary contact 11 is mechanically coupled to the switching contact 4 to 6, so that it connects synchronously with these. The circuit arrangement operates as follows: By closing the switching contacts 4 to 6, voltage is applied to both the phase windings 1 to 3 of the motor and the two winding halves 7 and 8. Therefore, the high initial motor current flows through the two winding halves 7 and 8. As a result of this high current, quick reaction of the electromagnet is effected and therefore a correspondingly rapid release of the spring-loaded brake. If the motor is switched-off by opening the switching contacts 4 to 6, then the exciter circuit of the electromagnet is interrupted simultaneously by the switching contact 6 and therefore rapid de-excitation of the magnet is achieved, so that the brake begins to function in the shortest possible time under the action of its springloading. Since the electromagnet used to release the brake is built on to the motor, the connection, on the motor side, of the diode 9 can be constructed directly in the terminal box of the motor. A separate line is necessary only for the other diode 10 to be connected to the mains side of the switching contact 6. Since, in practice, the switching devices and motors are usually arranged at great distances apart, the described circuit arrangement brings about considerable saving in respect of connecting lines. With this circuit arrangement, there is also no unbalanced network for the motor, since both the lines leading from the phase windings 1 and 2 to the switching contacts 4 and 5 and the lines leading from the diodes 9 and 10 to the switching contact 6 are of the same length, and current only passes through these two lines connected to the diodes 9 and 10 alternatively for one half-wave in each case. CLAIMS

1. Electrical circuit arrangement for an alternating current motor with an electromagnetically releasable spring-loaded brake having an exciter wind ing of the electromagnet devided into two winding halves, which are connected commonly at one end to the mains-supply end of a phase winding of the motor and at each of their other winding ends via respective opposite-poled diodes to one phase of the alternating current network feeding the motor, in which one diode on the mains side, and the other diode on the motor side of a switching contact in the connecting line of the motor are connected to the corresponding mains phase.

2. Electrical circuit arrangement according to claim 1, in which said one diode is connectible to the mains side of the switching contact via auxiliary contact operable synchronously with the switching contact in the connecting line.

3. Electrical circuit arrangement according to claim 1 and substantially as hereinbefore described with reference to, and as shown in the accompany ing drawing.