SU1359845A1 - Device for protecting single-phase induction electric motor against current overload - Google Patents

Abstract

The invention relates to electrical engineering and can be used to protect a single-phase asynchronous motor against overload in two modes, for example, in starting and operating modes. The aim of the invention of jpr ' - rt is to increase the reliability and sensitivity of protection of a single-phase asynchronous motor in start-up and operating modes. At the time of starting the motor 9 ,. which starts by closing the contacts 5, 12, 13 of the driver and the power contacts I, 2 magnetic starters, thermoelement, IIdifferential of three-pole thermal relay is shunted by contact 1 2 and then switched on by contact 13 in series with thermoelement 10. Asynchronous electric motor is protected with thermoelectric elements, which are attached, which are attached by thermoelement 10. Asynchronous electric motor is protected by thermoelements 8 and 10, which are attached by the thermocouple 10. the currents flowing through it and the mechanical overload on the differential rail, the opening contact Zv of the magnetic starter circuit and the motor disconnection. Starting mode Corresponds to the part of the amp-second characteristic 2 Il. 6 € (L with JV CO 00 ate w tDUl-l

Description

The invention relates to electrical engineering and can be used to protect a single-phase asynchronous motor overload in two modes, for example, starting and working.

The aim of the invention is to increase the reliability and sensitivity of the search for a single-phase asynchronous motor in the starting and operating modes.

Figure 1 shows a diagram of the device for protection of a single-phase asynchronous motor against overload in start-up and operating modes; FIG. 2 shows the ampere-second characteristics of a three-pole thermal differential relay with three-pole and two-pole modes of operation.

The device contains a magnetic starter with power contacts 1 and. 2, connected to the power supply circuit of the electric motor, and a three-pole thermal differential relay, pin 3 of which is connected in series with the magnetic actuator 4, button 5 Start, which is bridged by the magnetic start contact terminal and the button 7 Stop, Sun chain is connected between the wires of the mains, the first thermoelement 8 of the thermal three-pole differential relay is connected to the first power contact I of the magnetic starter and the first output of the working winding of the electric motor 9, the second thermoelement 10 ope The second relay is connected to the second power contact 2 of the magnetic starter, and its second output to the first output of the third thermoelement 11 of the thermal relay and through the second closing 12 and disconnecting 13 contacts of the driver, made in the form of a multi-contact Start button, is connected to the second the output of the third thermoelement of the above relay, the common point of these contacts is connected to the second output of the winding winding of the electric motor 9, and through the first closing contact 14 of the driver and the phase shifting element 15 to the starting winding e motor 9.

Organ can be manual

or automatic. As a manual-55 potential release, as the station can use the principle of operation of the thermal release or universal switch. In the lei is similar to the action of thermal reclamation of the automatic defining member

time, voltage, current, having appropriate contact pairs.

The device works as follows.

For the time of starting the electric motor 9, which starts by closing the contacts 5, 12 and 14 of the driver and power contacts I and 2 of the magnetic starter, the thermoelement 11 of the differential three-pole thermal relay is shunted by the contacts 12 and then is switched on by the contacts 13 of the driver in sequence with the thermal element 10. Asynchronous the electric motor is protected by thermoelements 8 and 10 as during start-up, which are heated by the currents flowing through them and, when overloaded, mechanically act on

differential rail, release contact 3 in the coil circuit of the magnetic starter and disconnecting the engine. The start mode corresponds to the canopy part of the ampere-second characteristic 2

(figure 2).

In the load mode, an asynchronous motor is protected by thermocouples 8, 10, and 11, which are heated by the same currents and, if a given current is exceeded, turn off the motor. The load mode corresponds to the upstream part of the ampere second characteristic 1 (Fig. 2).

Triggered differential

relays at the same currents in all

three thermoelements occur as a result of greater heating of bimetallic plates than with the same currents and heating of a part of thermoelements

,relay.

The relay is returned to working condition in the usual way for thermal relays - self return or manual reset. Under normal conditions

starting the engine bypassing (disconnecting) and turning on part of the thermoelement into the network is carried out by the body defining the operation mode of the engine.

A device for protection of a single-phase asynchronous motor against overload in start-up and operating modes can also be implemented on the basis of a circuit breaker with a diffuser, but has a lower accuracy of operation.

In many cases (for small and medium power engines) it is sufficient to shunt one or two thermoelements with force contacts. Of the target organ, since the resistance of each thermoelement is much greater than the resistance of the shunt contact.

The use of the proposed protection device of a single-phase asynchronous motor in comparison with the known one provides high-quality reliable protection of the motor and starting element, increases the degree of unification of three-phase and single-phase asynchronous electric drives, reduces the number of protection and control devices;

Claims (1)

Formula invented and. A device for protection of a single-phase asynchronous electric motor against current overload, containing a magnetic starter with power contacts for connecting an electric motor to the supply wires, a thermal relay, the contact of which is connected in series with the magnetic starter coil, the Start button, is blocked by a block contact of the magnetic starter, and the Stop button, the entire chain is provided with leads for connection between the wires of the Lens network, while the first thermal element of the thermal relay is equipped with leads for Connections are sequentially connected to the first power contact of the magnetic starter and the first output of the motor winding, the second thermal element of the thermal relay is equipped with terminals, one of which is connected to the second power contact of the magnetic starter, and the driver, the first closing contact of which is connected to one output of the phase-shifting element The second terminal of which is intended to be connected to the output of the starting winding of the electric motor, characterized in that, in order to increase reliability and increase the sensitivity of the In the starting and operating modes, the mentioned thermal relay is made in the form of a thermal three-pole differential relay, the second output of the second thermoelement of the thermal relay is connected to the first output of the third thermoelement of the thermal relay and through the input of the second closing element, made in the form of a multi-contact button, connected to the second output of the third thermoelement of the thermal relay, and the common point of these contacts of the setting body serves to connect to the second output of the working volume weave electric .trodvigatel. L 0.5 O.V 1 1.1252 b f 56 8 70 ZO / l-. FIG. 2 Editor L.Povkhan Compiled by V. Orlov Tehred M. Didyk Order 6159/53 Circulation 618 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab, 4/5 Production and printing company, Uzhgorod, st. Project, 4 Proofreader A.Ilyin