CN202282603U

CN202282603U - Digital thermorelay

Info

Publication number: CN202282603U
Application number: CN2011203478905U
Authority: CN
Inventors: 朱鸽
Original assignee: SUZHOU CHUANGTAI ELECTRONICS CO Ltd
Current assignee: SUZHOU CHUANGTAI ELECTRONICS CO Ltd
Priority date: 2011-09-16
Filing date: 2011-09-16
Publication date: 2012-06-20
Anticipated expiration: 2021-09-16

Abstract

The utility model provides a digital thermorelay, comprising a control module, and a current detection module, an output module, a display module and a key input module which are respectively connected with the control module; and also comprising a power supply module providing electric power for above modules. The digital thermorelay employs the digital technology, has an accurate inverse time lag overload protection characteristic and an reliable open-phase and three phase imbalance protection characteristic, can visually display the working current of a motor to be protected, and is excellent in stability, convenient in operation and accurate in current measurement.

Description

Digital thermal relay

Technical Field

The utility model relates to a protect the thermorelay of motor, especially a digital thermorelay that can show states such as motor overload, lack of phase, unbalanced three-phase.

Background

The known thermal relay at present comprises a bimetallic strip, a guide plate, a lever, a push rod, a switch, a current setting knob, a test key and the like, wherein when a motor is overloaded, the bimetallic strip bends, the bimetallic strip pushes the guide plate, the guide plate pushes the lever, and the push rod on the lever pushes a switch contact to move to a disconnection position, so that the switch is disconnected, and the motor is protected. However, after the thermal relay is used for a period of time, a large error is generated, and the motor cannot be effectively protected because the linear expansion coefficient of the alloy moving plate changes sharply due to the high and low temperature alternate change, particularly due to overcurrent, the temperature of the bimetallic strip rises to the temperature of a phase change point, the alloy moving plate in the bimetallic strip changes phase, namely, the alloy tissue structure and the crystal arrangement change, the size and the distribution of internal stress (thermal stress, mechanical stress and residual stress) of the alloy moving plate change, the change of the internal stress changes physical quantities such as elastic modulus, specific bending and the like of the alloy moving plate, the alloy moving plate generates zero drift, namely, the alloy moving plate cannot recover to an initial state, the position of the guide plate and the lever changes, the position of the push rod finally changes, and the distance between the push rod and the switch contact disconnection position changes; the ordinary thermal relay does not have a function of displaying a distance value and a variation value between a push rod and a switch contact disconnection position, and also has no function of correcting an error. Therefore, the thermal relay with large error and no function can be used for a long time, and a large amount of motors protected by the thermal relay are burnt out.

In order to overcome the defect that the common thermal relay does not have the functions of displaying the distance value and the change value between the push rod and the disconnection position of the switch contact and correcting the error, the digital thermal relay (patent number: 200910104701.9) appearing on the market can display the distance value and the change value of the distance between the push rod and the disconnection position of the switch contact in the shell of the thermal relay, namely the error, and the distance can be adjusted to correct the error, so that the thermal relay which has large error and does not play a role in protection is prevented from being used for a long time, and the aim of effectively protecting the motor is fulfilled. However, such a digital thermal relay is not high enough in accuracy, is too poor in intuitiveness, and cannot clearly display a failure problem or the like.

SUMMERY OF THE UTILITY MODEL

Utility model purpose: an object of the utility model is to provide a high accuracy, high stability, convenient operation, can show motor operating current in real time and carry out effectual digital thermal relay who transships, lacks looks, the unbalanced three phase protection.

The technical scheme is as follows: in order to achieve the above purpose, the utility model adopts the technical proposal that: a digital thermal relay comprises a control module, a current detection module, an output module, a display module, a key input module and a power module, wherein the current detection module, the output module, the display module and the key input module are respectively connected with the control module, and the power module is used for providing power for the modules.

The current detection module comprises a current transformer and an electronic circuit for converting a current signal of the current transformer into a proper voltage signal, and is used for detecting the current value of the motor;

the output module comprises a relay and an electronic circuit for driving the relay, and is used for sending control to the outside;

the display module is electrically connected with the output end of the control module and is used for displaying the current value and the fault information in real time;

the key input module is connected with the input end of the control module and is used for setting the digital thermal relay and the internal parameters by a user;

the control module core is a single chip microcomputer;

the power module converts the voltage provided by the outside into stable low-voltage direct current and provides the required voltage for the whole module.

The three-phase power line of the protected motor passes through the current transformer in the current detection module, the current detection module converts the working current signal of the motor into a proper voltage signal and then sends the proper voltage signal to the singlechip, the singlechip performs A/D conversion on the voltage signal and performs operation to obtain the working current value of the motor, and the working current of the motor is displayed through the display module. The software in the single chip microcomputer realizes accurate overload protection by carrying out inverse time limit integral operation on the detected working current of the motor; reliable open-phase and three-phase unbalance protection is realized by comparing the detected difference of the three-phase currents of the motor. When the abnormal conditions such as overload, open phase, three-phase unbalance and the like are detected, the singlechip drives the output module to disconnect the power supply of the motor.

Through the key input module, a user can conveniently set parameters such as rated current, inverse time limit curve, open-phase action time, three-phase unbalanced action point and the like of a protected motor.

Has the advantages that: due to the adoption of the technical scheme, compared with the prior art, the utility model, have following advantage: by adopting a digital technology, the device has the characteristics of accurate inverse time limit overload protection and reliable open-phase and three-phase unbalance protection; the working current of the protected motor can be visually displayed; good stability, high current detection precision and convenient operation.

Drawings

Fig. 1 is a schematic block diagram of the digital thermal relay according to the present invention;

wherein: 1. a control module; 2. a key input module; 3. a display module; 4. a power supply module; 5. an output module; 6. a current detection module; 61. a transformer; 7. an electric motor.

Detailed Description

Hereinafter, embodiments of the motor stator structure according to the present invention will be further described with reference to the drawings.

The digital thermal relay shown in fig. 1 comprises a control module 1, a key input module 2, a display module 3, a power supply module 4, an output module 5 and a current detection module 6.

Wherein,

the control module 1 mainly comprises a single chip microcomputer and a peripheral circuit thereof, and the single chip microcomputer is programmable, so that the controller is more intelligent.

The input end of the key input module 2 is electrically connected with the control module 1, and a user can set the protection range, the internal parameters and the like of the digital thermal relay through the key input module 2 according to the use requirement.

The display module 3 adopts liquid crystal display or nixie tube display to ensure the display to be clear and visual and is used for displaying the current value, the fault information and the like of the motor in real time.

The power module 4 is used for converting the voltage provided by the outside into stable low-voltage direct current and providing the required voltage for the whole module.

The output module 5 receives the instruction of the control module 1 and sends out control action.

The current detection module 6 is used for detecting the current value of the motor to provide the control module for comparison, judgment and decision.

The specific working process is as follows: the three-phase power line of the protected motor 7 passes through the current transformer 61 in the current detection module 6, the current detection module 6 converts the working current signal of the motor 7 into a proper voltage signal and sends the proper voltage signal to the single chip microcomputer, the single chip microcomputer performs A/D conversion on the voltage signal and performs operation to obtain the working current value of the motor 7, and the working current of the motor 7 is displayed through the display module 3. The software in the single chip microcomputer carries out inverse time limit integral operation on the detected working current of the motor 7 to realize accurate overload protection; reliable open-phase and three-phase unbalance protection is realized by comparing the detected difference of the three-phase currents of the motor 7. When abnormal conditions such as overload, open phase, three-phase imbalance and the like are detected, the singlechip drives the output module 5 to disconnect the power supply of the motor 7.

The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention, so as not to limit the protection scope of the present invention, and all equivalent changes or modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention. The novel protection scope is used.

Claims

1. A digital thermal relay, characterized by:

comprises a control module (1);

the current detection module (6) is connected with one input end of the control module (1) and is used for detecting the current value of the motor, and comprises a current transformer (61) and an electronic circuit for converting a current signal of the current transformer (61) into an appropriate voltage signal;

the output module (5) is connected with one output end of the control module (1) and used for sending control to the outside, and comprises a relay and an electronic circuit used for driving the relay;

the display module (3) is electrically connected with one output end of the control module (1) and is used for displaying the current value and the fault information in real time;

and the key input module (2) is connected with one input end of the control module (1) and is used for setting the digital thermal relay and the internal parameters by a user.

2. The digital thermal relay according to claim 1, wherein: the core of the control module (1) is a singlechip.

3. The digital thermal relay according to claim 1, wherein: an A/D converter is arranged in the control module (1).

4. The digital thermal relay according to claim 1, wherein: the display module (3) adopts liquid crystal display or nixie tube display.

5. The digital thermal relay according to claim 1, wherein: the power supply module (4) converts the voltage provided by the outside into stable low-voltage direct current and provides the required voltage for the whole module.