CN204730951U - A kind of transformer overtemperature alarm - Google Patents

Abstract

The utility model provides a kind of transformer overtemperature alarm, comprise temperature sense circuit, and driving warning circuit, described alarm comprises comparer and preset potential circuit, and described comparer is by the current potential of reduced temperature sensor circuit and preset potential thus drive warning circuit to report to the police.Comparer is adopted to carry out design comparison circuit, only need to arrange a preset potential to compare with the partial pressure potential of thermistor, overtemperature alarm can be realized export, and drive alarming horn work, circuit is simple and easy to realize, and not needing, control chip is set and carries out detection driving, cost savings.

Description

A Transformer Over-Temperature Alarm

technical field

The utility model relates to the field of transformer application technology, in particular to a transformer over-temperature alarm.

Background technique

The transformer is a common electrical component, and because it is accompanied by changes in voltage and current during its operation, which is equivalent to a change in energy, heat is inevitably generated during the operation of the transformer. The heat will have a great impact on the performance of the voltage transformer, so in the prior art, the cooling of the transformer will be considered. According to the cooling method, existing transformers can be divided into: dry-type transformers, which rely on air convection for natural cooling or fan cooling, and are mostly used for small-capacity transformers such as high-rise buildings, high-speed toll stations, local lighting, and electronic circuits; oil-immersed transformers , Rely on oil as the cooling medium, such as oil-immersed self-cooling, oil-immersed air-cooled, oil-immersed water-cooled, forced oil circulation, etc.

Although the above two cooling methods can relieve the heat generated by the transformer to a certain extent, due to the continuation of the working time of the transformer, no matter which cooling method can completely dissipate the generated heat, resulting in continuous accumulation of heat, it will Cause the transformer to overheat, resulting in machine or equipment failure.

In the prior art, to deal with over-temperature, the control chip is generally used to collect the temperature, so as to drive the alarm. Although the problem can be solved well, this method is costly and the design is relatively complicated.

Utility model content

The technical problem to be solved by the utility model is to provide a stable and reliable transformer over-temperature alarm with low cost and no need to design corresponding software programs.

In order to solve the above technical problems, the utility model is a transformer over-temperature alarm, including a temperature sensing circuit, and a drive alarm circuit, the alarm includes a comparator and a preset potential circuit, and the comparator compares the potential of the temperature sensing circuit With the preset potential to drive the alarm circuit to alarm.

Preferably, the preset potential circuit includes a current transformer, the TA1 terminal and the TA2 terminal of the current transformer are respectively connected to any two-phase line on the secondary side of the transformer, and the current transformer is rectified by a rectifier diode and then output to Inverting input of the comparator.

Preferably, an RC filter circuit is further provided between the current transformer and the comparator, and the current transformer is rectified and then output to the inverting input terminal of the comparator after RC filtering.

Preferably, the temperature sensing circuit includes a thermistor RT and a voltage dividing resistor R2, and the voltage dividing point of the thermistor RT and the voltage dividing resistor R2 is connected to the non-inverting input terminal of the comparator.

Preferably, the thermistor RT is a negative temperature coefficient thermistor.

Preferably, the thermistor RT is immersed in transformer oil.

Preferably, the alarm circuit includes a horn and a triode for driving the horn, the base of the triode is connected to the output terminal of the comparator through a current limiting resistor R3, the collector of the triode is connected to the power supply VCC, and the emitter of the triode The pole is connected to the pull-down resistor R4, and the emitter of the triode is connected to the speaker through the capacitor C2.

Beneficial effects: the comparator is used to design the comparison circuit, only need to set a preset potential to compare with the divided voltage potential of the thermistor, then the over-temperature alarm output can be realized, and the alarm horn can be driven to work, the circuit is simple and easy to implement, and There is no need to set up a control chip for detection and driving, which saves costs.

Description of drawings

Below in conjunction with accompanying drawing and specific embodiment the utility model is described in further detail:

Fig. 1 is the schematic diagram of the circuit structure of embodiment 1 of the transformer overtemperature alarm of the present invention;

Detailed ways

Example 1:

The utility model is a transformer over-temperature alarm, which includes a temperature sensing circuit and a driving alarm circuit. The alarm includes a comparator and a preset potential circuit. The comparator drives the alarm circuit to alarm by comparing the potential of the temperature sensing circuit with the preset potential.

As shown in Figure 1, in this embodiment, the preset potential circuit includes a current transformer, and the TA1 and TA2 terminals of the current transformer are respectively connected to any two-phase lines on the secondary side of the transformer, and the current transformer is rectified by a rectifier diode output to the inverting input of the comparator. An RC filter circuit is also provided between the current transformer and the comparator, and the current transformer is rectified and then output to the reverse input terminal of the comparator after RC filtering. The temperature sensing circuit includes a thermistor RT and a voltage dividing resistor R2, and the voltage dividing point of the thermistor RT and the voltage dividing resistor R2 is connected to the non-inverting input terminal of the comparator. The transformer is an oil-immersed transformer, and the thermistor RT is immersed in transformer oil. The alarm circuit includes a horn and a triode driving the horn, the base of the triode is connected to the output terminal of the comparator through a current limiting resistor R3, the collector of the triode is connected to the power supply VCC, the emitter of the triode is connected to the pull-down resistor R4, and the emitter of the triode Pole is connected to the speaker through capacitor C2.

The utility model designs a transformer over-temperature alarm, which can alarm when the temperature rise of the transformer exceeds the set value.

The current transformers TA1 and TA2 are connected to a certain two-phase line on the secondary side of the transformer to induce alternating current. After being rectified by the rectifier diode VD1 and filtered by R5 and C1, a certain potential is obtained at point A and sent to pin 2 of the comparator U1. Immerse the negative temperature coefficient thermistor RT in the transformer oil. When the oil temperature rises, its resistance value becomes smaller, so that the potential of pin 3 of the comparator U1 is greater than that of pin 2, and the output of pin 1 of the comparator U1 is High level, this high level drives the transistor VT to be saturated and turned on, and drives the horn BL to give an alarm.

The comparator is used to design the comparison circuit. It only needs to set a preset potential to compare with the divided voltage potential of the thermistor, and then the over-temperature alarm output can be realized, and the alarm horn can be driven to work. The circuit is simple and easy to implement, and no setting is required. Control chip for detection and drive, cost saving

It should be emphasized that the protection scope of the present utility model includes but is not limited to the above-mentioned specific embodiments. It should be pointed out that for those skilled in the art, some modifications and improvements can be made without departing from the principle of the utility model, and these should also be regarded as belonging to the protection scope of the utility model.

Claims (7)

1. a transformer overtemperature alarm, comprise temperature sense circuit, and drive warning circuit, it is characterized in that, described alarm comprises comparer and preset potential circuit, and described comparer is by the current potential of reduced temperature sensor circuit and preset potential thus drive warning circuit to report to the police.

2. transformer overtemperature alarm according to claim 1, it is characterized in that, described preset potential circuit comprises current transformer, the TA1 end of described current transformer and TA2 end are connected to any two phase lines of Circuit Fault on Secondary Transformer respectively, and described current transformer exports the reverse input end of described comparer to after rectifies.

3. transformer overtemperature alarm circuit according to claim 2, it is characterized in that, also be provided with RC filtering circuit between described current transformer and described comparer, described current transformer exports the reverse input end of described comparer again to after overcommutation through RC filtering.

4. transformer overtemperature alarm according to claim 1, is characterized in that, described temperature sense circuit comprises thermistor RT and divider resistance R2, and described thermistor RT is connected the input end in the same way of described comparer with divider resistance R2 dividing point.

5. transformer overtemperature alarm according to claim 4, is characterized in that, described thermistor RT is negative tempperature coefficient thermistor.

6. transformer overtemperature alarm according to claim 4, is characterized in that, described thermistor RT is immersed in transformer oil.

7. transformer overtemperature alarm according to claim 1, it is characterized in that, warning circuit comprises loudspeaker, drives the triode of described loudspeaker, the base stage of described triode connects the output terminal of described comparer by current-limiting resistance R3, the collector of described triode meets power supply VCC, the emitter of described triode meets pull down resistor R4, and the emitter of described triode connects described loudspeaker by electric capacity C2.