JPH058664Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention measures the oil temperature of a large-capacity transformer such as a substation and the outside air temperature, and uses the temperature difference to adjust the oil temperature of the transformer appropriately. This invention relates to an oil temperature control device for a transformer to be controlled.

[Conventional technology]

As is well known, conventional transformer oil temperature control devices measure the oil temperature with a dial thermometer in order to properly manage the oil temperature of the transformer during operation. If the temperature is higher than the set value, the contact is closed, the cooling oil pump is activated via the control circuit to force oil circulation, and an alarm is activated if the oil temperature rises excessively. Further, the set values for operating the alarm and the cooling oil pump are set by taking into consideration the average outside temperature and the load situation in each season.

[The problem that the idea attempts to solve]

Conventional transformer oil temperature control devices start the cooling oil pump based on the oil temperature, which takes into account the outside air temperature, so the set value must be changed depending on the season, and the dial is affected by daily weather conditions. There was a problem in that the thermometer reacted unnecessarily due to the influence of the surrounding outside air temperature, activating the alarm and the cooling oil pump, and wasting power. Additionally, there was a problem in that the cooling oil pump was forced to respond unnecessarily during light loads.

This idea was made to solve the above problems, and it is a transformer oil temperature control that eliminates the need to change set values depending on the season and eliminates unnecessary responses due to changes in outside temperature. The purpose is to provide equipment.

[Means to solve the problem]

The oil temperature control device for a transformer according to this invention includes an oil temperature sensor section that measures the oil temperature, an outside air temperature sensor section that measures the outside air temperature, and an arithmetic means that calculates the difference temperature obtained by subtracting the outside air temperature from the oil temperature. and a comparison means for comparing the temperature difference and a pump start setting value for starting the cooling oil pump, and outputs an output signal for operating the pump start output contact based on the comparison result. be.

[Operation] The transformer oil temperature control device in this invention is as follows:
The temperature difference between the oil temperature and the outside air temperature is compared with a pump activation set value, and the cooling oil pump is operated based on the comparison result to circulate the oil in the transformer.

〔Example〕

An embodiment of this invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of this invention. In the figure, 1 is a transformer (not shown).
The oil temperature sensor part consists of an oil temperature sensor 1a and a sensor amplifier 1b that measure the oil temperature.The oil temperature sensor 1a uses a temperature-sensitive resistor whose resistance value changes linearly with temperature. This temperature-sensitive resistor and a reference resistor whose resistance value does not change with temperature are connected in series, a reference voltage is applied, and the change in resistance value due to temperature change is extracted as a voltage. Further, the sensor amplifier 1b is composed of a circuit that generates the reference voltage and a circuit that amplifies the voltage with respect to temperature. That is, the reference voltage uses a temperature-compensated constant voltage diode to supply a stable voltage with no temperature change to the oil temperature sensor 1a. Further, the amplifier circuit amplifies the voltage from the oil temperature sensor 1a using an operational amplifier. Reference numeral 2 denotes an outside air temperature sensor section consisting of an outside air temperature sensor 2a and a sensor amplifier 2b, which has the same configuration as the oil temperature sensor section 1. 3 is an analog switch (not shown) that selects between the oil temperature signal and the outside air temperature signal, and an analog switch (not shown) that converts the analog voltage selected by this analog switch into a digital signal.
An A/D converter consisting of a D conversion section (not shown), 4 ₁ , 4 ₂ , 4 ₃ , 4 ₄ are I/O ports, and 5 is an I/O port.
This CPU controls each circuit such as outputting a switching signal to an analog switch based on a program stored in advance in ROM 6, reads temperatures, calculates temperature differences, and performs comparison judgments.
Ports ₄₁ to ₄₄ , ROM6, and RAM7 constitute a microcomputer 8. 9 is I/O port 4
A display driver receives a temperature signal from ₄ and converts it into a 7-segment display element drive signal; 10 is a display that emits light based on the drive signal from the display driver 9; 11 is an I/O port ₄₄ and a failure detection circuit 12 to be described later. 13 is a pump starting driver 11 that operates a relay (not shown) based on a signal from the pump and outputs a contact signal to the outside.
14 is a runaway check circuit that constantly monitors the operation and voltage inside the microcomputer 8 and resets the CPU 5 as necessary.This runaway check circuit 14 uses a watchdog timer. There is. In addition, the failure detection circuit 12
outputs a failure signal to the pump start driver 11 and the alarm driver 13 when the number of pulses as a reset signal from the runaway check circuit 14 is greater than or equal to a predetermined number. Further, a control section 15 is composed of the A/D converter 3, the microcomputer 8, the drivers 9, 11, and 13, the display 10, the failure detection circuit 12, and the runaway check circuit 14. 16 is a display switching switch that supplies a display switching signal to the CPU 5 via the I/O port ₄₃ .

Next, the operation will be explained.

The oil temperature sensor 1a measures the oil temperature of the transformer, and the outside temperature sensor 2a measures the outside air temperature and converts it into an electrical signal (analog signal). Then, the voltage from the oil temperature sensor 1a and the outside temperature sensor 2a
The voltage from the control unit 1 is amplified by sensor amplifiers 1b and 2b each composed of an operational amplifier.
Supply to 5. A/D converter 3 of control unit 15
Based on the switching signal from the CPU 5, the analog switch supplies the oil temperature signal or the outside air temperature signal to the A/D converter and converts it into a digital signal. One oil temperature digital signal is I/O port 4
₁ and is calculated by the CPU 5 via the I/O port 4 ₄ and the display driver 9 as the oil temperature on the display 10, and the other outside air temperature digital signal is also calculated by the CPU 5 via the I/O port 4 ₁ . The display changeover switch 16 is switched and the display 10 is displayed via the I/O port ₄₄ and the display driver 9.
is displayed as the outside temperature. In addition, the display 10
The difference temperature (temperature increase) obtained by subtracting the outside air temperature from the oil temperature calculated by the calculation means of the CPU 5 can also be displayed.

Furthermore, the CPU 5 reads the alarm set value and the pump start set value, and compares and calculates each set value and the difference temperature using the comparison means. If the difference temperature is higher than the pump start set value, the I/O port ₄ and the pump start driver 11 to operate the cooling oil pump output contact. Further, if the differential temperature is higher than the alarm set value, the alarm output contact is operated via the I/O port ₄₄ and the alarm driver 13.

In addition to this, CPU5 also measures the oil temperature.
The maximum oil temperature value stored in the RAM 7 is compared with the measured value, and if the measured value is higher, it is transferred to the RAM 7 and processing is performed to store the measured value as a new maximum oil temperature value.

[Effect of idea]

As described above, according to this invention, the oil temperature control device of the transformer compares the temperature difference obtained by subtracting the outside air temperature from the oil temperature with the pump start setting value, and if the difference temperature is higher, starts the cooling oil pump. Since the configuration is such that the oil is forced to circulate, it is possible to properly control the temperature, and since it is not affected by the ambient temperature such as outside air, the cooling oil pump does not need to respond unnecessarily, allowing for proper cooling. The effects of maintenance and power saving through oil pump operation, as well as stable power supply, can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a transformer oil temperature control device according to this invention. 1...Oil temperature sensor section, 2...Outside air temperature sensor section, 5...CPU.

Claims (1)

[Scope of utility model registration request] In a transformer oil temperature control device that measures the oil temperature in a transformer and operates a cooling oil pump to circulate the oil when the oil temperature exceeds a set value, the oil temperature is an oil temperature sensor section to measure, an outside air temperature sensor section to measure the outside air temperature, a calculation means for calculating a difference temperature by subtracting the outside air temperature from the oil temperature, and a calculation means for calculating the difference temperature obtained by this calculation means and the above set value. and comparing means for comparing and outputting an output signal for operating a pump start output contact of the cooling oil pump when the difference temperature is higher than a set value.