CN107765743A - Power auto-adjustment type switch cubicle temperature and humidity control device based on temperature difference control - Google Patents

Abstract

The invention discloses a power automatic adjustment type switch cabinet temperature and humidity control device based on temperature difference control, including a temperature and humidity sensor inside the cabinet, a temperature and humidity sensor outside the cabinet, a temperature and humidity sensor inside the cabinet, a temperature and humidity sensor outside the cabinet, and a temperature and humidity controller Connection, the temperature and humidity controller is connected with the exhaust heater, and the switching power supply provides power for the temperature and humidity controller. The temperature and humidity control device of the switch cabinet of the present invention is easy to install and flexible to operate, reduces the occurrence of power equipment damage accidents caused by humidity, reduces the workload of patrol inspection and maintenance, and improves the reliability of power supply and the reputation of electricity sales and electricity sales, which has important advantages. economic and social effects.

Description

Temperature and humidity control device for automatic power regulation switchgear based on temperature difference control

technical field

The invention relates to a temperature and humidity control device for a switch cabinet.

Background technique

Condensation is a very common physical phenomenon in nature. When the surface of an object in contact with the air is lower than the temperature of the air, condensation will occur on the surface.

In the case of drastic changes in external temperature and humidity, condensation will also occur inside the switchgear, which may cause the following hazards.

(1) The operating mechanism and secondary equipment in the cabinet are corroded and mildewed, reducing the service life of the equipment.

(2) DC grounding, causing the protection device to malfunction or refuse to operate.

(3) The screws and connecting pieces of the terminal block are rusted and cause poor contact, which makes the secondary circuit open, and the protection device refuses to operate or malfunctions.

At present, a temperature and humidity controller is installed in the cabinet to control the heater to dehumidify the switch cabinet. This method will still produce condensation when the temperature difference changes greatly, and it cannot prevent the condensation of the switch cabinet. Such an unscientific heating method On the one hand, it leads to high energy consumption, and on the other hand, it also leads to high local temperature, which accelerates the aging of insulation and electrical equipment.

How to prevent power accidents caused by condensation in switch cabinets has become a difficult problem for power supply companies.

Contents of the invention

The object of the present invention is to provide a temperature and humidity control device for a switch cabinet with automatic power regulation based on temperature difference control with good working performance.

Technical solution of the present invention is:

A temperature and humidity control device for automatic power adjustment switchgear based on temperature difference control, which is characterized by: including a temperature and humidity sensor inside the cabinet, a temperature and humidity sensor outside the cabinet, a temperature and humidity sensor inside the cabinet, a temperature and humidity sensor outside the cabinet, and a temperature and humidity controller connection, the temperature and humidity controller is connected with the exhaust heater, and the switching power supply provides power for the temperature and humidity controller; the temperature and humidity sensor in the cabinet includes the first high-precision temperature and humidity sensor, the first MCU, the first RS485 communication module, and the first A high-precision temperature and humidity sensor is connected to the first MCU, and the first MCU is connected to the first RS485 communication module; the temperature and humidity sensor outside the cabinet includes a second high-precision temperature and humidity sensor, a second MCU, and a second RS485 communication module. Two high-precision temperature and humidity sensors are connected with the second MCU, and the second MCU is connected with the second RS485 communication module; the temperature and humidity controller includes the MCU of the temperature and humidity controller, and the MCU of the temperature and humidity controller is connected with a clock chip and a memory chip. , liquid crystal display, setting buttons, current acquisition module, RS485 bus and PWM output unit; the exhaust heater includes a heater and a turbofan;

The current acquisition module of the temperature and humidity controller collects the working current of the exhaust heater, and the MCU of the temperature and humidity controller determines whether the exhaust heater is working normally;

The RS485 bus of the temperature and humidity controller is connected with the first RS485 communication module and the second RS485 communication module, and the temperature and humidity information in the cabinet and the temperature and humidity information outside the cabinet are passed to the MCU of the temperature and humidity controller; The MCU uses different PWM to control the heating power of the heater according to the dew point temperature under the relative temperature and humidity, so that the condensation condition cannot be satisfied in the cabinet.

The temperature and humidity controller is installed on the panel of the switch cabinet. The panel has a round hole with a diameter of 25mm. The power line and control line are connected to the equipment installed in the cabinet through the round hole.

The exhaust air heater includes a stainless steel shell, and a PTC heater and a turbo centrifugal fan are arranged in the stainless steel shell.

The liquid crystal display is a 3.2-inch color liquid crystal display.

The first high-precision temperature and humidity sensor is a high-precision temperature and humidity sensor Si7021.

The second high-precision temperature and humidity sensor is a high-precision temperature and humidity sensor Si7021.

The beneficial effect of the present invention is that, after the design of the new device, the temperature and humidity control device of the switchgear is easy to install and flexible to operate, reduces the occurrence of power equipment damage accidents caused by moisture, reduces the workload of inspection and maintenance, and improves the reliability of power supply at the same time. Reputation and electricity sales have important economic and social effects. There are currently tens of thousands of substations, and each substation has a large number of switchgears. There is a huge market demand, and the economic and social benefits are very considerable. The device is easy to operate, reliable in performance, energy-saving, solves the power safety accidents caused by equipment condensation, and improves the reliability of power supply equipment.

Description of drawings

The present invention will be further described below in conjunction with drawings and embodiments.

Fig. 1 is a structural schematic diagram of an embodiment of the present invention.

Figure 2 is a schematic diagram of the clock circuit.

Fig. 3 is a circuit diagram of a memory chip.

Figure 4 is a circuit diagram of the current acquisition module.

Figure 5 is a circuit diagram of the RS485 bus.

Figure 6 is a solid state relay control circuit.

Detailed ways

A temperature and humidity control device for automatic power adjustment switchgear based on temperature difference control, including a temperature and humidity sensor inside the cabinet, a temperature and humidity sensor outside the cabinet, the temperature and humidity sensor inside the cabinet, the temperature and humidity sensor outside the cabinet are connected to the temperature and humidity controller, the temperature and humidity The controller is connected with the exhaust heater, and the switching power supply provides power for the temperature and humidity controller; the temperature and humidity sensor in the cabinet includes a first high-precision temperature and humidity sensor, a first MCU, a first RS485 communication module, and a first high-precision temperature and humidity sensor. The humidity sensor is connected with the first MCU, and the first MCU is connected with the first RS485 communication module; the temperature and humidity sensor outside the cabinet includes the second high-precision temperature and humidity sensor, the second MCU, the second RS485 communication module, and the second high-precision temperature and humidity sensor. Humidity sensor is connected with the second MCU, and the second MCU is connected with the second RS485 communication module; Described temperature and humidity controller comprises the MCU of temperature and humidity controller, and the MCU of temperature and humidity controller is connected with clock chip, memory chip, liquid crystal display, Set buttons, current acquisition module, RS485 bus and PWM output unit; the exhaust heater includes a heater and a turbofan.

(1) Partial design of the temperature and humidity controller

The temperature and humidity controller is composed of microcontroller MCU, liquid crystal display module, clock unit, storage unit, current acquisition unit, RS485 bus, PWM control output, system setting unit and other modules.

The technical principles of each functional module are as follows:

1), micro-processing unit MCU

The new generation of MCU-STC12LE5A60S2, which adopts Hongjing Technology's high-speed/low power consumption/super anti-interference, is 8-12 times faster than ordinary MCUs. 2-way PWM, 8-way high-speed 10-bit A/D conversion (250K/S).

2) clock

design description:

DS1302 trickle charge clock chip, a high-performance, low-power real-time clock chip, with 31 bytes of static RAM, uses SPI three-wire interface to communicate with CPU synchronously, and can transmit multiple bytes at a time in burst mode clock signal and RAM data. The real-time clock can provide seconds, minutes, hours, days, weeks, months, and years. The hour and 31 days of a month can be automatically adjusted, and it has a leap year compensation function. It adopts dual power supply (main power supply and backup power supply), and the charging mode of backup power supply can be set, which provides the ability to charge the back power supply with trickle current. It is used to regularly record the temperature and humidity values inside and outside the cabinet.

3) storage

Using advanced ferroelectric technology. A Ferroelectric Random Access Memory or FRAM is non-volatile and performs reads and writes like RAM. It provides reliable data retention while eliminating the complexity and the ability to stream charge EEPROMs and other non-volatile memories that pose system-level reliability issues.

The device records the historical data of temperature and humidity inside and outside the cabinet, so that inspection personnel can check the temperature and humidity of the switch cabinet. to the working condition of the device.

4) Current collection

design description:

Since the exhaust heating device is installed inside the switch cabinet, the inspection personnel cannot know the fault status information of the heating device during the inspection, and the current collects the working current of the heating device to determine whether it is working normally.

The current signal is collected by the current transformer, and then the collected voltage signal is amplified by the operational amplifier and then sent to the AD collection port of the MCU. Since the MCU comes with a 10-bit AD chip, the AD collection circuit is omitted, and the MCU directly transmits the voltage data. Read in and analyze.

5) RS485 communication protocol

design description:

The differential signal A1 and B1 are respectively connected to a fuse SMD005, which can protect the SP3485 chip, and the differential signal is respectively connected to a SMBJ-5V regulator tube to clamp the voltage between the differential and ground within 5V to prevent pulse signal damage other electronic components. The MCU reads in the values of the temperature and humidity sensors inside and outside the cabinet through RS485.

6) PWM control output

For the dew point temperature under relative temperature and humidity, different PWMs are used to control the heating power of the heater. For example: at a dew point temperature of 23.2°C with a relative temperature of 25°C/humidity of 90%RH, the solid state relay is controlled to adjust the working power of the heater, so that the cabinet The internal dew point temperature is greater than 23.2°C, making the cabinet unable to meet the condensation conditions.

5 gears are used to adjust the heating power. It is realized by controlling the heating cycle of heating and the duty cycle of heating. The solid-state relay used in the control circuit switches the power supply of the heater. The solid-state relay (SSR) is a component of a full electronic circuit combination, which relies on semiconductor devices and electronic components. Electromagnetic and optical characteristics to complete its isolation and relay switching functions. Compared with the traditional electromagnetic relay, the solid state relay is a relay without machinery and no moving parts, but it has essentially the same function as the electromagnetic relay. It is widely used in industrial automation control, such as electric furnace heating system, familiar control machinery, remote control machinery, motors, solenoid valves and signal lights, scintillators, stage lighting control systems, medical equipment, copiers, washing machines, fire protection and security systems, etc. . Reliable work, no contact, no spark, long life, no noise, no electromagnetic interference, fast switching speed, MCU achieves the purpose of directly driving large current loads with tiny control signals.

(2) Partial design of the temperature and humidity sensor inside the cabinet and the temperature and humidity sensor outside the cabinet

This part includes: the temperature and humidity sensor inside the cabinet, the temperature and humidity sensor outside the cabinet consists of a micro-processing unit, a high-precision temperature and humidity sensor, an RS485 communication module, and a power conversion circuit.

design description:

Through the temperature and humidity values inside and outside the sampling cabinet, the dew point value is calculated to control the heater. According to the dew point curve, the heater is controlled so that the temperature and humidity in the cabinet are within the dew point temperature value under the relative temperature and humidity, so that the cabinet cannot meet the condensation temperature. exposed conditions.

1) High precision temperature and humidity sensor:

This project chooses to use imported high-precision temperature and humidity sensor Si7021 without calibration. It is a digital temperature and humidity sensor with an I2C interface. The MCU reads the temperature and humidity through the I2C bus without the error of the analog chip through AD conversion.

2) Power conversion:

Since the power supply is supplied by an external switching power supply, the input voltage is 12V, and the operating voltage of the processor is 3.3V, so a high-efficiency power converter is needed for voltage conversion.

The MC33063 single-chip DC-DC converter is used, and the converter can be combined with a small number of external components to form a step-down converter with an efficiency of up to 93%. The input voltage range of the circuit is 5-40V, the output current is 1.5A, and there is current Restricted functionality.

(3) Partial design of the exhaust heater

The exhaust heater consists of a PTC heater and a turbo centrifugal fan.

1. Design description

1) PTC heater: PTC heater with constant temperature heating element, small size, constant temperature heating, high heat conversion rate, little influence by power supply voltage, long natural life and so on.

2) Turbo centrifugal fan: The turbo centrifugal fan can realize side air outlet, and control the dew point temperature more quickly and evenly by circulating the air in the cabinet.

3) Shell: The shell is made of 304 stainless steel, so that the shell will not rust for a long time and maintain a brand new state. The shell is designed with a variety of installation brackets, which can be installed on the side wall or on the base of the cabinet.

2. How to use

1) Install the heater on the fixing bracket, drill 2 M4 holes on the side wall of the switch cabinet, and fix the heater on the side wall of the switch cabinet with M4 screws.

2) Installation of the temperature and humidity sensor in the cabinet: fix the fixed guide rail on the side wall of the other side of the switch cabinet, then clamp the temperature and humidity sensor in the cabinet on the guide rail, and screw on the fixing clip.

Installation of the temperature and humidity sensor outside the cabinet: the same first fix the guide rail on the cabinet door, and then fix the sensor on the guide rail.

Installation of the controller: Open a 25mm round hole on the cabinet door, and then open two 4mm holes, screw on the fixing screws and hang the controller directly on the screws.

Fixing of switching power supply: Fix the rail-type switching power supply in the instrument compartment of the switch cabinet through the rail.

After the installation of the above equipment is completed, connect the wires of the exhaust heater, the temperature and humidity sensor inside and outside the cabinet, and the switching power supply to the controller.

After the power is turned on, the device will run automatically, and the main interface will display the temperature and humidity values inside and outside the cabinet and the operating status level.

Claims (6)

1. A temperature-humidity control device for automatic power-adjusting switchgear based on temperature difference control, characterized in that it includes a temperature-humidity sensor inside the cabinet, a temperature-humidity sensor outside the cabinet, a temperature-humidity sensor inside the cabinet, a temperature-humidity sensor outside the cabinet and a temperature-humidity sensor The controller is connected, the temperature and humidity controller is connected with the exhaust heater, and the switching power supply provides power for the temperature and humidity controller; the temperature and humidity sensor in the cabinet includes the first high-precision temperature and humidity sensor, the first MCU, and the first RS485 communication module , the first high-precision temperature and humidity sensor is connected to the first MCU, and the first MCU is connected to the first RS485 communication module; the temperature and humidity sensor outside the cabinet includes a second high-precision temperature and humidity sensor, a second MCU, and a second RS485 communication module , the second high-precision temperature and humidity sensor is connected with the second MCU, and the second MCU is connected with the second RS485 communication module; the temperature and humidity controller includes the MCU of the temperature and humidity controller, and the MCU of the temperature and humidity controller is connected with a clock chip, memory chip, liquid crystal display, setting button, current acquisition module, RS485 bus and PWM output unit; the exhaust heater includes a heater and a turbofan; The current acquisition module of the temperature and humidity controller collects the working current of the exhaust heater, and the MCU of the temperature and humidity controller determines whether the exhaust heater is working normally; The RS485 bus of the temperature and humidity controller is connected with the first RS485 communication module and the second RS485 communication module, and the temperature and humidity information in the cabinet and the temperature and humidity information outside the cabinet are passed to the MCU of the temperature and humidity controller; The MCU uses different PWM to control the heating power of the heater according to the dew point temperature under the relative temperature and humidity, so that the condensation condition cannot be satisfied in the cabinet. 2. The temperature and humidity control device for automatic power adjustment switch cabinet based on temperature difference control according to claim 1, characterized in that: the temperature and humidity controller is installed on the panel of the switch cabinet, and the panel has a round hole with a diameter of 25mm. The round holes connect the power and control wires to the equipment installed in the cabinet. 3. The temperature and humidity control device for automatic power regulation switchgear based on temperature difference control according to claim 1, characterized in that: said exhaust heater, the heater includes a stainless steel shell, and a PTC heater and a turbine are arranged in the stainless steel shell. centrifugal fan. 4. The temperature and humidity control device for automatic power adjustment switchgear based on temperature difference control according to claim 1, characterized in that: the liquid crystal display is a 3.2-inch color liquid crystal display. 5. The temperature and humidity control device for automatic power regulation switchgear based on temperature difference control according to claim 1, characterized in that: the first high-precision temperature and humidity sensor is a high-precision temperature and humidity sensor Si7021. 6 . The temperature-humidity control device for automatic power-adjusting switchgear based on temperature difference control according to claim 1 , characterized in that: the second high-precision temperature-humidity sensor is a high-precision temperature-humidity sensor Si7021.