In the high-voltage switchgear due to copper oxide corrosion, bolt loose caused by temperature rise, if not timely maintenance will cause a major security incident, take a look at the scene.
With the increasing demand for electricity for people to pay more and more attention to electricity safety, high voltage switchgear temperature has been the focus of attention. As the wireless zigbee technology more and more popular, this program is a good solution to the high voltage switchgear copper temperature monitoring problem. But this program is also flawed, how to do low power consumption and small size, rapid development has been limited to the application of wireless temperature. Switch cabinets in the layout of the copper can not have a larger idle position, are generally used to install the strap, this method requires the temperature to collect the module to do a very small volume. As the scene is not convenient to take electricity, so the use of battery-powered, the entire temperature acquisition module life of at least 3 years, in order to do insulation security are used to seal the battery method is also very convenient to replace the battery. General wireless temperature acquisition and more use: MCU + zigbee + temperature sensor, this program bulky, power consumption, development cumbersome, the following to introduce a more convenient and practical program.
Figure 1 Wireless temperature acquisition strap
一、zigbee + temperature sensor integration solution
In order to reduce power consumption and control the volume, can not increase the additional MCU, all the acquisition control must be completed in the zigbee module. In order to zigbee module sleep when the entire system does not consume power, the temperature sensor DS18B20 set to single-wire communication mode, when the zigbee sleep DS18B20 does not consume power. When the zigbee module wakes up the acquisition, the zigbee communicates with the temperature acquisition module and simultaneously charges the capacitor in the temperature sensor DS18B20. Users can set the sleep wake-up time by the host computer software, you can set in accordance with the seconds can also be set in accordance with the points. After the module is configured, the module will wake up. When the module is awakened, the temperature is collected and sent to the master node through the zigbee network. After the transfer is completed, it will enter the sleep again. Central This program is not only low power consumption and small size, and then greatly shorten the user's R & D cycle, the user only need to focus on their own node research and development, from the node only through the configuration can be.
Figure 2 temperature acquisition block diagram
The zigbee module and the battery are integrated into a strap, and then the strap is tied to the bronze medal, and the back of the strap is open to facilitate contact with the measured bronze.
Figure 3 on-site installation of the picture
The entire network uses a star network topology, the switchboard in the intelligent control switch as the main node, the temperature acquisition strap as a child node, the child node to collect the collected temperature and then sleep again. The main nodes are connected through the RS-485 network, and then through the GPRS DTU transmission to the monitoring background.
Figure 4 block diagram of the wireless temperature measurement system
二、the core components: zigbee module introduced
1、ultra-small size
The program uses Guangzhou Zhiyuan research and development of low-power small-volume Nano-type zigbee module, as shown below zigbee module generally use ceramic antenna, low power module size can be 13.5mm * 16.5mm, on the standard strap just Appropriate if the volume is too big to put a little bit. The entire module with a stamp hole in the way the height is just right, if the use of the way the needle and then calculate the thickness of the floor height is too high.
Figure 5 zigbee module volume
2、super power consumption
The module not only has an ultra-small size also has ultra-low power consumption, as shown in the table below the small power module to send current is only 20mA, sleep only 160nA in accordance with 2 minutes to wake up a theory can work 5-6 years.
Figure 6 zigbee module power consumption
The following figure is similar products power comparison
Figure 7 Comparison of power consumption
3、3.6V power supply, no other power supply module
Commonly used ER14250H batteries are 3.6V power supply, ZLG far from the electronic Nano module supports 3.6V power supply, no other devices to avoid increased power consumption to increase the volume.
Figure 8 Battery
4、support the host computer software configuration, product development speed
Nano module supports the host computer software configuration, you can set the master node ID and sleep collection time, to achieve 0 code control.
Figure 9 PC software configuration
三、the temperature sensor introduced
The program uses DS18B20 as a temperature sensor, the sensor is small to install, Harvatek can use single-wire communication does not require additional power interface, zigbee module sleep when the DS18B20 in the off state.
Figure 10 single-wire power supply
