Good omen GME11Y24 20 kw TV transmitter type cooling system

Taishan station in January 2016, installing a tongfang good omen GME11Y24 20 kw TV transmitter, as for machine use of shandong TV, transmitter for the cooling system of surface. The cooling efficiency, has long been regarded as important factors which influence the stability of transmitter operation. Compared with the conventional air-cooled transmitter, liquid-cooled transmitter has the characteristics of high reliability and high cooling efficiency. It is not only the noise of the device working, reduce energy consumption, improve the efficiency of heat source of heat, but also prolong the service life of LDMOS transistors. Surface technology to enhance the stability of the transmitter and reduce the failure rate of the transmitter.

the transmitter since running, simple operation, easy maintenance, for my safety and quality of the broadcast work provides an important support. But because of the transmitter is Beijing tongfang good omen for me tailor-made high-power liquid-cooled transmitter, in the overall design and manufacturing process has certain defects, transmitter in operation process is not very stable. 12 three synthesizer power amplifier unit, four, three two synthesizer and 30 switch power supply is installed on the same machine cabinets, cause all the equipment together, is not conducive to heat dissipation. While the transmitter cooling ways adopted cools, cooling efficiency is higher, but the liquid-cooled system is only to cool power amplifier unit, but in the rest of the equipment rack temperature too high. Cabinet temperature is higher than room temperature 15 ℃ above, due to launch rooms adopt circulating cooling fan, no precision air conditioning cooling, summer room temperature can reach 30 ℃, cabinet temperature can reach more than 45 ℃, exist hidden dangers for safety broadcast. As a result of the power amplifier unit level at the end of the power tube adopts LDMOS transistors, LDMOS transistors has the characteristics of negative temperature coefficient, and as the temperature increases, the transistor drain current decreases, the output power of power amplifier unit is reduced, which affect the transmitter of the machine efficiency. In addition, the temperature is too high, will seriously affect the service life of the transistor, easy to cause the damage of power amplifier tube. Transmitter of safety, economy, there are hidden dangers.

in order to facilitate cooling, we use a state intelligent temperature control instrument, a thermocouple, an ac contactor, three small axial flow fan with power frequency. Schematic diagram is shown in figure 1.

logical sequence according to the transmitter switch machine, we will be working temperature controller input voltage by the transmitter board W3/4 - X2 patch panel 1,W3/4 - Two set point, the two set points for transmitter actuator power supply, the voltage is 220 v. Switch machine instructions that are executed transmitter, temperature controller and driver to work together. Ac contactor input from the transmitter surge protector backend, input power surge protection function.

thermocouple acquisition cabinet inside the environment temperature, when the thermocouple acquisition environment temperature is higher than the temperature controller set start temperature, the temperature controller output control signal, Line voltage) Control of ac contactor action, control of three axial flow fan working. Three axial flow fan, one as a fan, the other two as a fan, install it in transmitter power amplifier inside, as the transmitter of auxiliary cooling, cooling effect.

the model of axial flow fan is: fzy - 200 D, the rated working voltage of 220 v, 65 w. The fan has the characteristics of high efficiency heat dissipation, low noise mute. Axial flow fan in the working voltage is 220 v, 380 v fan wiring way is different. Line of 380 v fan to adjust any two phase sequence can change the direction of the rotation of the fan. 220 v fan work with startup capacitor, specific connection as shown in figure 2.

220 v axial flow fan with two windings, start and run the windings, respectively, the startup winding resistance is small, running winding resistance is bigger. Measuring 220 v axial flow fan 3 root value of arbitrary two, will start the capacitance in resistance between the two largest line ( As shown in figure 2) , run the windings to 220 v, through cross 1, 2, terminal wiring can be 220 v fan rotation direction.

terminal 8, 9 at the transmitter board W3/4 - X2 patch panel 1,W3/4 - Two set point, when the transmitter to execute commands on, the voltage is 220 v, temperature controller starts to work. 220 v input wire access terminal 10, the relay temperature controller output interface using out2 / alarm ( Terminal 10, 11) When the thermocouple acquisition environment temperature is higher than when the temperature controller set the action of temperature, is conducting terminals 10 and 11. When temperature controller action, terminals 11 ( Wire) Connect ac contactor voltage at one end of the line package, the other end of the line voltage of 220 v input zero line, ac contactor and at this time, three power frequency fan began to work.

the thermostat parameter Settings: PV value measurement showed that the SV value display. Press set key, display setting parameters in accordance with the order. 5 seconds press set key, enter the parameter setting state, the LKV ( Parameters of the lock) Set to 1, parameters can be modified. 光伏( Proportional band) Set to 0, DV, Differential time) Set to 2, SPV ( Ratio with separation) Set to 0.

after a period of trial, the transmitter power amplifier incase of temperature and environmental temperature, compared to a drop of more than 8 ℃, the cooling effect is obvious. Stable at about 19 kw transmitter power, power amplifier tube failure rate significantly reduced. Improve the stability of transmitter operating, provides guarantee for safety and quality broadcast work.

related: wear-resistant thermocouple

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