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Brief Overview Of The Cooling Tower Fan Frequency Control
Aug 08, 2017

Brief overview of the Cooling Tower fan frequency control
The design of the contents of the PLC control of the Cooling Tower fan frequency control system, mainly used in the PLC, touch screen and inverter. Cooling Tower fan frequency control system is equipped with a frequency converter, a fan for frequency control, the other two fan power frequency operation; according to changes in the water temperature to control the frequency of running fan start and stop, to achieve the initial adjustment of water temperature , And a fan for frequency control, the water temperature fine-tuning, so that the Cooling Tower within the water temperature control in a stable state. Keywords: programmable logic controller (PLC), frequency converter, touch screen With the continuous development of frequency conversion technology and the improvement of human energy awareness, the application of various frequency conversion devices in the global industry has produced significant economic benefits.
 【Design】 through the installation of the water mains on the temperature sensor, the water temperature signal into a 4-20mA standard signal into the PLC's analog input module, and eventually converted to the corresponding value (BCD code), through the compiled PLC program, the resulting value and the temperature set in the touch screen to compare, get a comparison parameter, sent to the inverter, the inverter control of a motor speed, and according to the level of water temperature, by the PLC control workers Frequency of the start of the fan, so that the Cooling Tower back to the temperature control in the set temperature.
The Cooling Tower fan using frequency control, should also note the following points.
(1) As the Cooling Tower fan drive part of the moment of inertia are generally large, so given a certain acceleration and deceleration time longer, such as 30 ~ 50s.
(2) in the actual operation will often be due to the role of external wind cooling fan rotation, then start the inverter, the motor will enter the regeneration state, there will be a fault trip. For the inverter should be set to start the speed tracking and then restart, so that you can start before the drive, by detecting the motor speed and direction to achieve the rotation of the motor smooth and no impact start.
   (3) Since it is an ordinary motor, it should be set to the minimum operating frequency to maintain the appropriate temperature rise of the motor, usually the lower frequency limit of 20Hz.
(4) In order to prevent the mechanical resonance phenomenon of the cooling fan at a specific speed in the wide operating frequency range (usually 20 ~ 50Hz), this should be analyzed in the test run and the method of modifying the parameters will be used to convert the natural frequency As the jump frequency.
 Industrial production or refrigeration process generated waste heat, generally with cooling water to guide away. From the river, river, lake, sea and other natural water to absorb a certain amount of water as cooling water, cooling process equipment to absorb waste heat to water temperature, and then into the river, river, lake, sea, this cooling method known as DC cooling The When the DC cooling conditions are not available, the Cooling Tower needs to be cooled.
The role of the Cooling Tower is equivalent to ordinary household air conditioning outdoor unit heat exchanger, is used to heat the equipment.
For the water-cooled central air-conditioning water, the condensation side is the water pump through the pipeline to remove the water inside the condenser heat, the water after the condenser to take away the heat, the role of the pump into the Cooling Tower, Through the flow of water in the Cooling Tower and then the heat transfer to the Cooling Tower around the air, and then re-enter the central air conditioning condenser to absorb heat.
Water-cooled central air-conditioning system Cooling Tower is equivalent to ordinary household air-conditioning outdoor unit on the condenser, the pump is equivalent to ordinary household air-conditioning outdoor unit fan motor, only by a heat exchanger into a secondary heat exchange only.
Water-cooled central air-conditioning cooling water system Because it is open system, water quality is very easy to become poor, need regular cleaning pipes, regular replacement of cooling water.