Reducing loads in series connection
Fan control unit with "EXHAUST" speed controller
The software part
At a brick factory, when a large amount of equipment is started, there is a sharp current surge. To prevent this from happening, a cascade circuit is used to turn on the devices. One by one. This algorithm is used to control the discrete relay output of the fan, as well as the analog output for solving the problem of regulating the speed of rotation — the EXHAUST function block.
Processes the input values of the technological process and generates the output discrete and analog signals necessary to control the fan with a speed controller. The operation of the fan at low speeds is not a typical task, leading to its overheating, for this the functional unit has protection from issuing an executive command to the variator below 20%. The fan speed controller requires a gentle supply of the executive command (SPEED), in this regard, the unit has the function of smoothing the output value, in order to avoid sudden shocks during switching on or off the fan motor. Discrete violations ALARM1 (fan belt breakage), ALARM2 (variator malfunction), ALARM3 (unreliable status status) are generated only after the fan is turned on, and are reset if there are no reasons that caused them and the unit is restarted. When a new violation occurs, the discrete output of the block (OUT) is reset, which leads to the shutdown of the associated equipment. The unit provides protection against the possibility of frequent on-off by the operator. This means that the operator does not have the opportunity to turn on the fan immediately after turning it off once, it is required to wait at least 20 seconds, after which permission to turn on the fan appears.
Assignment of inputs and outputs of the function block
Inputs: Type Description
Fan status
Fan belt condition
Block blocking
Control signal from the system controller
The command to start from the system algorithm
Command to stop from the system algorithm
Condition of the variator
Selecting the operating mode of the unit
Inputs: Type Description
Command on the variator relay
Analog output to the fan variator
Breakage-slipping of the fan belt
Unreliable fan condition
The variator is faulty The command to start from the operator key
The command to start from the operator key
Application Features
This functional unit can be used with any motorized devices that have a speed controller.
Recommendations for use
The analog output from the unit is transmitted to the field value translation unit, and then transmitted to the 0-20 mA analog output. The input analog channel CMD is linked to the output of the functional unit of the PID controller.
#Fancontrolalgorithm
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