EXHAUST - algorithm PLC for control big quantity of equipment

Fan control unit with speed controller "EXHAUST".

The software part

It is used to control the discrete relay output of the fan, as well as the analog output for solving the problem of speed control - the EXHAUST function block.

Processes the input values ​​of the process and generates the output of discrete and analog signals needed to control the fan with a speed controller. The operation of the fan at a reduced speed is not a characteristic task, leading to its overheating, for this the function block has protection from issuing an executive command to the variator below 20%. The fan speed regulator requires a gentle supply of the executive command (SPEED), in this connection the unit has the function of smoothing the output value, in order to avoid sharp jerks during the on or off of the fan motor. Discrete violations of ALARM1 (fan belt break), ALARM2 (malfunction of the variator), ALARM3 (unreliable status) are generated only after the fan is turned on, and reset if there are no reasons for causing them and restarting the unit. If a new violation occurs, the discrete output of the block (OUT) is reset, which causes the equipment associated with it to stop. The unit provides protection against the possibility of frequent on-off operations by the operator. This means that the operator does not have the ability, once turning off the fan to turn it on immediately after turning it off, it is required to wait at least 20 seconds, after that the permission to turn on the fan appears.


Assignment of inputs and outputs of the function block

Input: Type Value Output: Type Value
STATUS BOOL Status FAN OUT BOOL Command on the variator relay
IMPSPD BOOL Belt State SPEED REAL Analog output to the fan variator
INTRLK BOOL Interlock ALARM1 BOOL Slippage of the fan belt
CMD REAL Distand command ALARM2 BOOL Unreliable state of the fan
A_STRT BOOL Local start ALARM3 BOOL Faulty CVT
A_STP BOOL Local stop
DEAD_FRIQ BOOL Friquency health


START BOOL Local start

STOP BOOL Local stop


Application features

This function block can be used with any motorized devices that have a speed controller.

Recommendations for use


The analog output from the block is transferred to the block for translating the field values, and then it is transferred to the analog output 0-20 mA. The analog input channel CMD is assigned to the output of the PID function block.

#EXHAUST, #fancontrolunit, #fancontrol, #control, #speedcontrol, #control, #functionblock, #PID

Russian version

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