Cascade start of hoods

Sequential start-up unit of the “CASCAD” equipment

The software part

To reduce the starting loads when a large number of equipment is turned on at the production site, the CASCAD function block is used - this is a block of sequential equipment start-up.

The unit processes the input values of the states of the monitored equipment and generates a sequential output of pulses to the discrete outputs of the unit, which are transmitted to the equipment control algorithms for the formation of automatic A_START commands. If the control algorithm (for example, a fan) receives an impulse from the cascade start-up unit of the equipment, then the algorithm begins to run (fan start-up). The location of the black inputs and outputs is divided into three groups, so, for example, IN 1 corresponds to OUT 1, etc. If all digital inputs are activated (TRUE), then the pulses to the output channels of the function block do not pass.

The unit supports the ability to supply additional pulses to those pieces of equipment that, for one reason or another, could not turn on immediately. At the same time, if the algorithm to which the A_START pulse is applied gets the opportunity to start the owned equipment (automatic mode and there is no blocking), the equipment turns on.

The logic of the functional block allows you to change the time range between hardware startup attempts, which is set at the input of the block (WAITING). This delay time is allowed only if there are no input states (IN1...10 – FALSE), if any digital input is active, then there is no delay on it. The function block skips this step without sending an impulse to the corresponding output, but proceeds to the next step. Thus, the delay (WAITING) acts exclusively on equipment that has not yet been turned on. The pulse duration is set statically and is 2 seconds. The selection output signal is designed to monitor the transient states of this unit. If the output takes the value "2", then the step IN1 – OUT1 is performed, if "7", then IN6 – OUT6, etc. The function block is protected from the possibility of sending two or more commands simultaneously, which makes the equipment safe to start. If the INITIAL input channel is deactivated (FALSE), the function block stops processing its discrete output data.

Assignment of inputs and outputs of the function block

Application Features

The cascade start function block can be used in a fairly wide range of automation industries. Its main distinguishing feature is the supply of pulse commands to start devices in algorithms that are equipped with self-interception circuits.

Recommendations for use

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