How should I understand the statement that \"after self-protection is activated, it should be immediately switched to local control, and then the self-protection switch should be reset\"?

My understanding is that in the DCS control program, once the feed safety valve activates, an interlock mechanism takes effect, causing the control to switch from automatic to local control. (A safety reset switch is provided on the DCS operation screen; this switch resets automatically once the control mode switches to local control.)

“When the feed self-protection valve activates, an interlock is triggered, and the control mode changes from automatic to local control. How should this sentence be understood? “The self-protection switch resets automatically after the control is changed to local control. The self-protection switch does not reset automatically and requires manual reset.

In my opinion, self-protection is an automatic protective measure that includes actions such as switching on and off certain control valves. Once the self-protection interlock is in place, manual intervention can be used, after which the self-protection mechanism can be reset to prevent it from activating again due to improper human operation.

The feed is controlled by a safety valve; only the misting steam control valve is set to its maximum setting, with the only other valves being the two safety valves on the raw material line. After the feed auto-start is activated, it cannot be reset, and the atomizing steam control valve also cannot be switched to local control.

Self-protection is basically no longer necessary; we have removed it in our systems. However, from a security perspective, it is still advisable to use V, as there is a concern that its use might lead to deviations or other abnormal situations.

Yeah, even for self-protection during feeding, it doesn’t use automation. But sometimes, feed self-protection is enabled manually.

This post was last edited by *aojiaoya0546 on 2015-8-3 at 18:30. How should we understand the statement \"After self-protection is activated, it should be immediately switched to local control, and then the self-protection switch should be reset\"? Interlock self-protection – it is a safety mechanism that cuts off the power supply to the solenoid valve; in the event of a power loss to the solenoid valve, the self-protection valve will automatically open or close completely ； Control must be established on-site now: set the control valve to manual mode, and open or close the valve to the position at which the safety valve operates, so that the set value of the control valve matches the position of the safety valve ； Self-protection switch reset: This involves supplying power to the solenoid valve, at which point the valve position will match the set value specified by the DCS ； In summary: once automatic protection is activated, it should be immediately switched to local control, and then the automatic protection switch should be reset, with the aim of keeping the device in a safe state during emergency situations.

Once the automatic feed protection system is in use, it’s necessary to switch all three slide valves to manual mode for shutdown (it is highly recommended to rely on manual shutdown at the site; we encountered some minor issues here). If the opening degree of the regeneration slide valve during normal operation is 35%, when the safety function is activated, it does not switch to manual mode nor is the output set to 0; instead, the valve is forced to close manually on-site. After the safety function is reset, the regeneration slide valve will open to a certain degree – generally, it won’t reach 35% due to loss of tracking capability. But this is not what you want; what you desire is for the valve to open gradually, thereby establishing a catalyst circulation.

“It should be changed immediately to local control – this has nothing to do with automatic protection, right? For example, in the case of accident steam in the catalytic main air automatic protection system, after the automatic protection interlock activates, the manual valve stops the accident steam; once the on-site handling is completed, the automatic protection is reset

There is no direct relationship, but there is an indirect one! It is to ensure that the valve remains in a safe state after self-resetting!