The S7 300 PLC inherits the traditional design features of Siemens S series PLC with small size, flexible configuration and powerful functions. It is very suitable for the accuracy, reliability and completeness of the thermal protection device.
OP5 Operator Panel The operator panel is a convenient and practical man-machine dialogue device manufactured by Siemens. It is mainly used to display and monitor the internal information of the programmable controller PLC, and set the PLC internal parameters through the function keys on the panel. The main displayed contents are: event information and alarm information. The alarm information is displayed with a higher priority than the event information. If the condition of an alarm message is satisfied, the display of any event information will be replaced by the flashing alarm information.
The SIMATIC programmable controller provides a rich and convenient interface for the OP. The OP can be directly connected to the Siemens S7 series PLC to realize the man-machine alignment of the control process, or it can be set offline. The current OP series has: 1 text display device, its process variables can be numerically displayed, or related symbols, and its functions and interfaces are defined by the programming tool software COROSProtool/Lite in the MSWindows environment; o-shaped display device Use COROSProtool to define its functions and interfaces. Protool programmers can use familiar Windows-shaped software such as Design-er, CorelDraw, Paintbrush, etc. for graphic design. These static shapes will be input into the process display in Bitmap format, such as: bar curve, process flow, etc. The ground is displayed.
According to the requirements of the unit control system of Shentou No.1 Power Plant, the OP5 operator panel is designed with the following main functions: automatic tour scroll display; manual single screen display function; alarm display function; protection cast and retract function; system setting function; System reset function; password protection function.
System logic function and working principle protection system over-limits the important thermal parameters of the furnace, and issues a forecast or protection switch signal according to the over-limit condition to cause the operator to pay attention or stop. In order to make the protection system work reliably, without false or false signal transmission, the design inherits the signal processing characteristics of Siemens S series PLC, that is, the measurement signal must be confirmed before the over-limit judgment.
To this end, the signal measurement loop of the same thermal parameter is redundantly configured, and two measurement signals from the program control and the instrument are respectively connected. Here, the input from the program control is referred to as the left input, and the input from the instrument is referred to as the right input. The two input signals are first diagnosed for the validity (fault) of the signal, but only the valid signal may be predicted or protected by the overrun judgment. In the event of a fault, the system outputs a fault status signal to alert the person concerned to quickly troubleshoot.
The working principle and input and output logic of the protection system are as follows:
a. The input signals are first diagnosed separately. The items to be diagnosed are: 1. Whether the signal exceeds the maximum possible range when normal, if it is exceeded, it is considered to be a (range) fault; 2. If the signal exceeds the maximum possible rate of change, If it is exceeded, it is considered to be a (rate) fault; 3. If one of the above two items is generated, it is considered that a measuring circuit has a (channel) fault.
After the above three types of faults occur, their status is maintained and flashed on the operation panel OP5, and the channel fault signal is also output to the centralized control console to remind the relevant personnel to quickly eliminate the fault. The fault message stops flashing only after being acknowledged on OP5, but the fault condition and the moment of its occurrence are still retained in the OP5 buffer for inquiry.
b. When there is a channel failure, the protection output is blocked. The fault status output will be undone only after the fault is removed and the fault reset button is pressed, at the same time the blocking of the protection output is released.
c. After the validity diagnosis, the input signal is judged overrun. The judgment items are: 1. Whether the over-explanation limit is exceeded, if the over-extension is delayed by 2s (or left-right phase/or 0-delay 2s), the forecast signal is output; 2. If the over-protection limit is exceeded, if it exceeds the limit and there is no fault When the lock is blocked, the protection signal is outputted after 2s delay (or left and right phase/2 delay and 2s delay).
d. During the delay of 2s, if the forecast is limited, the delay will be reset; during the delay of 2s, if the protection is closed or blocked, the delay will be reset.
Summary S7 300PLC inherits the traditional design features of Siemens S series PLC with small size, flexible configuration and powerful functions. It is very suitable for the accuracy, reliability and completeness of the thermal protection device. The protection system composed of S7 300PLC, with its program flow programming feature in OB35, strengthens the fault diagnosis logic function and protection logic function of the protection system, especially its protection misoperation rate is greatly reduced, far superior to the original Czech Republic. The module is a mode that protects logic by relay hard wiring.
Guangdong Ojun Technology Co., Ltd. , https://www.ojunconnector.com