Switching value input signal wire break alarm
Technical field
The utility model relates to fuel-burning power plant thermal switch amount input wire break alarm.
Background technology
In thermal power plant, the open and close state of switching value input signal general proxy valve; The startup of motor, halted state; Parameter reaches a certain limit value etc.DCS system or PLC system be according to switching value input signal and other signals, according to logical condition output signal opertaing device or warning in case power plant constantly in safety and economical operation.Switching value input signal is in total IO(input and output of the DCS of thermal power plant system or PLC system) ratio of counting is larger.Whether switching value input signal reliably directly affects safety and the economical operation of thermal power plant.
Common switching value signal is all passive normally opened contact.When DCS system or PLC system are normally moved, may cause contact close signal not to be identified because cable break, cable inside conductor broken string or connection terminal get loose, cause DCS system or the tripping of PLC system and cause major accident or economic loss.
Utility model content
The purpose of this utility model is to provide a kind of instrument of new detector switch amount input signal, improves thermal process automation of fossil power plant level.
For achieving the above object, the utility model provides a kind of switching value input signal wire break alarm, comprises DCS or PLC rack, cable or wire, switching value input switch, it is characterized in that: at a side the connecting resistance on the spot of switching value input switch.
When the utility model normally moves, if switching value input signal is normal, contact disconnects, and due on the spot and the resistance being connected to, DCS/PLC can detect less electric current, and representation switch amount input signal is " 0 "; If switching value input signal is normal, junction closure, although on the spot and the resistance being connected to, because junction closure is equivalent to resistive short, DCS/PLC can detect larger electric current, representation switch amount input signal is " 1 "; When cable or wire breaks, no matter switching value input signal is to disconnect or closure, DCS/PLC will can't detect electric current, DCS/PLC sends break alarm notice substation operator on display, operation and maintainer can check cable or wire, fix a breakdown in time, avoid the generation of major accident or economic loss.
Accompanying drawing explanation
Accompanying drawing 1 is the utility model structural representation.
1-DCS or PLC rack;
2-cable or wire;
3-switching value input switch;
4-resistance.
Embodiment
With reference to accompanying drawing 1, at a side on the spot the connecting resistance 4 of switching value input switch 3.When the software configuration of DCS or PLC rack 1, to and the resistance switch amount input signal that connects break alarm function is set.When the cable or wire 2 of a certain switching value input signal breaks, on DCS HuoPLC host computer operator station picture, can send warning, remind operation and maintainer to check cable or wire, fix a breakdown in time.
As to adopt the utility model, financial cost be low-down.The price of each resistance only has several units, adds 50 yuan only of erected costs.1 the 600MW fired power generating unit of take is example; total IO approximately 6000 points of counting; wherein switching value input is about 2300 points; if all adopt the utility model; 11.5 ten thousand yuan only of overall costs, and because cable or wire broken string causes DCS or PLC tripping, and then the thermal power plant's accident causing or shutdown loss will be over hundreds thousand of so that more than 1,000,000; so the utility model has improved security and the economy of power plant, is applied and promotes in big-and-middle-sized thermal power plant.