CN203396890U

CN203396890U - Disconnection alarm for digital input signals

Info

Publication number: CN203396890U
Application number: CN201320503962.XU
Authority: CN
Inventors: 沙明; 文敏哲
Original assignee: Northeast Electric Power Design Institute of China Power Engineering Consulting Group
Current assignee: Northeast Electric Power Design Institute of China Power Engineering Consulting Group
Priority date: 2013-08-19
Filing date: 2013-08-19
Publication date: 2014-01-15
Anticipated expiration: 2023-08-19

Abstract

The utility model relates to a disconnection alarm for digital input signals. The alarm comprises a DCS or PLC cabinet, cables or leads, and a digital input switch; and is characterized in that a resistor is connected in parallel with the grounding side of the digital input switch. During normal operation of the alarm, if the digital input signals are normal and contacts are opened, a DCS or PLC can detect relatively low current due to the resistor connected in parallel to the ground, and the digital input signals are represented as 0; and if the digital input signals are normal and the contacts are closed, the DCS or PLC can detect relatively high current even though the resistor is connected to the ground in parallel due to the fact that to close the contacts is equivalent to short the resistor, and the digital input signals are represented as 1. When the cables or leads are disconnected, no matter the digital input signals are in on or off states, the DCS or PLC does not detect current, and the DCS or PLC emit disconnection alarm on a display to notify an operator, so that the operator or maintenance staff can detect the cables or leads, thereby eliminating faults in real time, and avoiding occurrence of serious accidents or economic loss.

Description

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.

Claims

1. a 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.