NIFPS SYSTEM FOR TRANSFORMER PROTECTION WITH TWO SET OF PLC

Field of the Invention

The present invention relates NIFPS SYSTEM FOR TRANSFORMER PROTECTION WITH TWO SET OF PLC. Wherein one in master control panel & another one in FEC in field In the present system command travel is quicker as the operations are now governed locally from FEC panel. In erstwhile system the signal I command was driven from control panel, thereby the command time taken to operate the valves was higher & also if the cable is cut the system would fail to operate.

Background of the Invention

In the earlier filed patent application, is developed to meet the criteria of failures in order to detect the rise into the temperature of the transformer oil I coolant & thereby taking a feedback of the increase in temperature coupled with the master breaker input to the microprocessor I relay based control circuit & thereby activating the nitrogen purging system by opening the drain valve & injecting the nitrogen gas from bottom of the transformer to stir & cool the oil I coolant through nitrogen release valve as well and bringing down oxygen contents for preventative measures against the explosion and/or resulting in fire in the electrical transformer. i In the above described system, the control supply (power) to the valves - NIV, TCIV & ODV & power to the fire detector unit in SJB is through CP installed in control room. The master panel is equipped with cables & other components required for system activation & operation. In case of system operation the command to the valves installed in field is through the master control panel & post operation I activation of the system the feedback signals for valve operations in field are annunciated in control panel in control room through the cable connection, In case if field cables from CP to FEC, CP to ODV, CP to SJB or CP to TCIV is cut off the system will not operate & hence the very purpose of the system to protect the transformer is defeated. Moreover it may have huge cable cost as well as maintenance/repair cost. Which also creates consequences arising in case of cutting off of any of the power I control cables.

To overcome the said short coming - a modification has been carried out into the system which replace the cable connection with PLC control system.

Object of the invention

The main object of the present invention is elimination of long length of control/ power cables from mater control panel to respective valves & detector unit (in case of Fig. 1). There by saving huge cost as well as eliminating the dreaded consequences arising in case of cutting off of any of the power / control cables. Further object of the present invention system is Localized control from field PLC thus making the system more robust as the command of operation is localized from field itself.

Further object of the present invention is faster operation of the system as decision I system operational logics are all localized at PLC in FEC.

Statement of the Invention

In the present invention system where a master control panel (CP) is located in control room & Fire Extinguishing cubicle (FEC) consisting of Nitrogen cylinder & electrically operated nitrogen purging I injection valve (NIV) is in field near transformer. On the transformer the fire detector panel (Signal Junction Box - SJB) is fixed along with electrically operated transformer conservator isolation valve (TCIV) & electrically operated oil drain valve (ODV).

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings.

Fig.1 represents the system hookup drawing of NIFPS system with single PLC having all the logical controls & command in master control panel installed in control room.

Fig.2 represents the system hookup drawing of NIFPS system with dual PLC one in master control panel & another in FEC panel installed in field. Detailed description of the invention

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and arrangement of parts illustrated in the accompanying drawings. The invention is capable of other embodiments, as depicted in different figures as described above and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation.

Here in both the figures as shown a master control panel (CP) is located in control room & Fire Extinguishing cubicle (FEC) consisting of Nitrogen cylinder & electrically operated nitrogen purging I injection valve (NIV) is in field near transformer. On the transformer the fire detector panel (Signal Junction Box - SJB) is fixed along with electrically operated transformer conservator isolation valve (TCIV) & electrically operated oil drain valve (ODV).

Details of Fig. 1 - In case of Fig. 1 the control supply (power) to the valves - NIV, TCIV & ODV & power to the fire detector unit in SJB is through CP installed in control room. The master panel is equipped with PLC & other components required for system activation & operation. In case of system operation the command to the valves installed in field is through the master control panel & post operation I activation of the system the feedback signals for valve operations in field are annunciated in control panel in control room.

As In case if field cables from CP to FEC, CP to ODV, CP to SJB or CP to TCIV is cut off the system will not operate & hence the very purpose of the system to protect the transformer is defeated. To overcome the said short coming - a modification has been carried out into the system which is reflected in Fig. 2.

Details of Fig. 2 -

In case of Fig. 2 the master control panel & FEC both are equipped with programmable logic controller (PLC). The PLC in FEC is master PLC & hence all the field commands to operate the system are from field itself. The control supply (power) to all the valves including detector unit is from FEC installed in field. The feedback signals for valve operation are also localized in the field.

Advantages of having two sets of PLC (one in master control panel & another one in FEC in field) -

1) Localized control from field PLC thus making the system more robust as the command of operation is localized from field itself.

2) Elimination of long length of control I power cables from master control panel to respective valves & detector unit (in case of Fig. 1). There by saving huge cost as well as eliminating the dreaded consequences arising in case of cutting off of any of the power I control cables.

3) Faster operation of the system as decisions I system operational logics are all localized at PLC in FEC.

While, the invention has been described with respect to the given embodiment, it will be appreciated that many variations, modifications and other applications of the invention may be made. However, it is to be expressly understood that such modifications and adaptations are within the scope of the present invention, as set forth in the following claims.