Technical Note.docx

Auto Changeover along with Synch Facility Constant commitment: Critical applications require a constant and reliable power supply to keep fundamental services running and prevent serious consequences due to interruption or absence of the electrical grid or plant tripped. This need is even stronger nowadays because of the increasing significance of key role, capacity and features of these systems. Necessary for uninterrupted electrical supply: If your power plant requires constant electricity to maintain critical services, then an auto changeover along with Synch Facility is your best option, especially if your services represent the financial interests or general safety of other parties. Some common examples of entities that implement automatic switches out of necessity are: power plant auxiliary load, hospitals, data centres, jails and prisons, fire departments, defence organizations, and police departments. Advantage of Auto Changeover along with Synch Facility over High speed transfer switch: Although high speed transfer switches can perform the job to transfer the auxiliary load of the plant from one source of electricity to another one very well but the working principle of these switches is open transition, i.e. Break-before-make. In that scenario there is chance of interruption in the plant not all the time but can happen some times. So that auto changeover switching system along with synchronization facility is better and reliable instead of high speed transfer switch. In that system changeover of the auxiliary load of the plant can be transfer smooth all the time and there will not be any chance of interruption because of its working principle close transition make-before-break. Ideal for efficiently switching to generator power: Beyond the necessity of maintaining constant electrical supply, an auto changeover switching system along with synchronization facility offer the most efficient way to change from utility feed to generator feed. Instead of locating manual switches after the lights go out, businesses can let the changeover happen automatically, the only scenario that wholly exempts a building from the noticeable effects of a power outage, allowing the business to carry on as before. Needs less maintenance than a high speed transfer switch: Auto changeover system typically involve less maintenance because they involve less complex components, particularly in terms of testing maintenance and replacement parts. Requirement of FEL:

FEL has 02 Nos. 6.3 kV incoming buses and 01 No. 6.3 kV common bus (Refer Drawing No. 711FC01081S-D0102-02).

Normally the power is imported from the National Grid for Unit start up i.e. the breakers A, B and D are closed for the import of Power from National Grid (start one unit at a time). After synchronizing the unit, it is required to utilize FEL own generated power for the auxiliaries of second Unit by closing the 6.3 kV Breakers E and F by disabling the HCO (installed at E&F). The 2nd unit will be synchronized with the National Grid by closing the breakers H, I and J. At this moment it is required that auxiliaries load should be put on their dedicated unit through an auto transfer switch i.e. closing of Breaker G and opening of Breaker F (and similar will be the case with the breakers D and E). Solution:

Proposal for Auto Changeover along with Synch Facility

11kV/6.3kV

11kV/6.3kV

D (MB)

G (MB) Common bus

Bus-1

E (GB)

C.T signals F (GB)

AGC-4

Bus-2

AGC-4

Required signals and control (breaker D & E ) As per provided drawing (Refer drawing no. 711-FC01081SD0102-02) 1234567-

ON/OFF control of breaker D Normally open contact point of breaker D ON/OFF control of breaker E Normally open contact point of breaker E Breaker D incoming side P.T signals(100/110V) 6.3Kv common bus P.T signals(100/110V) C.T signals between breaker D and E (Bus-1)

Required signals and control (F & G) As per provided drawing (Refer drawing no. 711-FC01081SD0102-02) 1234567-

ON/OFF control of breaker F Normally open contact point of breaker F ON/OFF control of breaker G Normally open contact point of breaker G Breaker G incoming side P.T signals(100/110V) 6.3Kv common bus P.T signals(100/110V) C.T signals between breaker F and G(Bus-2)

Change over operation & procedure for breaker D & E We will use Deif multiline-2 AGC-4 controller for this operation. There will be two modes of operation 1-Manual mode 2-Auto mode

Manual mode In manual mode there will be options to synchronize any breaker (D or E) by selecting it (Breaker D close) or (Breaker E close) through selector switch 1S1 or 1S2

The opening operation of breakers (G or F) will be also selectable by 1S1 or 2S2 There will be option of both breaker (D and E) synchronized operation at same time in manual mode

Auto Mode As per provided information If 6.3kV common bus is energized through closing of breakers (F, G, H) or (F, G, I, J) At this moment If operation mode is selected to auto through selector switch (1S3) then, Breaker ( E ) will be closed automatically to energise the bus-1 for start up of G-1 after checking the voltage and frequency After the start up of G-1, when voltage and frequency is ok at Breaker D incoming bus (6.3Kv) At this moment breaker (D) will be synchronized automatically with bus and breaker (E) will be open in selected time or immediately and load transfer operation will be completed between breaker D & E

Note Same signals and control will be required for load transfer and synchronization of breaker F & G.