which stabilizer is better ? AVR, Servo Stabilizer, Static stabilizer etc & why explain it

if we want to convert the two 12 V DC batteries in parallel for UPS ? what would be the result ? which is better for a UPS , connect two batteries in series or connect them in parallel ?

what is the formula for converting KW into KWH ?

Blue Star, Essar,

why dont we connect the two 12 V DC batteries in parallel, for an inverter (UPS)? is there any harm ?

will we have to design the UPS differently for both i.e. if we want to connect the two batteries in parallel and/or we want to connect the two batteries in series ?

When we design PI controller, when we design PID controller & is there any ID controller ? When we design PI controller, when we design PID controller & is there any ID controller ? Explain the working of Incubator Box which is a PI controller ?

What is SCADA ? What are its main components ? How it works ? When we need a SCADA & where ? Is there any similarities and comparison b/w PLC & SCADA ? What are its Pros & Cons ? What are the faults that occur in it most ?

when & where we say that here communication electronics gets involve ? Difference b/w communication electronics, power electronics, digital electronics, discrete electronics, analogue electronics & Mechatronics ? Where these are used & can be used ?

What is PLC ? What it does ? What are its components ? When & where we use PLC & How ? What are its Pros & Cons over other things ? What are the main faults that occur in it ? What are other devices that are similar to it and how we can compare them all ?

Pricol,

what are the main problems that happen in an emergency light and how to fix them ?

What should be the values of settling time, peak time, steady state error, overshoot, rise time, MPOS (Maximum percent over shoot) to keep the system in transient state, to keep the system in steady state ?

Do these factors (settling time, peak time, steady state error, overshoot, rise time, MPOS (Maximum percent over shoot)) are the part of first order, second order, higher order, linear, non-linear, open-loop, closed-loop, homogeneous & non-homogeneous systems ?

Limton,

What is state space method ? Why its used ? Can it applicable on linear, non-linear, 1st order, higher order, homogeneous, non-homogeneous, open-loop , closed loops , stable & unstable systems ?

Limton,

What are merits & De-merits of State-Space Method? What is series programming, parallel programming, general programming & direct programming ? And, difference between these programmings Techniques ?

In what cases (circumstances)we should apply P controller, PD controller, PI controller & PID controller ?