If no load is connected to solar PV system,

At no load the solar cell will be operating in open circuit condition.
If there is internal shunting resistance it will slightly load the solar cell.
This shunt resistance must be high enough such that it will not cause an appreciable loss of the photo voltaic power.

The necessary equation to be solved during the load flow analysis using Fast-Decoupled method is given below:
where B' and B'' are formed using the imaginary part of the bus admittance matrix, Ybus. If the system consists of 6 buses of which one of the bus is slack bus and 2 bues are voltage regulated buses, then then the matrix B' is of order ____and the matrix B'' is of order____, respectivity.
∆P/|Vi| = - B'∆δ
∆Q/|Vi| = - B''∆|V|

In Fast-decoupled method,
Order of B' = No. of PV buses = 5

Order of B'' = No. of PQ buses = 3

If all the devices are connected to a central hub, then the topology is called

The voltage applied to a transformer primary is increased keeping V/f constant. With this, the core loss ____ and the magnetizing current (Im) ____

For trasnformer:
1. e = 4.44fφ*Turns
2. V/f ≈ e/f ∝ φ ∝ B
3. Eddy Current loss, Pe ∝ B²f² ∝ f² (as B is constant if V/f is constant)
4. Hysteresis loss, Ph ∝ B^1.6*f ∝ f
If V/f is constant, B is constant, mmf required to create B is constant, Im is constant.

In a 3-phase, 4-wire, 400/230 V system, a lamp (L1) of 100 W is connected to one phase and neutral and a lamp (L2) of 150 W is connected to the second pahse and neutral. If the neutral wire is disconnected accidently, then

When neutral disconnected, lamps are in series connection,
So, for series connection current is same for both Lamp,
So, Resistance of 100 W Lamp is more compared to 150 W Lamp.
Hence after neutral connection disconnect 100 W Lamp is more brighter than the 150 W Lamp.

A coil having an inductance of 100 mH is magnetically coupled to another coil having an inductance of 900 mH. The coefficient of coupling between the coils is 0.45. Calculate the equivalent inductance if the two coils are connected in series opposing.

M = k√(L₁L₂)
M= 0.45√(100*900)
M = 135 mH

L_eq for opposite connection of coils = L₁ + L₂ - 2M
L_eq = 900 + 100 - 2*135
L_eq = 730 mH