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Which is correct, in the given below power triangle with respect to the power vectors if vector b is active power?

2.Which is correct, in the given below power triangle with respect to the power vectors if vector b is active power?

(a) a: kVAr b: kVA c: kW

(b) a: kW b: kVA c:kVAr

(c) a: kVAr b: kW c: kVA

(d) a: kVA b: kW c:kVAr

Ans:c

3.What is the preferred OLR setting range for a 22.5 kw , 415V , 3 Phase SCIM motor , Y/D starter , against over loads in amperes ?
a. 9 – 15
b. 20 – 33
c. 14 – 23
d. 30 – 50
Ans: b
Given data :-
Power =22.5KWor22.5\times10^3W
Voltage = 415 V
Required data :-
OLR Current setting = ?
Solution:-

P=\surd3V_L\times I_L\times cos\theta
Power factor is not given in this question  so we can assume 1 or unity
P=\surd3V_L\times I_L\times cos\theta

\begin{array}{l}\rightarrow\;22.5\times10^3=\surd3\times415\times I_l\times1\\\end{array}

\begin{array}{l}\rightarrow I_l=\frac{22.5\times10^3}{\sqrt3\;\times415}\\\end{array}

= 31.30A [ Full load current ]

We know that each thermal over load relay current should be set is 80% full load current of the motor .

→ OLR current =(80/100)×31.30

= 25.04A

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