1. What is the formula for width of the tank for single phase transformers used?
a) width of tank = 2*distance between adjacent limbs + external diameter of h.v windings + 2*clearance between h.v windings and tank
b) width of tank = distance between adjacent limbs + external diameter of h.v windings + 2*clearance between h.v windings and tank
c) width of tank = 2*distance between adjacent limbs * external diameter of h.v windings + 2*clearance between h.v windings and tank
d) width of tank = distance between adjacent limbs * external diameter of h.v windings + 2*clearance between h.v windings and tank
Explanation: Width of tank = 2*distance between adjacent limbs + external diameter of h.v windings + 2*clearance between h.v windings and tank is the formula for three phase transformer. For single phase transformers, the distance between adjacent limbs is not multiplied.
2. What is the formula for the length of the tank?
a) length of the tank = external diameter of h.v winding + clearance on each side between the winding and tank along the width
b) length of the tank = external diameter of h.v winding * clearance on each side between the winding and tank along the width
c) length of the tank = external diameter of h.v winding + 2*clearance on each side between the winding and tank along the width
d) length of the tank = external diameter of h.v winding / 2*clearance on each side between the winding and tank along the width
Explanation: The external diameter of h.v winding is obtained. Next, the clearance on each side between the winding and tank along the width is calculated and is substituted in the above formula.
3. What is the formula for the height of transformer tank?
a) height of transformer tank = Height of transformer frame + clearance height between the assembled transformer and tank
b) height of transformer tank = Height of transformer frame * clearance height between the assembled transformer and tank
c) height of transformer tank = Height of transformer frame/clearance height between the assembled transformer and tank
d) height of transformer tank = Height of transformer frame – clearance height between the assembled transformer and tank
Explanation: Firstly, the height of the transformer frame is calculated. Next, the clearance height between the assembled transformer and tank is also calculated. Substitute the values to obtain the height of transformer tank.
4. What is the rating of the transformer for the voltage of about 11 kV?
a) 1000-2000 kVA
b) 100-3000 kVA
c) 1000-5000 kVA
d) 100-500 kVA
Explanation: The minimum value of the rating of the transformer for a voltage of about 11 kV should be 1000 kVA. The maximum value of the rating of the transformer for a voltage of about 11 kV should be about 5000 kVA.
5. What is the rating of the transformer for the voltage of above 11 kV upto 33 kV?
a) 1000-5000 kVA
b) less than 1000 kVA
c) above 1000 kVA
d) 100-500 kVA
Explanation: 1000-5000 kVA is the rating of the transformer for the voltage of about 11 kV. When the voltage rating is about 11-33 kV, then the rating of the transformer is less than 1000 kVA.
6. What is the formula for the diameter of the single phase core type transformer?
a) D = diameter of circumscribing circle + Width of window
b) D = diameter of circumscribing circle – Width of window
c) D = diameter of circumscribing circle * Width of window
d) D = diameter of circumscribing circle / Width of window
Explanation: First the diameter of the circumscribing circle is obtained. Next, the width of the window is calculated, and the sum of both the data provides the diameter of the single phase core transformer.
7. What is the formula for height of the single phase core type transformer?
a) height = height of the window – height of the yoke
b) height = height of the window + height of the yoke
c) height = height of the window – (2*height of the yoke)
d) height = height of the window + (2*height of the yoke)
Explanation: The height of the window is first obtained. Next, the height of the yoke is calculated and it is multiplied by 2. Addition of both the values gives the height of the single phase core type transformer.
8. What is the formula for width of the single phase core type transformer?
a) width = Width of largest stamping / Diameter of the transformer
b) width = Width of largest stamping + Diameter of the transformer
c) width = Width of largest stamping – Diameter of the transformer
d) width = Width of largest stamping * Diameter of the transformer
Explanation: Firstly, the width of the largest stamping is calculated. Next, the diameter of the transformer is calculated and the sum of both the values gives the width of the transformer.
9. What is the formula for the width over 2 limbs?
a) width = Width of largest stamping + Diameter of the transformer
b) width = Diameter + outer diameter of hv windings
c) width = Diameter – outer diameter of hv windings
d) width = outer diameter of hv windings
Explanation: width = outer diameter of hv windings is the width over one limb. width = Width of largest stamping + Diameter of the transformer is the formula for width of the transformer
10. The formula for single phase core type and three phase core type diameter and height are same.
a) true
b) false
Explanation: D = diameter of circumscribing circle + Width of window is the diameter of single phase and 3 phase core type transformers. height = height of the window + (2*height of the yoke) is the height of the single and three phase core type transformers.