Answer / bimal ch b orah

onan means oil natural air natural
onaf means oil natural air forced
ofaf maens oil forced air forced
DYN primary is connected in delta and secondary is
connected in star

Answer / pillay

Answers #1 & #2 is correct but i can add something for the the benefit of some.
In ONAN the oil in the TX former circulates on its own due to hot oil goes up & cooler oil goes down.The TX former is cooled by just the air around it.
In ONAF the oil circulates as above but a fan is used to cool it.
In OFAF the oil is pumped with a pump for circulation and the air is cooled by a fan.
In DYN the primary winding of the tx former is wound in delta and the secondary is wound in star with tapping for neutral connection.

Answer / zahid

onan means oil natural air natural
onaf means oil natural air forced
ofaf maens oil forced air forced
DYN primary is connected in delta and seconday is connected
in star with neutral

as we see that in our country the power rating for transmission is always rated in multiple of 11 like 11kv,33kv,66kv132kv. So i want to know wht is reason or logic here.

2 Answers  

---

How to calculat the size of copper& aluminium wire ?

5 Answers   Hindalco, IOCL,

---

Which one is easy to control AC or DC Machine?

2 Answers   BARC,

---

What is reverse power relay?

0 Answers  

---

Brief use of isolation transformer & how it works.

1 Answers  

---

what is diffrent of RCCB & MCCB

6 Answers  

---

What does “battery of 180 AMP HOUR” mean to you?

2 Answers  

---

What is the range of the stator resistance of 3 phase induction motor?

0 Answers  

---

Why neutral grounding Transformer provided for generator?

1 Answers   Siemens,

---

What is the difference between a 3 winding and 2 winding Potential Transformer

0 Answers   Engineers India,

---

What is working principal of V.C.B., O.C.B., A.C.B & Over load relay?

4 Answers   Unitech,

---

why we avoid parallel operation of diesl generator?

4 Answers  

---