Answer / u.v.v.satyanarayana

dol is a direct on line starter means less than 5h.p
machines consists of roughed construction so resistance is
high.so there is no use of starting current limiting.
but in case of high rating motors starters
necessaty.

Answer / anandh

The motor will draw a high starting current until it has run up to full speed. This starting current is commonly around six times the full load current.To reduce the inrush current, larger motors will have reduced-voltage starters or variable speed drives in order to minimise voltage dips to the power supply.

DOL starters uses upto 5 HP motors.Star/Delta starters uses at above 5 HP motors.

DOL starter starts the motor in directly at on line.But Star delta starter starts the motor at directly and works at star and after 5 sec works at delta .

What is the effect of atmospheric pressure & Temp; on efficiency of motor? Why NGR(Neutral Grounding Resistor) is used in 132/11 KV Transformer & how? What is the use of Auto T/F in Grid Station?

0 Answers   K-Electric Limited,

---

what is the difference between "ampere trip and ampere frame"

1 Answers  

---

why there is no short circuit when any resistance is used between phase and neutral?

3 Answers  

---

What is the Ramping rate of Generator. What mena Ramping rate

2 Answers   Siemens,

---

Hi, I'm running plastic reprocessing company where all motors are running only in delta. Due to that when I use start my 30 hp motor my transformer gets fuse. Where it happens two times a day. I gt a suggestion from a person about Automatic Power Factor Controller APFC. Is it useful for my problem??? Or is der any other way for solving this problem?? Upgrading the transformer is difficult. Pls give Me ur suggestion. Waiting for ur reply.

2 Answers   Shree Lingaa Polymer,

---

AMF (auto mains failure) control for DG sets at home.

1 Answers  

---

how to identify small motor and generator?

1 Answers  

---

Define coil span?

0 Answers  

---

What is thermal relay and how it is works in transformer please explain

2 Answers   Future Group,

---

what is the safe meggar values for motor, transformer HT, LT and Cables? IF we want to replace I/C bay at our 220 kv substation which is of 140 mw load capacity bay to be replaced by 400 mw capacity bay.other than CT(1200/1) what are the other equipment i have to replace. why we generally use 3.5 core cable or in other word 1/2 core for neutral and also confirm me that in balance conditiob(3 phase)current in neutral will zero

0 Answers   Jindal,

---

What is emperical relation.Name few of them which are used in electriacl engineering?

1 Answers  

---

in star-delta tranformer,if the input of star connection is 400/7v 3 kva then what is the output of delta connection?

0 Answers   Elicon,

---