Answer / brakadeesh

motor rating 75kw,so it taken full load p=1.732*v*I*cosfy
i= p/1.732*v*cosfy
=123 amp. so we requared a cable to carry 123 amp
contonious rating. so require to run motor in star delta
starter . in star delta connection load current is 58% of
line current. we require 58% of 123 amp carring capasity
cable.it is around 71 amp.generly copper cable taking 4
times current of cable rating and alluminium cable taken
1.5 times of cable ratting .so for 71 amp carring alu.
cable 50mm2 suffisent but due to high starting curent its
take 70 mm2 cable ib best.
its overload relay ratting is in range to 71 amp. it to be
60-80 amp,and mccb rating is 2.5 times of full load =200
amp
is best.

Answer / pvr.parthasarathi

75 Kw motor takes 134 amps full load current. But for
selecting its Cable, Contactor, OLR and MCCB, we have to
consider many other factors such as need of its operation.
Place of the Motor Control Centre and possibility of laying
the cable Wheter inside the duct, underground or in the
air. For selection of the Contactor enclosure of the
panel, its environments etc are to be taken into
consideration. So giving answer at a stretch basing on
some thumb rule is not technically qualified.

Other particulars are required.

Answer / v.raguvaran

THE MOTOR AMP IS 130AMP.THE CABLE(USE COPPER ) SIZE SHOULD BE 45sq.mm (delta connection),35sq.mm(star delta)
OLR RATING IS (125-135) BUT STANDARD SIZE IS (130-175)ABB
CONTACTOR RATING IS 200A(DELTA),100(MAIN)-100(DELTA)-50(STAR)
MCCB RATING IS 250A

Answer / mohamed-mohamed

i know> but my nglish not well> because of that i can not answer

Answer / rsbangra

motor rating 75kw,so it taken full load p=1.732*v*I*cosfy
i= p/1.732*v*cosfy
=123 amp. so we requared a cable to carry 123 amp
contonious rating. so require to run motor in star delta
starter . in star delta connection load current is 58% of
line current. we require 58% of 123 amp carring capasity
cable.it is around 71 amp.generly copper cable taking 4
times current of cable rating and alluminium cable taken
1.5 times of cable ratting .so for 71 amp carring alu.
cable 50mm2 suffisent but due to high starting curent its
take 70 mm2 cable ib best.
its overload relay ratting is in range to 71 amp. it to be
60-80 amp,and mccb rating is 2.5 times of full load =300amp
is best.

in three 3.5 core aluminium ug cable. one cable is used for one phase by shrting R,Y and B wires and other 2 cables used for Y and b phases. balace 3 neutral wires are made common and connected to load. suddenly neutral current was more than line current what is the reason behind this?

1 Answers   DLF,

---

WHAT INSTRUMENT IS USED TO MEASURE THE MAGNETIC FLUX?

7 Answers  

---

Is it benefitial to supply 210v ac to lighting fixtures instead of 240v ac?

2 Answers  

---

What is the difference between single core 2 wire and single core 3 wire system? Which application we are using this? and for What purpose we are using this?

0 Answers  

---

Thermal withstand capability under full short circuit conditions, in terms of number of times of occurrence of short circuit and corresponding anticipated percentage reduction in transformer life.

0 Answers  

---

---

Why no-load primary current is very small as compared to full load current in transformer (as 1% of full load current?

5 Answers   NTPC,

---

How many methods use the load flow solution?

0 Answers  

---

What is the function of PMG in DG sets & how it works??????????

2 Answers  

---

why we use delta connection in transformer

2 Answers   UPPCL,

---

why power factor is lagging and leading(i.e -1to +1)

2 Answers  

---

How to select the different contactors ( starter combination) for different AC motors? what about fuse cappacity 4 different motors too?

2 Answers   Equate,

---

why transformer is rated in kva?

2 Answers  

---