Answer Posted / prakesh kumar

MCB mean "Main Circuit Breaker", meaning the primary
circuit breaker in a group or panelboard / switchboard. In
IEC world, it means "Miniature Circuit Breaker", typically
a DIN rail mounted circuit breaker in a small format that
is limited to 100A, and is intended for use in
installations with low fault current capacity (under 25kA)
unless protected by upstream fuses. In NEMA world, these
devices entered under special rules adopted by UL (UL1077)
and are called "Supplementary Circuit Protectors" because
they did not meet the criteria already established
for "circuit breakers" under UL489. In recent years, many
manufacturers have come out with special versions that do
now meet the UL489 standards for circuit breakers, so the
term MCB has taken on a dual meaning. So in NEMA world, the
acronym MCB now has contextual relevance. MCBs /
Supplementary Circuit Protectors are sealed units that can
be neither maintained or repaired, they are throw-away
devices.

MCCB Was originally an IEC term meaning Molded Case Circuit
Breaker, but has been very well adopted in NEMA world now,
at least at the engineering level. Many rank and file
electricians still are not familiar with that acronym
because its widespread use in NEMA world is fairly recent.
MCCBs generally range from 15A to 1600A, with a few
exceptions at either end, and generally start at 14kAIC but
go up to 100kAIC for applications with high fault current
capacity. There are versions that are Current Limiting (CL)
as well. MCCBs are typically sealed units and cannot be
serviced, although in larger sizes there are versions with
interchangeable parts that can be replaced such as trip
units and switch bodies.

hi Is there any possibilities to find out the rotation of a shaft or something else by using electromagnectic waves or by IR rays.If s then can v change the dir., of rotation of the same by remotely?& how? plz dn't any1 say "NO r CAN'T"

2030

---

working principle of AC Servo Motor with its construction

8831

---

i want design of D.C.MOTOR 1HP 960RPM AND 2HP 960RPM ITS URRGENT

1891

---

What is the dc grounding system and what is diff between AC/DC grounding system?

2051

---

What are the specifications for getting approval of Substation?

1870

---

how to calculate IR value of 33KV cable ??

1817

---

what is data block in plc ? How the values of data block are written and read by hmi ? what is the difference between function and function block ?

3371

---

ASTM D 3455 - Standard Test Methods for Compatibility of Construction Material with Electrical Insulating Oil of Petroleum Origin has been used for Testing Transformer Oils with a product placed in it. Aged Control Oil has a Power Factor of 0.032% at 100°C. Aged Oil with a Test component has a Power Factor of 0.093% at 100°. Is this increase acceptable? If not why? How much increase is acceptable?

1963

---

Could the power factor on electrical system can affect the registration of the kwhr meter or the CT/PT? 

1892

---

how flow current in 220 kv line to line

1918

---

What is 11 N1 and 12 N2 in single phase Transformer ?

1873

---

we have earthmat at 110KV substation.we would like to take earth resistance.b some says that by connecting earth megger terminals (C1,P1) at middile point of earthmat (at riser) will cause voltage gradient at other earthmat nods and dont get exat earth resistance.when connecting at end nods will get exat value . is it correct .please explain

2168

---

What is the effect on 3phase induction motor if current setting knob of DOL kept at minimum current?

3662

---

Dear all, I want to use Induction motor to open and close a 1 ton door. How much power do I need. Thanks

1826

---

How to calculate VCB rating for 33KV ,25 MW Power line?

1695

---