why transformer rating is expressed in kva.
- 4 Answers
- 8706 Views
- Electrosteel, L&T, I also Faced
- E-Mail Answers
Answer Posted / nitiniitp
kVA is the unit for apparent power. Apparent power consists
of active and reactive power. Active power is the share of
the apparent power which transmits energy from the source
(generator) to the user. Reactive power is the share of the
apparent power which represents a useless oscillation of
energy from the source to the user and back again. It
occurs when on account of some »inertia« in the system
there is a phase shift between voltage and current. This
means that the current does not change polarity synchronous
with the voltage. But the heat generated in a winding as
well as the eddy current losses generated in a transformer
core depend on the current only, regardless of whether it
aligns with the voltage or not. Therefore the heat is
always proportional to the square of the current amplitude,
irrespective of the phase angle (the shift between voltage
and current). So a transformer has to be rated (and
selected) by apparent power.
| Is This Answer Correct ? | 26 Yes | 0 No |
Post New Answer View All Answers
What is FTA card? How it works?
how can see the ac indoor or out door ac which Tr
We have drive feeding an output contactor for a 5000 hp motor @ 5kV application. The motor FLA is 629amps x 1.25% service factor = 786.25 amps The cable that we current have in place between the drive and the output contactor is 350kcmil- MV-105 (parallel cables). Per the NEC table 310.60 (C) (69). This show the cable ampacity is at 615 amps per cable for a rating of 1230 amps. We have derated the cable for the cable tray and the multiple cables application and our calculations show that after the correction factor factor we are at 922amps. 1230 amps x .75% correction factor factor = 922.5 amps. The customer is driving us to then use another safety factor of .25% off of the already derated cable. Can you please provide a longhand calculation for your solution on this application?
I am having dual speed motor of cromton greaves make of 3.7 KW -1400 rpm and 5 KW - 900 rpm. Please let me know groups and winding connction for rewinding purpose.
please send me the previous year's question papers of jindal GET exams
define the active power?
how can calculation ate Amps for cabel. Ex-for 1sqmm wire hou many amps we can draw
We are designer please help me calculate the size of 11kv cables from step up transformer to M.V panel, total load is 5 mega watt distance 900 feet (used aluminum type cables) please provided formula for calculate the cable with example.
What is primary and backup protection?
if negative of DC supply used and positive is grounded through EGB, and if ELCB used in the system then is it sense the positive volatge and get tripped is it possible?
How to measure the Harmonic Distortion of UPS ie THD?
Why choke coil is connected in series with starter in tubelight??why starter is connected in parallel to tubelight??
What are the main advantages of bode plot?
please write motor, transformer, Generator setting, fault level calculation of Tr.etc
If UG power cable both ends are to be earthed or what? If not why?
