Question { Alstom, 77979 }

what is droop?

Answer

The rate of change of the output voltage when the control
signal is in the hold state.
The droop rate is due to leakage currents flowing on or off
the hold capacitor and therefore the droop rate is less for
large capacitors.

dVH/dt = Ileakage/CH

VH: Hold voltage
t: time
I: current
C: capacitor

Question { 20560 }

whats the one main difference between UPS & inverter ?
And electrical engineering & electronics engineering ?

Answer

uninterrupt power supply is mainly use for short time .
means according to ups VA it gives backup.
ups is also two types : on line and offline . online ups
having high volt and amp for long time backup with with
high dc voltage.but ups start with 12v dc with 7 amp.
but inverter is startwith 12v,24,dc to 36v dc and 120amp to
180amp battery with long time backup.

Question { 20560 }

whats the one main difference between UPS & inverter ?
And electrical engineering & electronics engineering ?

Answer

) CHANGE OVER TIME: An off-line ups (the standard) switches
to the batteries in 3 to 8 milliseconds, after the main
power has been lost.
The typical Inverter changes over in about 500 milliseconds

2) SIZE: Off-line UPS's go up to about 2kVA
Inverters go to 16kVA, 3 phase(what i could find browsing)

3)VOLTAGE REGULATION: UPS's have automatic voltage
regulation (AVR) set on average at 220v
Inverters output voltage is the same as the mains input
voltage (South Africa = 230V)



An inverter can transform a voltage from say 12volts dc and
up to 230v AC.

UPS means Uninteruptable Power Supply. If you use an UPS
between your computer, and your socket in the wall, and
experience a power failure, the UPS will act as a battery
and give you some extra minutes work time to save your
work, and turn of the machine properly. Without the UPS
your machine would die immediately


Electrical engineering, sometimes referred to as electrical
and electronic engineering, is a field of engineering that
deals with the study and application of electricity,
electronics and electromagnetism. The field first became an
identifiable occupation in the late nineteenth century
after commercialization of the electric telegraph and
electrical power supply. It now covers a range of subtopics
including power, electronics, control systems, signal
processing and telecommunications.

Electrical engineering may or may not include electronic
engineering. Where a distinction is made, usually outside
of the United States, electrical engineering is considered
to deal with the problems associated with large-scale
electrical systems such as power transmission and motor
control, whereas electronic engineering deals with the
study of small-scale electronic systems including computers
and integrated circuits.Alternatively, electrical engineers
are usually concerned with using electricity to transmit
energy, while electronic engineers are concerned with using
electricity to transmit information.

Question { NTPC, 12353 }

diff between grounding & earthing

Answer

electrical supply system is often connected to earth
ground, ground and neutral are closely related. Under
certain conditions, a conductor used to connect to a system
neutral is also used for grounding (earthing) of equipment
and structures. Current carried on a grounding conductor
can result in objectionable or dangerous voltages appearing
on equipment enclosures, so the installation of grounding
conductors and neutral conductors is carefully defined in
electrical regulations. Where a neutral conductor is used
also to connect equipment enclosures to earth, care must be
taken that the neutral conductor never rises to a high
voltage with respect to local ground