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kurt jorgensen
{ City } ipswich
< Country > australia
* Profession * applicaton engineer
User No # 101223
Total Answers Posted # 96
Total Answers Posted for My Questions # 0
Total Views for My Questions # 0
Users Marked my Answers as Correct # 358
Users Marked my Answers as Wrong # 99
Question { 13289 }
conditions for parallel operation of dc generators
Answer
- Number of phases
- Voltage
- Frequency
- Phase angle
- Wave form
They will also have to have a way of controlling the load
sharing between the sets both active and reactive.
| Is This Answer Correct ? | 15 Yes | 13 No |
Question { 5373 }
Can we use droop CT in neutral in place of W phase of
alternator ?
Answer
series star connected alternator it can be placed in the
output end, centre tap or neutral (star point end of the W
phase winding).
Remember it must be inserted as per the instructions as to
how many parallel coils pass through it and P1 must always
be in the correct direction. Always have P1 towards the
star point.
I have done this a number of times where the room around
the windings do not allow fitting elsewhere.
| Is This Answer Correct ? | 0 Yes | 0 No |
why voltage between neutral and earth, with out secondary
grounded distribution transformer
Answer
direct path between these and therefore should not have a
voltage. But this is in a perfect world.
In reality the insulation in the transformer is not
perfect. It will have weak spots in it. When you connect a
meter between the earth and the neutral you are measuring
the voltage between the neutral and the weakest spot in the
insulation. You will find that if the insulation is good
there will be very little or no current flow if an ammeter
is connected between the earth and the neutral.
I have experienced this and have investigated to determine
why it is happening.
| Is This Answer Correct ? | 2 Yes | 0 No |
Question { 3453 }
Why Lead-Acid cell voltage is 2.1 volt, why we can not
chenged it cell voltage by using extra row-material, only
incries its AH.
Answer
can not produce a higher voltage. By putting more rows of
plates it does not change the reaction to increase the
voltage only the amount of current that can pass through
the cell.
| Is This Answer Correct ? | 0 Yes | 0 No |
Question { 3096 }
i want to trigger ATS (Mains +Generator )from external
system could any body help me in this regard ??
is it posible if yes please tell me how?
Answer
load over it is possible.
Some ATS have a function where an external input can
trigger the change over.
If it does not a remotely controlled relay can switch one
of the phase to the under voltage sensing. The ATS will
then think the mains have been lost.
| Is This Answer Correct ? | 0 Yes | 0 No |
why we use 50hz frequency in india why not other frequencies
like 52,59,42 etc
Answer
machines is set by the frequency. To generate 50 Hz the
generator must run at 3000, 1500, 1000, rpm depending on
the number of poles (2, 4 and 6). At 52 hz it would be
3120, 1560, 1040 rpm.
| Is This Answer Correct ? | 3 Yes | 0 No |
Question { 5419 }
I have running 4 generator in paralel.All generators
Voltages is same(470 V),KW also same (100 KW) but only No2
generator Amper is high than another generators.
DG No:1,3,4 470V,100KW, 150 A
DG No:2 470V,100KW,400 A
Answer
voltage) it will take more kvar. This will only be shown by
a current not load. The KW will remain the same.
Reduce the excitation (voltage setting on the AVR) on No 2
generator until it is reading the same current as the other
3 generators.
| Is This Answer Correct ? | 1 Yes | 1 No |
230v 1 phase Phase and Neutral insert in Bulk water what happens.
Answer
enough it will cause an overload. If they are far enough
apart they will heat the water and can make the water boil
between the wires.
This method has been used to load test DG's. 3 pointed
metal plates are fixed onto a triangle of wood and a phase
connected to each. When the plates are lowered into the
water current will flow through the water. The further the
plates are lowered the greater the current.
Note that this is very dangerous if great care is not taken
and all people are kept away from the water.
| Is This Answer Correct ? | 2 Yes | 0 No |
Question { 3730 }
in magnetic field we send current to generate flux,why not
voltage?
Answer
produce an electrical field
| Is This Answer Correct ? | 3 Yes | 0 No |
Question { 4461 }
Why dnt we generate 5-ph or 7-ph supply like as 3-ph supply
Answer
produce a rotating magnetic filed. This allows 3 phase
induction motors to start without special methods as with
single phase.
Extra phases have been used at times but it increases the
costs of all the power lines.
Where 3 phase can be 3 or 4 wire, 5 phase would be 5 or 6
wire and 7 phase would be 7 or 8 wire.
| Is This Answer Correct ? | 1 Yes | 0 No |
DEAR ALL
I have motors ( 10 units )each one is 90kw 380V 50 HZ 1000rpm
but new local pwer is 220v 60 hz
requierd rpm should be 1000
pleas what the beast solution is used frequncy converter or
rewinding all motos or chang all motors
thanks
Answer
is wrong.
The second issue is the speed - 1000 rpm uses a 6 pole
motor at 50Hz. 6 pole at 60Hz is 1200 rpm and 8 pole is 900
rpm.
You will need to change the voltage and frequency.
If the motors are belt drive changing the ratio of the
pulleys will fix the problem of speed.
| Is This Answer Correct ? | 0 Yes | 0 No |
Question { 3254 }
In a 3 phase system a neutral exists so that any unbalanced
currents can flow through it towards earth.... but a phase
demands a particular current as per the load attached to
it....then where does the extra current come from the goes
in the neutral??....I mean in an unbalanced system a phase
demands a current as per its load attached....then where
does the unbalanced current come from??
Answer
transformer is in star to have a neutral. The current
flowing in the neutral does not flow to earth but to the
star point. The star point is the opposite end of the
windings where the phase is connected and the 3 are joined
together. The current in a balanced 3 phase system for
example a 3 phase motor flows through the phase wires and
not the neutral. An unbalance would be where something is
connected to a single phase and the neutral. This would be
lights for example. Here the current flows from the phase
and back through the neutral.
| Is This Answer Correct ? | 1 Yes | 0 No |
Question { 53486 }
What is difference between ON delay and OFF Delay Timer?
Answer
delay before the output is turned on.
OFF delay timer - after the input is turned off there is a
delay before the output is turned off.
| Is This Answer Correct ? | 64 Yes | 21 No |
Question { 12978 }
Why the voltage n frequency of the incoming generator is kept slightly higher than d grid voltage n frequency while synchronization ?
Answer
In practice the incoming generator voltage and frequency
should be slightly hogher than the grid.
This is to prevent the set from tripping on reverse power
or kva. The incoming generator will pick up some load
straight away so the frequncy and voltage matches the grid.
| Is This Answer Correct ? | 0 Yes | 1 No |
