Answer / kj

DG's are usually rated at 0.8 PF lagging. There is no
issues with running the DG at another higher or lower
lagging PF. Usually the output kw of the engine is set at
80% of the kva rating. For example a 100 kva DG will have
an engine rated at 80 kw. This will al;low for a full load
current of about 140 amps at 0.8 PF. Increasing the PF
towards unity the maximum load current must be reduced
until it is about 110 amps otherwise the engine will be
overloaded. If the PF is reduced below 0.8 PF the maximum
current must not exceed 140 amps. This means the kw of the
load must be reduced. This is to stop the windings in the
alternator being burnt.

Going to a leading PF will cause voltage instability and
can cause damage to the alternator.

Answer / k.prakashchandra

Keeping pf at 0.8 lag when running in parallel means the
terminal voltage of gen is higher than the system or busbar
voltage.But it results in higher gen & field currents which
cause unwanted heating of armature and also the field.If
you keep the pf at unity or -ve,the gen does not contribute
to system stability.The generator should also share the
reactive power of the system, which is usually
lagging.Anyway pf may be maintained at 0.9 to 0.95 lag.

Answer / meenakshi

if power factor goes beyond 0.8 (say 0.9), your dg will be
over loaded and may trip or call for frequent overhauls.

1hp= how much rpm

0 Answers  

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A commercial Building is designed with 14th floor levels with indoor substation of three phase transformer with rated capacity of 1000 Kva.The transformer delivered 65% of its rated capacity at 0.67 power factor lagging.Because of low power factor, the power customer was penalized and certain cost was charged accordingly based on every point percentage lower than 85%.This situation may repeatedly happen on the succeding energy bills of power customer.The power customer is desired to improve its historical power factor of 0.67 lagging and no further penalty be impose by the local power company on the next bill. Q: Identify the appropriate solution you want to offer to Client?.Justify SCIENTIFICALLY and MATHEMATICALLY the principles behind the solution.

0 Answers  

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Different STANDARDS (BS, IS, IEC etc) gives different informations on CT specification. How they correspons w r t each other (i.e I mean to say BS provides "knee point voltage" but IS does not, then how can i select CT)

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Why 3 phase induction motor getting supply in body if one of it's phase is cut

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I have 12MW gas engine based power plant its running parallel with grid. my problem is When cpp run in island mode(without geb) that time geb transformer power factor is 0.2 lagging. When cpp run with parallel that time power factor is 0.94 lagging So how can i maintain power factor ofgeb transformer in island mode 0.9 lagging?

1 Answers   SPCL,

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why transformer rating in KVA ?

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To check the earth condition (In plug points); the voltage between earth and Neutral is in below 5 volts. Is it correct

6 Answers  

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In my power station 220 volts dc battery set. they coneected 84th cell taped

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6. A DC AMMETER HAS R=0.1 OHM & CURRENT RANGE IS 0-100 A IF THE RANGE IS TO BE EXTENDED TO 0-500 A THEN METER REQUIRES SHUNT RESISTANCE OF ..........

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how much Amp we can put in 1200kva generator?

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why current transformer secondary is short circuited an what will happen if connect very high resistance acrossthe secondary side of current transformer?

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Why 11KV/440V distribution supply use for Domestic use?

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