what is the difference between LPF and UPF wattmeter and
where it is used.
Answers were Sorted based on User's Feedback
Answer / maniveer
LOW POWER FACTOR(LPF) & HIGH POWER FACTOR(UPF)
In open circuit test the secondary winding of transformer is kept open.As the secondary side is open, the entire coil will be purely inductive in nature.So the power will be lagging due to inductive property of the circuit. So LPF(Low Power Factor) Wattmeter is used in OPEN CIRCUIT TEST of Transformer.
In short circuit test the secondary winding of transformer is short circuited. As secondary side is short circuited the entire coil will be purely resistive in nature.So the power factor will be unity. So UPF(Unit Power Factor) Wattmeter is used in SHORT CIRCUIT TEST of Transformer.
Is This Answer Correct ? | 258 Yes | 30 No |
Answer / venkata krishna
LPF wattmeter is used for measuring power in highly
inductive circuits & UPF wattmeter is used for measure power
in resistance circuit in which the power factor ranges from
0.5 to unity.
Is This Answer Correct ? | 126 Yes | 21 No |
Answer / potnur hemarao
Lpf is used in power measuring in high inductive circuit and upf is used in power measuring in resistance circuit which power factor ranges 0.5 to unity
Is This Answer Correct ? | 44 Yes | 8 No |
Answer / nitish kennedy
Low Power Factor wattmeters are specially designed to measure power at low power factor .
Ordinary wattmeters (i.e. UPF) are not accurate in measuring power at low power factor beacuse of -
low deflecting torque.
error due to inductance of of pressure coil is large at low power factor.
So some modifications are done in LPF wattmeters-
low value of pressure coil resistance to increase the torque.
pressure coil current is compensated using compensating coil.
capacitor is connected in pressure coil to reduce the error due to pressure coil inductance.
control torque is made very small.
Is This Answer Correct ? | 5 Yes | 0 No |
Answer / k.prakashchandra
LPF -low pf UPF- unity pf.In lpf meter pf compensation is
done and is accurate at the specified low pf.
Is This Answer Correct ? | 22 Yes | 33 No |
Answer / suresh
HERE LPF USED TO measure the low current & UPF is used to measure the high current. Then low pf and unity power factor
Is This Answer Correct ? | 10 Yes | 26 No |
why wire sizes are 3/29 or 7/29 and why not wire sizes are 2/29 or 6/29?
What is best method of Calculating Short Circuit current in power system network.
what is meant by vector group of a transformer? How can it be derived?
what are check points to be checked while charging switchyard?(CT,PT,BREAKER,POWER TRANSFORMER)
what is the difference in MCB, MCCB, RCCB, ELCB, & MPCB (motor protection circuit bracker)
12 Answers Afcons, Bhel, CIHSR, DCS, IOCL, L&T, Lupin, Siemens,
derive DC RMS value for half wave rectifier?
what are the usual topology of transformers at different substations in the power system and why that particular topology is choosen. what are the limitaions of that topology?
What are gain margin and phase margin?
what you mean by current? what you mean by voltage? what is difference between star and delta connection in motor side?
What is VCC?
Why we should use delta connection in primary and star connection in an distribution transformer, which converts 400v a.c. voltage to 33kv.
15 Answers ABC, Kirloskar, Sify,
why we are testing cables with DC supply not with AC supply?
9 Answers Aurobindo, DEWA, L&T,