Description : Christopher Lee - MMF n°14 (06.1966)
Descrição: Christopher Lee - MMF n°14 (06.1966)
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an ever increasing list of chemical terms
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Poetry maggie and milly and molly and may ee cummings analysis form & technique
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Through an email conversation between Allen, Forst and Haugaard, this article explores the relationship between the dyads power and reason, justice and domination. In much of the literature reason ...
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Expectations of class and gender within the fixed social structure of the Regency Period.
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ABB Synchronizing and paralleling devices and systems
Circuit diagram for regulation of an alternator by EMF and MMF methods
Fuse rating = 125% of rated current = =
Name plate details of induction motor Rated Rated Rated Rated
power current voltage speed
= = = =
REGULATION OF AN ALTERNATOR BY EMF AND MMF METHODS EXP. NO: DATE: AIM: To determine the voltage regulation of 3-phase alternator by using EMF and MMF method.
FORMULAE: EMF Method: 1. Armature resistance, Rac = 1.6 × R dc Ω 2. Synchronous impedance, Zs = (for same If value) Ω
3. Synchronous reactance, Xs =
√ Ω
4. Eph = √ (Vph cosФ + Iasc Rac) 2 + (Vph sinФ + Iasc Xs) 2 (Volt) Where, (+) for lagging power factor (-) for leading power factor 5. % Regulation =
x 100
Tabulation: Open circuit test
SL. NO
Open circuit line voltage, VL (V)
Field current, I f
Open circuit phase voltage, Vph(V)
1 2 3 4 5 6
Short circuit test
SL. NO 1
Short circuit current, I sc (A)
Field current, I f (A)
MMF Method: 1. Vph =
(Volts)
2. IL = Iph =
(Volts)
3. Calculating open circuit voltage = V ph + Iph Ra cosФ (Volts) 4. Field current corresponding to short circuit current = F AR (Amps) 5. FR = √ (Fo ± F AR sinФ + Iasc Xs) 2 + (F AR sinФ) 2 Where (+) for lagging power factor (-) for leading power factor
6. % Regulation =
x 100
PROCEDURE:
OPEN CIRCUIT TEST: 1.
Give the connections as per the circuit diagram.
2.
Keep the alternator side TPST open till the completion of OC test.
3.
The motor side DPST switch is closed and the set is started with the help of the 3-point starter.
4.
The set is run at various speeds by adjusting the field rheostat of DC motor and the corresponding voltage generated by the alternator is noted down by the voltmeter.
5.
This step is repeated up to the rated voltage generated by the alternator.
6.
By varying the alternator field rheostat, the voltage generated for different currents are noted and tabulated.
SHORT CIRCUIT TEST: 1.
Give the connections as per the circuit diagram.
2.
The alternator terminals are short circuited by closing the TPST switch.
3.
The DC supply is given to the motor by closing DPST switch and the motor starts to rotate.
4.
The field rheostat of alternator varied up to rated current and the corresponding field current of alternator noted down.
5.
Now the supply of the set is switched off by opening both DPST switches.
Tabulation: EMF Method: Eph (Volts)
cosФ
Lag
% Regulation Lead
Lag
Lead
0.2 0.4 0.6 0.8 1
MMF Method:
cosФ 0.2 0.4 0.6 0.8 1
Fo
F AR
Eph (Volts) Lag Lead
% Regulation Lag Lead
GRAPH: A) OC and SC characteristics curves are drawn as 1.
Field current Vs SC current
2.
Field current Vs OC voltage
B) The regulation curve is drawn between power factor and regulation. 1.
Power factor Vs Regulation
MODEL GRAPH:
OC and SC Characteristics curve
Regulation curve
Model calculation for EMF method
Model calculation for MMF method
RESULT: Thus the voltage regulation of an 3 phase alternator determined by EMF and MMF method.
