ABCD Per a Meters of Transmit Ion Line

B.M.A.S. Engineering College, Agra-007

LABORATORY MANUAL

POWER SYSTEM LAB(EEE-751)

B.TECH 4TH – YEAR (7th SEM)

DEPARTMENT

OF

ELECTRICAL AND ELECTRONICS ENGINEERING

I N D E X

S.No Name of the Experiment Date of perform

Prepared by Omprakash



EXPERIMENT NO.

Object:- To find out A,B,C,D, parameters, Hybrid parameter and image parameters of a given transmission line

Instrument Used:-Transmission line model is consisting of four sections of transmission on line operatable at 220V with current rating at 2A connected in π network. A continuous variable power supply with two digital voltmeter and two digital ammeters mounted on front panel fitted in ms sheet box complete with patch chords for interconnections.Note: Transmission line model consists of four sections and each section represents 50 km long 400KV transmission line. Parameters of 50km ling 400KV Transmission line are taken as :-

Series inductance = 80mHSeries Resistance = 2ΩShunt capacitance = 0.47μFLeakage resistance (shunt conductance) = 470kmho

For actual 400KV transmission line range of parameter is-

l = Series inductance = 1.0 to 2.0mH/kmr = Series Resistance = 0.5 to 1.5Ω/kmc = Shunt capacitance = 0.008 to 0.01047μF/kmg = Leakage resistance (shunt conductance) = 3×10-8 to 5×10-8mho/km

THEORY- ABCD parameters are widely used in analysis of power transmission engineering where they will be truned as “generalized circuit parameters” ABCD parameters are also called as “Transmission parameter”. It is conventional to designate the input port as sending end and the output port as receiving end while representing ABCD parameters.

ABCD parameters equations are given as:-

=



Transmission line model

~

VS

IS

A BC D

VR

IR


Assuming the receiving end open circuited.i.e.I2 = 0.VS

A = --------------- Reverse Voltage ratio and is unitlessVR

IS

C = --------------- Transfer admittance. unit is mho.VR

VS

B = --------------- Transfer impedance and expressed in ohmIR

IS

D = --------------- Reverse current ratio and is unitlessIR

In hybrid parameter representation both short circuit and open circuit terminal conditions are utilized hence this parameter representation

Is known as hybrid parameter representation. Here:-

=

If receiving end is short circuited, i.e. VR = 0

VS

h11 = --------------- Input impedance and unit is ohms.IS

VS

h21 = --------------- Forward current gain and is a unitless quantity.IS

In a similar way for the sending end open circuited i.e. Is = 0

VS

h12 = --------------- Reverse Voltage gain and has no unitVR

IR

h22 = --------------- Output admittance and is expressed in mho.VR

In a transmission line if the impedance at the sending end with Z12 at receiving end Z11be and simultaneously the impedance looking back from receiving end with Z11 at input port is Z12

then Z11 and Z12 are termed ads the Image impedance of the network.



VS

-IR

IR

VR

h11 h12

h21 h22

C D


We can conveniently express the image impedance in terms of ABCD constant as :-

ABZ11 = √ -----------

CD

And BD

Z12= √ -----------AC

However image impedance so not completely define a network. We need another parameter which we shall get from the voltage end current ration known as image transfer constant and can be calculated as:-

1 BCσ = ---- in == tan h-1√ ------------

2 AD

Calculation and observations

For ABCD parametersIS (IR =

0)

S.NO VS IS VR A = V1/ V2 C= I1/ V2

IS (IR)




~

Vs Is

VR I R


S.NO VS IS IR B = V1/ I2 D= I1/ I2

For Hybrid parameters:-IS (IR)

S.NO VS IS IR h11 = V1/ I1 h21= I2/ I1

IS (IR)

S.NO VR IR VS h12 = V1/ V2 h22= I2/ V2




~


~


~


Image parameters

ABZ11 = √ -----------

CD

BDZ12= √ -----------

ACBC

tan h-1√ ------------AD

Precautions:1. All connection should be tight.2. Keep care always from the practical panel board.





EXPERIMENT NO.

Object:- To study i) Constriction of the differential relay. ii) Operational characteristic of the relay. iii) Calculate % bias and determine the minimum operating current.

Instrument Used:-

S.NO. Item Type Specifications Quantity 1. Ammeter MI (0-10) A 02 2. Voltmeter MI (0-300) Volt. 01 3. Autotransformer 1-Φ (0-260) Volt,10A 01 4. . Connecting

Wires PVC Coated 1/18 SWG L.S.

5. Neon Lamp 1A capacity 01 6. Isolation

Transformer -- 01

7. Rheostat 10A,20Ω 01 8. Rheostat 5A,45Ω 01

Theory: A Differential relay is “one that operates when the vector difference of two or more similar electrical quantity exceeds a predetermined amount”. Most differential relay applications are of the current differential type. The element protected by relay might be length of circuit a generator winding of Biased differential protection of two winding transformers against internal phase and earth faults etc. the second of C.T.S. are interconnected and coil of and over current relay is connected across the ct secondary circuit. Then differential relay current will be proportional to the vector difference between the current entering and leaving the protected circuit. The differential current required to operate percentage differential relay is a variable quantity owing to the effect of the restraining coil. The differential current in the operating coil is proportional to I1 –I2 and the equivalent current in restraining coil is proportional to (I1 + I2) / 2 since the operating coil is connected to the mid point of R.C. Working of control panel:

1. By removing the top lid cover of relay, adjust the bias top on both sides i.e. either at 20%, 30% or 40% for each setting, tripping time etc and as well as minimum current operate setting.

2. Adjust relay operating time which can be adjusted by movement of the disc backstop, which is controlled by rotating a knurled moulded disc at the base of the graduate time multiplier scale. At present, we have kept T.M.S. at 1 (one).

3. Adjust relay minimum operating current of the relay, which is determined by the tension of the disc control spring and can be adjusted by rotating a Prepared by Omprakash







EXPERIMENT NO.

Object:- To determine the fault in a cable using cable fault locator.

Instrument Used:-Cable fault locator complete kit THEORY- Faults occurring in cables, which are in use on lower distribution voltages, are considered. The common faults are occur in cables. 1. Ground fault- The insulation of the cable may break down causing a flow of current from the core of the cable to the lead sheath or the earth. 2. Short circuit fault- If the insulation between two conductors is fault, a current flow between them. Methods used for localization ground and short circuit faults. In the case of multi core cables it is advisable, first of all to measure insulation resistance each core to earth and also between cores. Loop test are used for localization of ground and short circuit fault. These tests can only be used if a sound cable runs along with faulty cable or cables. The loop tests work on the principle of a Wheatstone bridge. The advantages of these tests that their set up is such that the resistance of fault is connected on the battery circuit and therefore does effect the result however if the fault resistance is high, the sensitivity is adversely affected. MURRAY LOOP TEST- The connection of this tests are shown in the figure . In both cases the loop circuit formed by the cable conductor is essentially a Wheatstone bridge consisting of resistances P,Q,R and X.G is the galvanometer for indication of balance. Under balance condition: X/R=Q/P Or X/R+X=Q/P+Q X=Q(R+X)/P+Q Where(R+X) is total loop resistance formed by the sound cable and the faulty cable. When the conductors have the same cross sectional area and the same receptivity, the resistances are proportional to lengths. If I1 represents the lengths of the fault from the test end and l the length of each cable. I1= Q(2l)/P + Q The above relation shows that the position of the faulty may be located when the length of the cable is known, also the fault resistance does not alter the balance condition because its resistance inters the battery circuit hence affects only the sensitivity of the bridge circuit. However ,if the magnitude of the fault resistance is high, difficulty may be experienced in obtaining the balance on account of decrease in sensitivity and hence accurate determination of the position of the fault may not be possible. In such a case, the resistance of the fault may be reduced by applying a high direct or alternating voltage-in consistence with the insulation rating of the cable- on the line so as to carbonize the insulation at the point of the fault. CIRCUIT DIAGRAMS-







%Impedance = 15/230 ×100 = 3.75%For T/F-2Full load current = 150 / 138 = 6.28 AFull load short circuit voltage at 6.57 A = 11 V %Impedance = 11/226 ×100 = 4.86 %

%Impedance of transformer on 100 MVA base% Impedance on 100 MVA base = %Z × 100/MVAFor T/F-1 : % Impedance on 100 MVA base = 3.75 × 100/0.003 = 125000%For T/F-2 : % Impedance on 100 MVA base = 4.86 × 100/0.0015 = 324000%

Line Impedance on 100MVA baseLine Impedance on 100MVA base = Line Impedance on 100 ×100/(KV)2

Line Impedance = 2+ 2= 4Line Impedance on 100MVA base = 4× 100 ×100/(0..226)2 =391573.34

Sample I As a sample we are considering the given design and fault at point f. considering 0

line impedance

Fault impedance = 125000 + 324000 = 449000

Formula Fault MVA = 100 × 100/ Fault impedance on 100 MVA base Fault MVA = 100 × 100 /449000 = 0.0222717

Fault current at transformer II outputFormula I3 = Fault MVA × 1000/ √3 ×Volt in KV

I3 = 0.0222717 × 1000/1.723 × 0.138 = 93.18 AFault current at transformer I output

I2 = 0.0222717 × 1000/ 1.723 × 0.4 = 32.14 A Fault current at transformer I input

Apply the voltage 40V at port 400V side of transformer I

Measured current values at 40V

These current value at 400V shell be

Theoretical values

I3 = 1.19A I3 = 1.19 ×10A I3 = 11.9AI2 = 2.08A I2 = 2.08A ×10A I2 = 20.8A I1 = 3.65A I1 = 3.65A × 10A I1 = 36.5AHence the practical values and theoretical values ate nearly same and little difference due to lead impedance onlyCircuit diagram:



125000 324000


Sample II As a sample we are considering the given design and fault at point f. considering 4

line impedance

Fault impedance = 125000 + 391573.32 + 324000 = 1232146.00Formula Fault MVA = 100 × 100/ Fault impedance on 100 MVA base Fault MVA = 100 × 100 /1232146.00= 0.0081159Fault current at transformer II outputFormula I3 = Fault MVA × 1000/√3Volt in KV

I3 = 0.0081159× 1000/ √3 ×0.138 = 1.18 AFault current at transformer I output

I2 = 0.0081159× 1000/ √3 ×0.226= 2.08 AFault current at transformer I input

I2 = = 0.0081159× 1000/ √3 ×0.4= 3.65 AApply the voltage 40V at port 400V side of transformer I

Measured current values at 23V

These current value at 230V shell be

Theoretical values

I3 = 1.18 A I3 = 1.18 A × 10 = 11.8A I3 = 11.8AI2 = 2.08 A I2 = 2.08 A × 10 = 20.8 A I2 = 20.6A I1 = 3.65 A I1 = 3.65 A × 10 = 36.5A I1 = 36AHence the practical values and theoretical values ate nearly same and verified

Precautions: 1. The voltage at 400V side of transformer I should not exceed 450V at any time. 2. The voltage at 238V side of transformer I should not exceed 250V at any time.3. All connection should be tight.4. Keep away from the practical panel board.



125000 391573.32 324000








S.NO. V I W

CALCULATION:-

RESULT:-

PRECAUTIONS:- 1. All connection should be tight.2. Apparatus should be of proper range.3. Do not touch live terminals.4. Reading should be taken carefully.5. Applied voltage should be small (reduced) voltage.6. Machine should be at rated speed.




EXPERIMENT NO.

Object : - To measure the sub transient direct axis(Xd”) and sub transient quadrature axis (Xq”) reactance of an alternator.

Instrument Used :-

S.NO. Item Type Specifications Quantity01. Ammeter MI (0-5/10) A 0102. Ammeter MC (0-1/2) A 0103. Voltmeter MI (0-75/150/300) Volt. 0104. Synchronous

machine1.5KW,1500RPM 01

05. Auto transformer Single-phase 0-260V,10A 0105. Connecting

WiresPVC Coated 1/18 SWG L.S.

Theory : - Any two phases of a three phase machine are connected in series and a single phase voltage is impressed across the rotor is stand still. The impressed voltage is adjusted to pass sufficient current in the two series connected armature winding. Now the rotor position is adjusted with hand to get maximum deflection of the ammeter placed in the field winding circuit. Under this condition d-axis sub transient Zd” is given by-

VZd” = ----------

2ImaxHere V and Imax are the voltmeter and ammeter readings respectively. If thr wattmeter records P watt then-

PCosØ = --------------

VImaxOr SinØ = √ 1 – (P/VImax)2

D- axis sub transient reactanceXd” = Zd” SineØ

VZd” = ---------- × SinØ = √ 1 – (P/VImax)2

2Imax




If the rotor shaft is rotated by hand through half pale pitch ,then peak of the resultant armature mmf coincides the q-axis. These conditions ate those for which Xq” has been defined . Under these conditions the instruments readings give.

Xq” = Zq” SineØ

CIRCUIT DIAGRAM :-

OBSERVATIONS TABLE:-S.NO. V I W

CALCULATION:-

RESULT:-

PRECAUTIONS:- 1. All connection should be tight.




2. Apparatus should be of proper range.3. Do not touch live terminals.4. Reading should be taken carefully.5. Applied voltage should be small (reduced) voltage gradually.

EXPERIMENT NO.

Object : - To test the breakdown voltage of the transformer oil.

Instrument Used:-Transformer oil testing Instrument or kit

THEORY- When a sample of oil is subjected to dialectic stress in a gap between two spheres the materials of higher conductivity and higher spheres capacity are drawn into the intense field between the spheres and causes a distortion of the fields resulting in local high density and disruption begins at these points.

When testing transformer oil it is found often that one of more discharge occur across the gap at comparatively low voltage due to the presence of water particles but that the voltage can be raised to a vary much higher value before complete rupture occurs.

If particles of higher dielectric constant than the oil are drawn into the intense field, they will cause excessive local stress which may result in dissociation of ionization of oil and the gases of ionization may bridge the gap and causes complete rupture.

In standard specifications for ‘Insulating Oil’ the method of Appling the testing voltage (which must be alternator of approximately sine waveform of frequency between 25 and100 Hz and with a peak factor of √2 ±5 % ) has been laid sown. The test has to be carried out under standard conditions. The minimum dimensions of the test cell, diameter of the electrode and the distance between them specified.

Voltage should be increased gradually under continues observation of the measuring until the breakdown occurs. To set oils of high quality the distance between electrodes should be adjusted to 2 mm. The equipment permit 310 KV /cm to be measured. For testing oils of medium quality or inferior quality the spark gap should be adjusted to 4mm by means of a distance gauges. The insulating material oil testing cup is equipped normally with two calotte-shaped electrodes of 36 mm dia, radius of each sphere is 25mm.

CIRCUIT DIAGRAMS-




OBSERVATIONS-

CALCULATION-

RESULT- Distance between electrodes = 2 mm , Breakdown Voltage = 42 KVOr 4 mm, Breakdown Voltage = 42 KV

PRECAUTIONS-1. Supply voltage should be constant.2. All connection should be tight and right.3. Connecting leads should have tight connection.4. Earthing of pot should be compulsory




EXPERIMENT NO.

Object :- To determine and measure the ZERO sequence reactance (X0) of synchronous machine.

Instrument Used : -

S.NO. Item Type Specifications Quantity01. Ammeter MI (0-5/10) A 0102. Ammeter MC (0-1/2) A 0103. Voltmeter MI (0-75/150/300) Volt. 0104. Synchronous

machine1.5KW,1500RPM 01

05. Auto transformer Single-phase 0-260V,10A 0105. Connecting

WiresPVC Coated 1/18 SWG L.S.

Theory : - The zero sequence impedance of a machine is impedance offered to the flow of negative sequence current. It is defined as the ratio of fundamental component of reactive armature voltage to the fundamental component of zero sequence armature current at rated frequency.Zero sequence reactance can be measured either by connecting all the three phase of stator winding of synchronous machine in series of in parallels.i) Series connection of all the three phases is possible, only when both the terminals of each phase are accessible. For measuring zero sequence reactance, reduced single phase voltage is applied across the stator winding with three phases connected in series with the




field winding short circuited; the synchronous machine if desired may be run as an alternator at rated speed, However, The magnitude of zero sequence reactance is not much affected by the rotation of the machine. As such, test may be performed with the synchronous machine stationary. Zero sequence reactance can then be found out by recording the current, applied voltage and input power and proceeding as per the following-

Zero sequence impedance, Zo = E/3I

Zero sequence reactance, Xo = Zo [1 – (P/EI) 2]1/2

ii) Parallel circuit Zero sequence impedance, Zo = 3 E/I

Zero sequence reactance, Xo = Zo [1 – (P/EI) 2]1/2

CIRCUIT DIAGRAM:-

OBSERVATIONS TABLE:-S.NO. V I W

CALCULATION:-




RESULT:-

PRECAUTIONS:- 1. All connection should be tight.2. Apparatus should be of proper range.3. Do not touch live terminals.4. Reading should be taken carefully.5. Applied voltage should be small (reduced) voltage gradually.6. Machine should be at rated speed.

EXPERIMENT NO.

Object:- To study of IDMT Over current relay

Instrument Used :-

S.NO. Item Type Specifications Quantity1. Ammeter MI (0-10) A 012. Voltmeter MI (0-300) Volt. 013. Autotransformer 1-Φ (0-260) Volt 014. . Connecting Wires PVC Coated 1/18 SWG L.S.5. Lamp load 10A capacity 016. IDMT relay CDG -- 01

Theory : - Inverse definite minimum. time over current relay this type gives an inverse time current characteristic at values of fault current and definite time characteristic at higher values of fault current. Generally an inverse time characteristic is obtained if the value of plug setting multiply is blow 10 for values for plug setting multiplier between 10-20 the characteristic 10 to become a straight line that is towards the definite characteristic. It is widely used for the protection of distribution lines such relays have a provision for current and time settings.




IDMT over current relay has been used extensively for protection of generators, transformers and distribution network.

T (Required time of operation)The time multiplier setting (TSM) = -------------------------------------

Tm (Obtain time from relay characteristics curve

Primary current fault currentPSM = ------------------------------, OR -------------------------

Primary setting current Plug setting

CIRCUIT DIAGRAM :-

OBSERVATIONS TABLE :- TSM = 1.00,PS =1.0ACurrent (A) Time (measured) Time (Std.) PSM

TSM = 0.5,PS =1.0ACurrent (A) Time (measured) Time (Std.) PSM






CALCULATION:-

RESULT:-

PRECAUTIONS:- 7. All connection should be tight.8. Apparatus should be of proper range.9. Do not touch live terminals.10. Reading should be taken carefully.

EXPERIMENT NO.

Object : - To determine the Xd & Xq of a 3-Φ salient pole synchronous machine using slip test and the power angle curve.

Instrument Used :-

S.NO. Item Type Specifications Quantity01. Ammeter MI (0-5) A 0102. Ammeter MI (0-10) A 0103. Voltmeter MI (0-600) Volt. 0104. Rheostat Wire Wound (0-1000) Ω, (0-300) Ω 0305. Tachometer Digital (0-9999) rpm 0106. Autotransformer 3-Φ (0-400/415) Volt 0107. Connecting Wires PVC Coated 1/18 SWG L.S.




Theory : - Direct-axis synchronous reactance and quadrature-axis synchronous reactance are the steady state reactances of the synchronous machine. These reactance can be measured by performing open-circuit & short-circuit tests and the slip test on a synchronous machine.

Direct-axis synchronous reactance (Xd):- the direct-axis synchronous reactance of synchronous machine in per unit is equal to the ratio of field current. Ifsc at rated armature current from the short-circuit test to the field current, Ifo at rated voltage on the air gap line.

Direct-axis synchronous reactance,Xd=Ifsc/Ifo per unit

Thus the direct-axis synchronous reactance can be found out by performing the open-circuit & short-circuit tests on an alternator. Hence

Xd=

Quadrature-axis synchronous reactance (Xq) By Slip test : -For the slip test, the alternator should be driven at a speed slightly less then synchronous speed with its field circuit is open, 3-Φ balance reduced voltage of rated frequency is applied to armature(stator) terminals of the synchronous machine. Applied voltage is to be adjusted so that the current drawn by the stator winding is full load rated current under these conditions of operation, the variation of the current drawn by the stator winding, and the voltage across the field winding will be shown in fig. The wave shape of stator current and stator voltage clearly indicate that these are changing between minimum and maximum values. When the crest of the stator mmf wave coincides with the direct axis of the rotating field, the induced emf in open field is zero, the voltage across the terminals will be maximum and the current drawn by the stator winding is minimum as shown in fig.

Thus approximate value of direct-axis synchronous reactance, Xd=Emax/IminΩ

When the crest of mmf wave coincides with the quadrature axis of the rotating field, the included emf in the open-circuit, the field is maximum, the voltage across the stator terminals will be minimum and the circuit drawn by the stator winding is maximum as shown in fig.

Hence, approximate value of the quadrature-axis synchronous reactance, Xq is given by

Xq=Emin/Imax

It may be noted that Xd is greater then the Xq for a synchronous machine. soXq=Xqs*Xd/Xds

=(Emin/Imax)*(Imin/Emax)*Xd

CIRCUIT DIAGRAM :-

OBSERVATIONS TABLE :-

S.No. OPEN-CIRCUIT TESTIfo Vo

SHORT-CIRCUIT TESTIfsc Isc

SLIP TESTImin Imax Vmin Vmax




01.

02.

03.

04.

05.

06.

CALCULATION:-

RESULT:-

PRECAUTIONS:- 1. All connection should be tight.2. Apparatus should be of proper range.3. Do not touch live terminals.4. Reading should be taken carefully.5. Field winding of synchronous machine should be open.6. Applied voltage should be small (reduced) voltage.7. Machine should not be at rated speed.



Documents

ABCD Per a Meters of Transmit Ion Line