No. 8 problem A shunt generator has the following open-circuit characteristic at 800 r.p.m. Field amperes : 0.5 1.0 1.5 2.0 2.5 3.0 3.5 E.M.F. Volt : 54 107 152 185 210 230 245 Armature and shunt field resistances are respectively 0.1 Ω and 80 Ω. The terminal p.d. falls to 175 V when the armature current is 100 A. Find the O.C. volts and the volts lost due to (i) reduction in the field current (ii) armature resistance (iii) armature reaction.
Load flow analysis
Load flow analysis is a study or numerical calculation of the power flow of power in steady-state conditions in any electrical system. It is used to determine the flow of power (real and reactive), voltage, or current in a system under any load conditions.
Nodal Matrix
The nodal matrix or simply known as admittance matrix, generally in engineering term it is called Y Matrix or Y bus, since it involve matrices so it is also referred as a n into n order matrix that represents a power system with n number of buses. It shows the buses' nodal admittance in a power system. The Y matrix is rather sparse in actual systems with thousands of buses. In the power system the transmission cables connect each bus to only a few other buses. Also the important data that one needs for have a power flow study is the Y Matrix.
Types of Buses
A bus is a type of system of communication that transfers data between the components inside a computer or between two or more computers. With multiple hardware connections, the earlier buses were parallel electrical wires but the term "bus" is now used for any type of physical arrangement which provides the same type of logical functions similar to the parallel electrical bus. Both parallel and bit connections are used by modern buses. They can be wired either electrical parallel or daisy chain topology or are connected by hubs which are switched same as in the case of Universal Serial Bus or USB.
No. 8 problem
A shunt generator has the following open-circuit characteristic at 800 r.p.m.
Field amperes : 0.5 1.0 1.5 2.0 2.5 3.0 3.5
E.M.F. Volt : 54 107 152 185 210 230 245
Armature and shunt field resistances are respectively 0.1 Ω and 80 Ω. The terminal p.d. falls to 175 V when the armature current is 100 A. Find the O.C. volts and the volts lost due to
(i) reduction in the field current
(ii) armature resistance
(iii) armature reaction.
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P 28.1.
Characteristics of
8. A shunt generator has the following open-circuit characteristic at 800 r.p.m.
D.C. Generators
Field amperes
E.M.F. Volt
0.5
1.0
1.5
2.0
2.5
3.0
3.5
ET 28.2.
54
107
152
185
210
230
245
Armature and shunt field resistances are respectively 0.1 2 and 80 2. The terminal p.d. falls to 175 V
when the armature current is 100 A. Find the O.C. volts and the volts lost due to (i) reduction in the field
current (ii) armature resistance (iii) armature reaction.
Separately-excited
Generator
[220 V (1) 27 V (ii) 120 V (iii) 8 V]
W Fig. 28.1
I Fig. 28.2
T Fig. 28.3
E P 28.3. No-load
The open-circuit characteristic of a shunt generator when driven at normal speed is as follows :
Field current
9.
0.5
1.0
1.5
2.0
2.5
3.0
3.5 A
O.C. volts
The resistance of armature circuit is 0.1 2. Due to armature reaction the effective field current is given
by the relation I (eff.) = I-0.003 I, Find the shunt field circuit resistance that will give a terminal voltage
of 220 V with normal speed (a) on open circuit (b) at a load current of 100 A. Also find (c) number of series
turns for level compounding at 220
1200 and (d) No. of series tuns for over-compounding giving a terminal voltage of 220 V at no-load and
230 V with 100 A armature current.
54
107
152
185
210
230
240 V
Curve for
Self-excited
with 100 A armature current ; take number of shunt turns per pole as
Generator
f Fig. 28.4
W Fig. 28.5
W Fig. 28.6
[(a) 80 2 (b) 66 Q (c) 6.8 Q (d) 9.1 turns]
10. Find how many series turns per pole are needed on a 500-kW compound generator required to give
450 V on no-load and 500 V on full-load, the requisite number of ampere-turns per pole being 9,000 and
6,500 respectively. The shunt winding is designed to give 450 V at no-load when its temperature is 20°C. The
final temperature is 60°C. Take a,= 1/234.5 per °C.
W 28.4 How to Find
Critical Resistance
[ 2.76] (Electrical Technology, Allahabad Univ. 1977)
Rc ?
OBJECTIVE TESTS – 28
EP 28.5 How to Draw
O.C. at Different v
1. The external characteristic of a shunt generator
(a) shunt
(6) series
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2/22/2021
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